Dr Caroline Leaf – Where Angels Fear To Tread

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After a day-trip to Movie World, and then a slight distraction by Eurovision, I had a quick look at Facebook before going about my evening chores. Upon reading Dr Leaf’s latest social media meme, I was aghast!

Dr Caroline Leaf is a communication pathologist and self-titled cognitive neuroscientist. Hiding in amongst her “Scientific Philosophy” was this juicy factoid: “Researchers found that intentional thought for 30 seconds affected laser light.” This is, apparently, also proof that prayer can change physical matter.

I actually thought it was God that changed physical matter if He agreed with our prayer requests, and not our prayers themselves, because if it was simply our prayer, then we wouldn’t need God. That’s probably a blog for another time. Still, it was her last statement that caught my attention. Intentional thought can change the properties of laser! I’d never heard that before! I had to find the references.

It turns out that the paper Dr Leaf is referring to is, “Testing nonlocal observation as a source of intuitive knowledge” [1]. In this experiment, Dr Dean Radin, a paranormal researcher, took 5 “experienced meditators” and 5 normal control subjects, and asked them to mentally interfere with a laser beam pointed at a light-reading CCD sensor inside a sealed box. He averaged out the intensity of the light pattern that was read by the CCD. He believed he found a difference in the amount of light that was read by the sensor when the meditators “blocked” the laser light compared to non-meditators and control runs.

In his original paper, Radin published the following graph of his results.

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The length of the bars represent a statistical value based on the results, not the actual results of the experiments. The simplest explanation is that the further down the bar goes, the greater the degree of interference to the laser light. Radin believed the effect was caused by the meditators literally interfering with the quantum mechanics of the photons in the laser beam, “observing” them from outside of the box, thus causing their wave function to collapse and stopping them from reaching the sensor.

However, notice that the first few experiments show a large effect, but that this diminishes as the experiments go along, and towards the end, the control groups and the meditator group is actually about the same, with no interference to the laser light at all. This effect is called the Decline Effect, and is common problem amongst studies of the paranormal. It’s a result of a phenomenon called ‘regression to the mean’, or in other words, the more times you perform an experiment, the more likely the results will line up with the true average. I think in Radin’s case, it also had a lot to do with his own expectations.

Radin himself was honest enough to discuss the effect in his paper. In his own words, “Although I had employed numerous design features to avoid artifacts (sic), and only four of the 10 control sessions conducted to that point had gone in the predicted direction, I still found it difficult to believe that the experimental effect was as easily repeatable as the results were suggesting. I knew that if I had trouble believing it, I could hardly expect anyone else to accept these results. So I found that my intentions for the experiment changed – I no longer hoped to observe results solely in the predicted direction, but rather I found myself hoping that some of the remaining sessions would go against the prediction, to validate that the methodology was not biased.” [1]

So, Radin probably caused the effect by wanting to see it. He excluded data that didn’t suit his hypothesis, citing a technical issue with the equipment, and instead focussed on the data set that still seemed to fit. He also performed the analysis of the data, which he biased with his own pre-conceived notions.

The other nail in the coffin for this paper is that it was a pilot study that was done by one researcher, which no one has since tried, or succeeded in, replicating. Indeed, the methodology for this research was based on a series of experiments done by a real physicist with better equipment, Professor Stanley Jeffers, a professor of physics at York University in Toronto, Canada, who performed the experiment about 74 times and found no effect [2].

So, Dr Leaf has cited this isolated, error prone, biased and unconfirmed paper of Radin’s as proof of the ability of thought to change physical matter, and indeed, as prayer’s ability to change physical matter.

This is simply more proof that Dr Leaf is prone to rush in where angels fear to tread, and latch on to any “research” that supports her ideas, no matter how tenuous or unscientific. She did the same thing when she cited a conference poster from a paranormal conference in the early 90’s, and claimed it was definitive proof that our thoughts can change our DNA. In actual fact, the paper was so full of flaws [3: Ch 13, The “ingenuous” experiment] that the only thing it could show was how desperate Dr Leaf is to try and justify her unscientific pet theories.

This tendency for Dr Leaf to rely on such poor science, and link it to fundamental Biblical concepts, dishonours science, the truth of the Bible, and her audience.

I think Dr Leaf would be wise to review her scientific philosophy and the “research” that she uses to justify it, rather than continuing to utilise tenuous and inaccurate articles from studies of the paranormal.


[1]        Radin D. Testing nonlocal observation as a source of intuitive knowledge. Explore 2008 Jan-Feb;4(1):25-35.

[2]        Alcock JE, Burns J, Freeman A. Psi wars: Getting to grips with the paranormal: Imprint Academic Charlottesville, VA, 2003.

[3]        Pitt CE. Hold That Thought: Reappraising the work of Dr Caroline Leaf. 1st ed. Brisbane, Australia: Pitt Medical Trust, 2014.

Aspartame. Is it more ‘Die’ than ‘Diet’?

A link came around tonight on my Facebook feed about aspartame: “Aspartame is linked to Leukemia and Lymphoma in new Landmark Study on Humans” (http://worldtruth.tv/aspartame-is-linked-to-leukemia-and-lymphoma-in-new-landmark-study-on-humans/)

I’ve seen these sorts of articles come around on social media before, usually in the form of an alternative health website hysterically exaggerating an irrelevant or pseudoscientific study, trying to prove some point about the evils of western medicine or society, or get more internet traffic through sensationalist click-bait.

And I’d heard the whole aspartame-causes-cancer thing before. I’d heard that there was maybe some evidence in animal studies, but that there was no definitive link in humans.

So just from the title, before I’d even read the article, my sceptical mind was primed to expect the opposite of the articles eye-catching headline.  I started searching the literature to see if there was any evidence to prove me right.

The first research article I came across that wasn’t on rats was from the American Journal of Clinical Nutrition in 2012, “Consumption of artificial sweetener – and sugar-containing soda and risk of lymphoma and leukemia in men and women” [1]. It was an impressive study in terms of its numbers and its quality. It was drawn from the data of the Nurses Health Study and the Health Professionals Follow-Up Study, which were both prospective studies (which follow a large number of subjects over a long time to see who gets the disease in question, rather than starting with who has the disease in question and trying to work backwards trying to ascertain causes, which is much less reliable). Both studies also had a large number of subjects which increased their statistical power, and made their findings more robust.

The results didn’t look very good for aspartame. There was a clear-cut increase in the risk of Non-Hodgkins Lymphoma for men who consumed two or more serves per day of diet drinks containing aspartame (Relative Risk: 1.69; 95% Confidence Interval: 1.17, 2.45; P-trend = 0.02) and Multiple Myeloma for men who consumed one or more serve per day of diet drinks containing aspartame (RR: 2.02; 95% CI: 1.20, 3.40). However, there was no change in the risks for women who consumed aspartame.

The results certainly caught me a little off guard. Perhaps there was some truth to the alternative website’s assertions after all. Interestingly enough, the study that the worldtruth.tv site reviewed was the same article I’d found. I was guilty of making a snap judgement, and I had to remind myself not to always jump to conclusions.

Still, even though the article wasn’t sensationalist click-bait, some unanswered questions remained. Why was the risk only found in men? Was there a real association, and if so, why the difference. Should we extrapolate this finding like worldtruth.tv did and justifiably ask “will future, high-quality studies uncover links to the other cancers in which aspartame has been implicated (brain, breast, prostate, etc.)?”

In terms of the gender difference, the authors of the original study did have a theory: “We hypothesized that the sex differences we observed may have been due to the recognized higher enzymatic activity of alcohol dehydrogenase type I (ADH) in men, which possibly induced higher conversion rates from methanol to the carcinogenic substrate formaldehyde.” In support of this theory, they looked at the risk of leukaemia and lymphoma in those aspartame users who were drinkers vs the aspartame users who weren’t. Ethanol stops the metabolic conversion of aspartame to formaldehyde, so if their theory was on the right track, those aspartame users who also drank alcohol would have a lower risk. As it turns out, their data was supportive, with aspartame non-drinkers having an increased risk for Non-Hodgkins Lymphoma (RR: 2.34; 95% CI: 1.46, 3.76; P-trend = 0.004) compared with aspartame users who also drank (RR: 0.96; 95% CI: 0.48, 1.90; P-trend = 0.99) [1].

However, despite the findings of Schernhammer et al, a more recent large prospective trial published in the Journal of Nutrition last year found there was no association between soft-drinks of any variety and blood cancers, including those containing aspartame [2].

So the jury is still out on aspartame. Based on what we currently know, if you’re a woman, then there’s no risk of developing leukaemia or lymphoma from drinking diet drinks. If you’re a man, there’s also probably no risk, but a glass or two of alcohol a day would probably make sure of that. Although the best advice is probably to not bother drinking diet drinks at all. The best diet drink is still plain old water, which has virtually no associated risks, is much cheaper, and probably tastes a whole lot better.


  1. Schernhammer, E.S., et al., Consumption of artificial sweetener- and sugar-containing soda and risk of lymphoma and leukemia in men and women. Am J Clin Nutr, 2012. 96(6): 1419-28 doi: 10.3945/ajcn.111.030833
  2. McCullough, M.L., et al., Artificially and sugar-sweetened carbonated beverage consumption is not associated with risk of lymphoid neoplasms in older men and women. J Nutr, 2014. 144(12): 2041-9 doi: 10.3945/jn.114.197475

Why all the anger?

One of the latest vaccination memes to go viral on social media is an article by Arizona “paleo-cardiologist”, Dr Jack Wolfson.

Dr Wolfson did an interview with one of his local TV stations in January, during which he gave his opinion about the outbreak of measles centred around Disneyland.

He said, “We should be getting measles, mumps, rubella, chicken pox, these are the rights of our children to get it. We do not need to inject chemicals into ourselves and into our children in order to boost our immune system. I’m a big fan of what’s called paleo-nutrition, so our children eat foods that our ancestors have been eating for millions of years. That’s the best way to protect.” (http://www.azcentral.com/story/news/12-news/2015/01/23/12news-doctor-dont-vaccinate/22200535/)

His follow up article, the one going viral, is titled, “Why All the Anger?” Uh … how about because you’re a douche?

Let’s start by looking at his comments in January on Arizona’s Channel 12 News:

  1. “We should be getting measles, mumps, rubella, chicken pox, these are the rights of our children to get it”.
    Or in other words, by stopping our children getting sick, we’re depriving them of their rights. That’s a patently stupid statement. Our children have a right to expect care. We give them shelter, protection, education and good nutrition so that their lives can flourish. Vaccinations are part of that care. Sure, there are side effects of vaccines, but they are nothing compared to the abject cruelty of the diseases they prevent.
  1. “We do not need to inject chemicals into ourselves and into our children in order to boost our immune system.”
    Our immune systems do an amazing job at keeping us alive. Our immune systems will eventually fight off measles, chicken pox, or any other number of pathogens, but vaccines stop the “collateral damage”, the children who are overwhelmed by the full-blown infection and die, or are permanently disabled by it. Even for the children that come through ‘unscathed’ (i.e. not dead), illnesses like measles inflict weeks of suffering with high fevers, aching joints and muscles, severe fatigue, and any other number of symptoms, then there are the ongoing illnesses like shingles and the associated severe chronic nerve pain from viruses like chickenpox, all of which can be prevented by routine childhood vaccinations.
  1. “I’m a big fan of what’s called paleo-nutrition, so our children eat foods that our ancestors have been eating for millions of years. That’s the best way to protect.”
    Really? The Palaeolithic population were hunter-gatherers, and we know that the mortality of hunter-gatherer children is in the order of 40% (http://cast.uark.edu/local/icaes/conferences/wburg/posters/sara_stinson/stinson.html). That’s not what I would call ‘protective’. Besides, palaeontologists have shown that the food promoted as ‘paleo’ is nothing like the food that our ancestors ate (https://www.youtube.com/watch?v=BMOjVYgYaG8) so paleo-nutrition is just another baseless fad.

I’m guessing that the response he received after publically sharing his heterodox views wasn’t particularly favourable. In reply, he offered this article, which is the article now going viral on social media (http://healthimpactnews.com/2015/arizona-cardiologist-responds-to-critics-regarding-measles-and-vaccines/).

It seems to me like he has unsuccessfully tried to dig himself out of his own grave. Sure, those people who are also currently drinking the antivaccine-paleo Kool-Aid will take his side and point to this brave martyr standing up to the establishment, but ultimately his come-back is nothing more than diversionary blame-shifting.

Here’s what he had to say about who the real enemies are:

“1. Be angry at food companies. Sugar cereals, donuts, cookies, and cupcakes lead to millions of deaths per year. At its worst, chicken pox killed 100 people per year. If those chicken pox people didn’t eat cereal and donuts, they may still be alive. Call up Nabisco and Kellogg’s and complain. Protest their products. Send THEM hate-mail.
2. Be angry at fast food restaurants. Tortured meat burgers, pesticide fries, and hormone milkshakes are the problem. The problem is not Hepatitis B which is a virus contracted by drug users and those who sleep with prostitutes. And you want to inject that vaccine into your newborn?
3. Be angry at the companies who make your toxic laundry detergent, fabric softener, and dryer sheets. You and your children are wearing and breathing known carcinogens (they cause cancer). Call Bounce and Downy and let them know. These products kill more people than mumps, a virus which actually doesn’t cause anyone to die. Same with hepatitis A, a watery diarrhea.
4. Be angry at all the companies spewing pollution into our environment. These chemicals and heavy metals are known to cause autism, heart disease, cancer, autoimmune disease and every other health problem. Worldwide, these lead to 10’s of millions of deaths every year. Measles deaths are a tiny fraction compared to pollution.
5. Be angry at your parents for not breastfeeding you, co-sleeping with you, and stuffing your face with Domino’s so they can buy more Tide and finish the laundry. Breastfeeding protects your children from many infectious diseases.
6. Be angry with your doctor for being close-minded and not disclosing the ingredients in vaccines (not that they read the package insert anyway). They should tell you about the aluminum, mercury, formaldehyde, aborted fetal tissue, animal proteins, polysorbate 80, antibiotics, and other chemicals in the shots. According to the Environmental Working Group, newborns contain over 200 chemicals as detected by cord blood. Maybe your doctor feels a few more chemicals injected into your child won’t be a big deal.
7. Be angry with the cable companies and TV manufacturers for making you and your children fat and lazy, not wanting to exercise or play outside. Lack of exercise kills millions more than polio. Where are all those 80 year olds crippled by polio? I can’t seem to find many.
8. In fact, be angry with Steve Jobs and Bill Gates for creating computers so you can sit around all day blasted with electromagnetic radiation reading posts like this.
9.Be angry with pharmaceutical companies for allowing us to believe living the above life can be treated with drugs. Correctly prescribed drugs kill thousands of people per year. The flu kills just about no one. The vaccine never works.

Finally, be angry with yourself for not opening your eyes to the snow job and brainwashing which have taken over your mind. You NEVER asked the doctor any questions. You NEVER asked what is in the vaccines. You NEVER learned about these benign infections.

Let’s face it, you don’t really give a crap what your children eat. You don’t care about chemicals in their life. You don’t care if they sit around all day watching the TV or playing video games.

All you care about is drinking your Starbuck’s, your next plastic surgery, your next cocktail, your next affair, and your next sugar fix!”

Yes, it’s all your fault. You’re all too selfish to see how you’ve been conned by centuries of scientific evidence, and that only those who follow the doctrines of paleo-nutrition are truly enlightened.

It would be funny if it wasn’t so serious. This so-called man of science would have us believe that measles, chickenpox, diphtheria, polio and other vaccine preventable diseases are benign. Tell that to the 2.5 million children who die every year from vaccine-preventable diseases around the world (De Cock, Simone, Davison, & Slutsker, 2013).

“At its worst, chicken pox killed 100 people per year.” According to the CDC, his figure is correct – the average number of deaths from chickenpox from 1990-1996 was about 103 per year in the USA though he failed to mention the 11,000 hospitalisations per year caused by chickenpox (http://www.cdc.gov/vaccines/pubs/pinkbook/downloads/varicella.pdf). Measles, on the other hand, kills two people for every thousand that are infected by it (http://www.cdc.gov/vaccines/pubs/pinkbook/meas.html#complications). The 2013 US road toll was 0.107/1000 (http://www.cdc.gov/nchs/fastats/accidental-injury.htm), making measles 18 times more deadly than road transportation.

“Where are all those 80 year olds crippled by polio? I can’t seem to find many.” Well, it’s hard to find anything when you’re closed minded. Polio caused paralysis in about 1 in 100 cases, and death in up to 30% of those (http://www.cdc.gov/vaccines/pubs/pinkbook/polio.html). Again, those figures are worse than the road toll.

“Be angry with your doctor for being close-minded and not disclosing the ingredients in vaccines (not that they read the package insert anyway). They should tell you about the aluminum, mercury, formaldehyde, aborted fetal tissue, animal proteins, polysorbate 80, antibiotics, and other chemicals in the shots”. Guess what, your doctor doesn’t tell you about aluminum, mercury, formaldehyde, aborted fetal tissue, animal proteins, polysorbate 80, antibiotics etc in vaccines because they’re either not there, or they’re there in amounts so tiny that you would have a greater exposure to them by simply eating. For example, Thiomersal (which contained mercury) has been removed from childhood vaccines since the year 2000 as a precautionary measure, even though there was never any evidence it caused any harm. Aluminium from vaccines is lower than everyday exposure from intake from diet or medications, such as antacids, and is well below the levels recommended by organisations such as the United States Agency for Toxic Substances and Disease Registry. And there is no aborted foetal tissue in vaccines (http://www.health.gov.au/internet/immunise/publishing.nsf/content/uci-myths-guideprov)

And the rest … more of the usual rhetoric of the paleo-minded – sugar, “tortured meat” burgers, “pesticide” fries, and “hormone” milkshakes, laundry detergent, pollutants that “cause autism, heart disease, cancer, autoimmune disease and every other health problem”, computers that bombard you with electromagnetic radiation … he even goes a little Freudian by blaming mothers for not breast feeding and co-sleeping enough. It’s all a bit of a stretch.

So why all the anger? Maybe it has something to do with the fact that people are sick and tired of so-called experts trying to debase solid science with some tarted up pseudoscientific fad. The public know more than what most snake-oil salesmen think they do, and they’re sick of being treated like idiots. People know that immunisation works, and trying to sell the idea that ‘paleo-nutrition’ is better than vaccination just makes you look like a douche.


De Cock, K. M., Simone, P. M., Davison, V., & Slutsker, L. (2013). The new global health. Emerg Infect Dis, 19(8), 1192-1197. doi: 10.3201/eid1908.130121

Dr Caroline Leaf – Scientific heresy

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Imagine that this Easter, the guest speaker at your church stands up from the pulpit and calmly mentions during the sermon that Jesus wasn’t really buried in a tomb, but was kept by his disciples in a house until he recovered enough from his wounds to go on his merry way.

What would you think of that speaker? Would you smile and nod, or even shout an ‘amen!’, buy their book, and encourage your pastor that they should be invited back again?

One would hope that there would be a polite but resounding outcry. Even if the rest of the message was perfect, you wouldn’t want someone to come back to your pulpit if they couldn’t get the basics of their subject right, even if they were considered a popular speaker or self-declared expert.

Dr Caroline Leaf is a communication pathologist and self-titled cognitive neuroscientist. Dr Leaf preaches every day from both physical pulpits all over the globe, and a virtual pulpit through the power of Instagram and Facebook.

Dr Leaf used her position of social media prominence today to share this little jewel, “The brain cannot change itself; you, with your love power and sound mind, change your brain.”

Um … that’s not true … at all … in any way.

For a start, the most prolific period for brain development is actually pre-birth, and then the first year of life. But foetal brains don’t have their own thoughts. It’s not like the movie “Look Who’s Talking” inside the average uterus. The brain of an unborn baby is growing and changing at an exponential rate without any thoughts to guide them [1].

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Number of synapses per constant volume of tissue as a function of pre- and postnatal age. (Stiles, J. and Jernigan, T.L., The basics of brain development. Neuropsychol Rev, 2010. 20(4): 327-48 doi: 10.1007/s11065-010-9148-4)


In our adult years, our brain still continues to develop. But that development isn’t dependant on our thought life. Significant consolidation of our brain’s neural pathways occur when we’re asleep [2], but our thought life isn’t active during sleep.

Model of sleep stage-specific potentiation and homeostatic scaling. Gronli, J., et al., Sleep and protein synthesis-dependent synaptic plasticity: impacts of sleep loss and stress. Front Behav Neurosci, 2013. 7: 224 doi: 10.3389/fnbeh.2013.00224

Model of sleep stage-specific potentiation and homeostatic scaling. (Gronli, J., et al., Sleep and protein synthesis-dependent synaptic plasticity: impacts of sleep loss and stress. Front Behav Neurosci, 2013. 7: 224 doi: 10.3389/fnbeh.2013.00224)

Indeed, real cognitive neuroscientists have shown that our stream of thought is simply a tiny fraction of our overall neural activity, a conscious glimpse of the brains overall function [3-5]. So you don’t change your brain at all. “You” can’t, because it’s your brain’s directed activity which causes the growth of new synaptic branches to support it, all of which is subconscious.

Therefore, suggesting that our brain can only change with our conscious control is patently false, and so clearly against the most fundamental principles of neuroscience that such a claim is the neuroscientific equivalent of saying that Jesus didn’t die on the cross, he just swooned.

Dr Leaf has committed scientific heresy.

At this point, supporters of Dr Leaf often suggest that she wasn’t speaking literally, but metaphorically. She didn’t really mean that the brain can’t change itself, just that our choices are really important.

Somehow I doubt that. Dr Leaf wasn’t being metaphorical when she claimed that her patients in her research projects grew their intelligence when they “applied their minds”:
“Now with a traumatic brain injury, basically IQ generally goes down around twenty points because of the kind of damage with traumatic brain injury. Well her IQ was 100 before the accident, it was 120 after the accident. So here with holes in her brain, and brain damage, she changed … she actually increased her intelligence. Now I’m pretty convinced at this stage, cause I’ve been working … besides her I’ve been working with lots and lots of other patients, seeing the same thing, when these students applied their mind, their brain was changing, their academic results were changing.” [6]

Dr Leaf believes that your mind can literally change your brain. It was the subject of her entire TEDx talk in February.

It sounds innocent enough until you consider the broader implications of this way of thinking – those with brain damage haven’t recovered fully because they just haven’t applied their minds enough. The same for those with learning disabilities or autism, ADHD, Downs syndrome, cerebral palsy, dyslexia, or any other neurological disorder … because you only need to “apply your minds” to change your brain. “You have a powerful mind. You have a sound mind. You have a mind that is able to … to achieve what you’re dreams are. You are as intelligent as you want to be.” [6]

Or, in other words, don’t blame it on your brain if you’re intellectually disabled, mentally ill, or vacuous. You simply haven’t applied your brain well enough. Stop sitting around and think better.

As a church, we can, and should, be doing a lot better for those amongst us who suffer from neurological and mental disorders. It starts by being more judicious with who is allowed at that privileged position of the pulpit. We need to be eliminating scientific heresy from the pulpit, not clapping and shouting ‘amen!’


  1. Stiles, J. and Jernigan, T.L., The basics of brain development. Neuropsychol Rev, 2010. 20(4): 327-48 doi: 10.1007/s11065-010-9148-4
  2. Gronli, J., et al., Sleep and protein synthesis-dependent synaptic plasticity: impacts of sleep loss and stress. Front Behav Neurosci, 2013. 7: 224 doi: 10.3389/fnbeh.2013.00224
  3. Baars, B.J., Global workspace theory of consciousness: toward a cognitive neuroscience of human experience. Progress in brain research, 2005. 150: 45-53
  4. Baars, B.J. and Franklin, S., An architectural model of conscious and unconscious brain functions: Global Workspace Theory and IDA. Neural Netw, 2007. 20(9): 955-61 doi: 10.1016/j.neunet.2007.09.013
  5. Franklin, S., et al., Conceptual Commitments of the LIDA Model of Cognition. Journal of Artificial General Intelligence, 2013. 4(2): 1-22
  6. Leaf, C.M., Ridiculous | TEDx Oaks Christian School | 4 Feb 2015, 2015 TEDx, 20:03. https://http://www.youtube.com/watch?v=yjhANyrKpv8

Dr Caroline Leaf – It’s no joke

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So, stop me if you’ve heard this one … This guy walks into a bar, and says, “Owww, that bar is really hard.”

Ok, that was a bad joke. Hey, I’m no Robin Williams. Some people have the knack of being able to make people laugh in almost any situation. I can get a few laughs, but I’m not a naturally gifted comic.

Dr Caroline Leaf is a communication pathologist and a self-titled cognitive neuroscientist. She isn’t a comedian either.

Her post today was a light-hearted dig at giant lizards with a taste for organic free-range humans, or perhaps the fact that most people know being “all organic, gluten free” should be left to the sanctimonious foodies of San Francisco.

The other part of her post wasn’t meant to be funny, but certainly contained a healthy dose of irony. In trying to justify her bit of light comic relief, she posted another of her subtly erroneous factoids, this time claiming that, “Laughing 100-200 times a day is equal to 10 minutes of rowing or jogging!”

Not according to real scientists, who have worked out that laughing is actually the metabolic equivalent to sitting still at rest, while jogging or rowing burns between 6 to 23 times as much energy, depending on how fast you run or row [1].

That would mean that I would have to laugh for at least a whole hour a day (or about 700 times based on the average chortle) to be even close to the energy burnt by a light jog.

On the grand scale of things, this meme probably doesn’t really matter. These sort of factoids are thrown around on social media all the time, and it won’t make a big difference to the health and wellbeing of most people. But it does help establish a pattern. Dr Leaf habitually publishes memes and factoids that clearly deviate from the scientific truth, proving that Dr Leaf has become a cross between a science fiction author and life coach, not a credible scientific expert. From her social media memes to her TV shows, all of her teaching becomes tainted as untrustworthy.

While today’s meme may not be so serious, if Dr Leaf can’t get her facts straight, pretty soon the joke will be on her.


  1. Ainsworth, B.E., et al., 2011 Compendium of Physical Activities: a second update of codes and MET values. Med Sci Sports Exerc, 2011. 43(8): 1575-81 doi: 10.1249/MSS.0b013e31821ece12

Fats and Figures: Re-examining saturated fat and what’s really good for your heart

Fats and Figures cover 1400

A Facebook friend forwarded me an article a few weeks back and asked for my humble medical opinion.

The article was entitled, “World Renowned Heart Surgeon Speaks Out On What Really Causes Heart Disease”. It was written by a man who said he was a heart surgeon, and who claimed to be coming clean on the real reason why our world has an epidemic of obesity and heart disease despite the low fat advice of the medical profession.

It’s a highly controversial topic right now. For decades, the western world was under the impression that fat was tobaccos right hand man in a war on good health. Standard medical dogma was that high cholesterol was bad, and that saturated fat was its main source. Evil butter was replaced with angelic margarine. Fatty red meat was always served with a generous side portion of guilt. Low fat became high fashion.

Today, the pendulum of public opinion has swung back with such amazing ferocity, it’s become more like a wrecking ball. Fat has returned to the fold as friend instead of foe. The once mighty cholesterol lowering medications called statins have become seen as another example of pharmaceutical company profits-before-patients. Sugar has become the new villain, and along with it, the nebulous concept of “inflammation” as the key mechanism of heart disease and strokes, and nearly every other medical ailment.

What started off as a three-paragraph reply on Facebook has evolved into a short eBook, which you can download for free from Smashwords (https://www.smashwords.com/books/view/514719)

In today’s post, I want to look at six things that, over the years, have been touted as contributing to or preventing heart disease, and see what the evidence says. The results may be surprising!

1. Is saturated fat bad? Is polyunsaturated fat good?

According to a meta-analysis of observational studies on dietary fats by Chowdhury et al. (2014), relative risks for coronary disease were 1.02 (95% CI, 0.97 to 1.07) for saturated fats, 0.99 (CI, 0.89 to 1.09) for monounsaturated, 0.93 (CI, 0.84 to 1.02) for long-chain n-3 polyunsaturated, 1.01 (CI, 0.96 to 1.07) for n-6 polyunsaturated, and 1.16 (CI, 1.06 to 1.27) for trans fatty acids. The total number of patients in all of the trials was more than half a million. This is pretty convincing evidence that saturated fats aren’t as bad as first believed.

What does all this mean? In statistical terms, a relative risk is the incidence of disease in one group compared to the incidence of disease in another. The risk of the disease in the two groups is the same if the relative risk = 1. A relative risk of 7.0 means that the experiment group has seven times the risk of a control group. A relative risk of 0.5 would mean the experiment group has half the risk of the control group. The confidence interval is a range of numbers in which there is a 95% chance that the true relative risk is in the interval. A result is “statistically significant” when the confidence interval (CI) does not cross the number 1.

So going back to the study by Chowdhury et al. (2014), only 2% more patients in the group with the highest saturated fat consumption had heart disease compared to the lowest saturated fat consumption. The confidence interval crossed 1, so that result may have been due to chance alone. For trans fatty acid consumption, 16% more people had heart disease in the higher consumption group compared to the lower consumption group, which was probably a real effect and not due to chance (the confidence interval did not cross 1). Simply put, trans-fats are bad. Saturated fats probably aren’t.

The same meta-analysis by Chowdhury et al. (2014) also reviewed supplementation with PUFA’s on the overall risk of heart disease. They found that in 27 randomised controlled trials with more than 100,000 people, relative risks for coronary disease were 0.97 (CI, 0.69 to 1.36) for alpha-linolenic acid supplements, 0.94 (CI, 0.86 to 1.03) for long-chain n-3 polyunsaturated acid supplements, and 0.89 (CI, 0.71 to 1.12) for n-6 polyunsaturated fatty acid supplements. In this case, there was a trend in favour of supplementation with omega-3 and omega-6 supplements, but it was small, and may have been due to chance. This is confirmed by other reviews (Rizos, Ntzani, Bika, Kostapanos, & Elisaf, 2012; Schwingshackl & Hoffmann, 2014)

So it appears that it doesn’t matter what fat you consume, saturated or polyunsaturated, or whether you supplement with fish oils or eat lots of fish, your cardiovascular risk is much the same. The only thing that’s definitely clear is that you should avoid trans-fats.

2. Is sugar bad for you?

That depends.

When we think of sugar, we think of sucrose, a carbohydrate made up of one glucose and one fructose molecule. There are many carbohydrates, which are just various combinations of different numbers of glucose/fructose molecules, sucrose being one type.

Sugar consumption is thought to be the modern scourge, it’s consumption linked to everything from cancer to gallstones. It’s been recently become the villain of cardiovascular disease as well. It’s thought to cause insulin resistance, inflammation and an increase in the fats circulating in the blood stream. So, is it as bad as they say? The evidence is surprising.

First of all, sugar doesn’t make you fat. Rather, it’s the calories you consume that make you fat. Te Morenga, Mallard, and Mann (2013) conclude their meta-analysis of dietary sugar and body weight, “Among free living people involving ad libitum diets, intake of free sugars or sugar sweetened beverages is a determinant of body weight. The change in body fatness that occurs with modifying intakes seems to be mediated via changes in energy intakes, since isoenergetic exchange of sugars with other carbohydrates was not associated with weight change.”

The intake of sugar and glucose don’t cause an increase in inflammation or cholesterol in healthy people. In a study on effects of sugar consumption on the biomarkers of healthy people, Jameel, Phang, Wood, and Garg (2014) found that consumption of sucrose and glucose actually decreased cholesterol. Fructose increased cholesterol, though interestingly, the Total:HDL ratio (which is prognostic for heart disease) did not change significantly with the consumption of any form of sugar. They also found that fructose was associated with an increase in inflammation, but glucose and sucrose reduced inflammation.

On the other hand, a study by Isordia-Salas et al. (2014) showed a small but significant association between those with high blood glucose level and inflammation, though they also found an association between inflammation and BMI (the body-mass index), so it’s not clear what the causal factor is.

There seems to be a clearer association between blood glucose after meals in those who have abnormal glucose metabolism. In patients with pre-diabetes, higher levels of blood glucose two hours after eating were associated with increased risk of death from cardiovascular disease and all causes (Coutinho, Gerstein, Wang, & Yusuf, 1999; Decode Study Group, 2003; Lind et al., 2014).

To melt your brain a little more, just because high glucose levels are associated with higher mortality doesn’t mean the lower the glucose, the better. In the study by the Decode Study Group (2003), low blood glucose had a higher mortality than normal glucose levels, and a meta-analysis by Noto, Goto, Tsujimoto, and Noda (2013) showed that low carbohydrate diets have a 30% increase in all-cause mortality.

How do you pull all of these seemingly contradictory studies together? The bottom line appears to be, according to the evidence so far, that consumption of sugar does not cause inflammation or significantly increase the risk of heart disease in healthy people who are able to metabolise it properly.

In those people who have abnormal glucose metabolism, the higher the glucose is after a meal (a measure of how well the body processes glucose), then the higher the risk is of inflammation, heart disease, and all-cause mortality.

The distinction between who has normal glucose metabolism and who has dysfunctional glucose metabolism is probably related to genetics. A study by Sousa, Lopes, Hueb, Krieger, and Pereira (2011) showed that genetic information was able to predict 5-year incidence of major cardiovascular events and overall mortality in non-diabetic individuals, even after adjustment for the persons blood sugar. Those without diabetes but who had a high genetic risk had a similar incidence of cardiovascular events compared to diabetics. So if you have the genes, your body doesn’t process the glucose properly and your risk is increased, even if you aren’t bad enough to have a diagnosis of diabetes.

Thus it appears that sugar is not the bad guy that everyone makes it out to be. Excess sugar will make you fat, but so will excess everything-else. It probably won’t kill you unless you’re genetically pre-disposed to handle it poorly. And there’s the rub, because we don’t have the capacity to test for that clinically yet.

So the last word on sugar is that it’s a sometimes food. You may be lucky enough to handle large amounts of sugar, but the best advice at this time is don’t tempt fate by eating large quantities of it.

3. Is obesity bad for you?

Again, that depends.

It used to be thought that obesity posed a linear risk, that is, the fatter you were the higher your risk of heart attacks, cancer, diabetes, everything. Then in 2013, a meta-analysis by Flegal, Kit, Orpana, and Graubard (2013) showed that people who were overweight (but not obese) had better survival than those who were normal weight.

Later in 2013, Kramer, Zinman, and Retnakaran (2013) published a meta-analysis which showed that metabolically unhealthy people of normal BMI were at greater risk of cardiovascular disease than metabolically healthy obese people.

Last year a paper by Barry et al. (2014) showed that those who were unfit were twice as likely to die compared to people who were fit, irrespective of their BMI.

So obesity doesn’t seem to be the problem after all, rather it’s a persons ability to handle blood sugar, cholesterol and blood pressure that’s the problem. It seems that more people with obesity have these metabolic problems, but correlation does not equal causation. There’s probably a undetermined factor that links obesity and metabolic dysfunction.

I’m not suggesting that we should all get fatter. Obesity has problems of its own, unrelated to metabolic issues, that make it problematic. We should still be careful about our weight. The take-home message is that skinny does not necessarily mean healthy and that focusing on what the scales are saying may be distracting us from the real problem.

4. Is meat bad for you? Should we be vegetarians?

In a word, no.

In the two available meta-analyses of the studies on red meat consumption (Larsson & Orsini, 2014), and red meat vs white meat vs all meat (Abete, Romaguera, Vieira, Lopez de Munain, & Norat, 2014), there was a statistical but moderate increase in death and heart disease from processed meats.

There was a trend towards a higher death rate in those who ate the most red meat, but the trend wasn’t statistically significant (i.e.: may have been related to chance). There was no trend associated with white meat consumption. So it appears that as long as it’s not processed meat, red meat isn’t as bad as people first thought.

Meat might not be particularly bad, but are vegetarian diets better? Again, probably not. The meta-analysis by Huang et al. (2012) shows that there’s a positive trend for vegetarian diets, though again, that might be attributable to chance as the results are not statistically significant.

The take-away message? Even though the trends may be related to chance, the trend is favourable for vegetables and not as favourable for red meat. So eat more veggies, eat less red meat, but don’t let some sanctimonious vegan convince you that meat is noxious and vile.

5. Is alcohol good for you?

A different meme recently came around my Facebook feed, entitled, “Is Drinking Wine Better Than Going To The Gym? According To Scientists, Yes!” For a while there, I had fantasies about giving my membership card back to the gym and heading down to the local bottle shop for my daily workout instead.

Disappointingly, it turns out that red wine isn’t better than exercise according to the research that I uncovered. However, my research did suggest that the daily exercise of wine drinking is still beneficial, and not just red wine, but alcohol of any form. Ronksley, Brien, Turner, Mukamal, and Ghali (2011) showed about two standard drinks of alcohol daily conferred a 25% reduction in deaths from heart disease (relative risk 0.75 (0.68 to 0.81)), and a small but statistically strong reduction in death from all causes of 13% (relative risk 0.87 (0.83 to 0.92)). The risk reduction of coronary heart disease from alcohol was also confirmed in a more recent study by Roerecke and Rehm (2014), who showed that death from heart disease was reduced by 36% for those who consistently consumed less than three standard drinks a day (relative risk 0.64 (0.53 to 0.71)).

The effect applies to consistent daily consumption, not to drinking in a cluster pattern (binging or weekend-drinking only, for example). And there’s a gender difference, women having the maximum beneficial effect at about one drink a day, and two drinks a day in men.

6. Is exercise good for you?

In a word, yes!

I’ve never seen a study that showed exercise was harmful. Exercise improves overall metabolism, decreases cardiovascular disease, improves mood and memory and increases your lifespan, amongst many other things. If exercise came in pill form, it would be labelled a wonder-drug.

As discussed earlier, fit people have a better rate of survival compared to unfit people, whether they’re obese or not (Barry et al., 2014). And the key to fitness is exercise. In a large meta-analysis by Samitz, Egger, and Zwahlen (2011), 80 studies involving more than 1.3 million subjects in total were analysed, showing that the highest levels of exercise had an all cause mortality reduction of 35% (relative risk 0.65 (0.6 to 0.71)).

There’s always debate about what form of exercise is best. Are you better to do weights, do interval training, or run for hours? Honestly, it probably doesn’t matter that much in the end. What is important is that you work hard enough to elevate your heart rate and break a sweat. If you aren’t very fit, it won’t take much exercise to do that. If you are very fit, it probably will. But for the average person, you don’t have to jump straight into a boot camp style program and work so hard that you’re puking everywhere, and so sore afterwards that you can’t move for a week. Common sense prevails!


Abete, I., Romaguera, D., Vieira, A. R., Lopez de Munain, A., & Norat, T. (2014). Association between total, processed, red and white meat consumption and all-cause, CVD and IHD mortality: a meta-analysis of cohort studies. Br J Nutr, 112(5), 762-775. doi: 10.1017/S000711451400124X

Barry, V. W., Baruth, M., Beets, M. W., Durstine, J. L., Liu, J., & Blair, S. N. (2014). Fitness vs. fatness on all-cause mortality: a meta-analysis. Prog Cardiovasc Dis, 56(4), 382-390. doi: 10.1016/j.pcad.2013.09.002

Chowdhury, R., Warnakula, S., Kunutsor, S., Crowe, F., Ward, H. A., Johnson, L., . . . Di Angelantonio, E. (2014). Association of dietary, circulating, and supplement fatty acids with coronary risk: a systematic review and meta-analysis. Ann Intern Med, 160(6), 398-406. doi: 10.7326/M13-1788

Coutinho, M., Gerstein, H. C., Wang, Y., & Yusuf, S. (1999). The relationship between glucose and incident cardiovascular events. A metaregression analysis of published data from 20 studies of 95,783 individuals followed for 12.4 years. Diabetes Care, 22(2), 233-240.

Decode Study Group, E. D. E. G. (2003). Is the current definition for diabetes relevant to mortality risk from all causes and cardiovascular and noncardiovascular diseases? Diabetes Care, 26(3), 688-696.

Flegal, K. M., Kit, B. K., Orpana, H., & Graubard, B. I. (2013). Association of all-cause mortality with overweight and obesity using standard body mass index categories: a systematic review and meta-analysis. JAMA, 309(1), 71-82. doi: 10.1001/jama.2012.113905

Huang, T., Yang, B., Zheng, J., Li, G., Wahlqvist, M. L., & Li, D. (2012). Cardiovascular disease mortality and cancer incidence in vegetarians: a meta-analysis and systematic review. Ann Nutr Metab, 60(4), 233-240. doi: 10.1159/000337301

Isordia-Salas, I., Galvan-Plata, M. E., Leanos-Miranda, A., Aguilar-Sosa, E., Anaya-Gomez, F., Majluf-Cruz, A., & Santiago-German, D. (2014). Proinflammatory and prothrombotic state in subjects with different glucose tolerance status before cardiovascular disease. J Diabetes Res, 2014, 631902. doi: 10.1155/2014/631902

Jameel, F., Phang, M., Wood, L. G., & Garg, M. L. (2014). Acute effects of feeding fructose, glucose and sucrose on blood lipid levels and systemic inflammation. Lipids Health Dis, 13(1), 195. doi: 10.1186/1476-511X-13-195

Kramer, C. K., Zinman, B., & Retnakaran, R. (2013). Are metabolically healthy overweight and obesity benign conditions?: A systematic review and meta-analysis. Ann Intern Med, 159(11), 758-769. doi: 10.7326/0003-4819-159-11-201312030-00008

Larsson, S. C., & Orsini, N. (2014). Red meat and processed meat consumption and all-cause mortality: a meta-analysis. Am J Epidemiol, 179(3), 282-289. doi: 10.1093/aje/kwt261

Lind, M., Tuomilehto, J., Uusitupa, M., Nerman, O., Eriksson, J., Ilanne-Parikka, P., . . . Lindstrom, J. (2014). The association between HbA1c, fasting glucose, 1-hour glucose and 2-hour glucose during an oral glucose tolerance test and cardiovascular disease in individuals with elevated risk for diabetes. PLoS One, 9(10), e109506. doi: 10.1371/journal.pone.0109506

Noto, H., Goto, A., Tsujimoto, T., & Noda, M. (2013). Low-carbohydrate diets and all-cause mortality: a systematic review and meta-analysis of observational studies. PLoS One, 8(1), e55030. doi: 10.1371/journal.pone.0055030

Rizos, E. C., Ntzani, E. E., Bika, E., Kostapanos, M. S., & Elisaf, M. S. (2012). Association between omega-3 fatty acid supplementation and risk of major cardiovascular disease events: a systematic review and meta-analysis. JAMA, 308(10), 1024-1033. doi: 10.1001/2012.jama.11374

Roerecke, M., & Rehm, J. (2014). Alcohol consumption, drinking patterns, and ischemic heart disease: a narrative review of meta-analyses and a systematic review and meta-analysis of the impact of heavy drinking occasions on risk for moderate drinkers. BMC Med, 12(1), 182. doi: 10.1186/s12916-014-0182-6

Ronksley, P. E., Brien, S. E., Turner, B. J., Mukamal, K. J., & Ghali, W. A. (2011). Association of alcohol consumption with selected cardiovascular disease outcomes: a systematic review and meta-analysis. BMJ, 342, d671. doi: 10.1136/bmj.d671

Samitz, G., Egger, M., & Zwahlen, M. (2011). Domains of physical activity and all-cause mortality: systematic review and dose-response meta-analysis of cohort studies. Int J Epidemiol, 40(5), 1382-1400. doi: 10.1093/ije/dyr112

Schwingshackl, L., & Hoffmann, G. (2014). Dietary fatty acids in the secondary prevention of coronary heart disease: a systematic review, meta-analysis and meta-regression. BMJ Open, 4(4), e004487. doi: 10.1136/bmjopen-2013-004487

Sousa, A. G., Lopes, N. H., Hueb, W. A., Krieger, J. E., & Pereira, A. C. (2011). Genetic variants of diabetes risk and incident cardiovascular events in chronic coronary artery disease. PLoS One, 6(1), e16341. doi: 10.1371/journal.pone.0016341

Te Morenga, L., Mallard, S., & Mann, J. (2013). Dietary sugars and body weight: systematic review and meta-analyses of randomised controlled trials and cohort studies. BMJ, 346, e7492. doi: 10.1136/bmj.e7492

Dr Caroline Leaf: All scare and no science?

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On her social media feed today, Dr Leaf posted a meme implying that conventionally farmed food was toxic.

Dr Caroline Leaf is a communication pathologist and self-titled cognitive neuroscientist. Anyone who’s been following Dr Leaf will know from her frequent food selfies that she is an organic convert.

Dr Leaf is welcome to eat whatever she chooses, though not content to simply push her personal belief in organic foods, Dr Leaf is now actively criticising conventional food, publishing memes on her social media posts which imply that conventional produce is poisonous.

As I’ve written before, despite Dr Leaf’s blinding passion and quasi-religious zeal for organic foods, there is no evidence that organic food is any more beneficial than conventional food (Dangour et al, 2009; Bradbury et al, 2014). Indeed, there’s no magic to a healthy food lifestyle. Eat more vegetables. Drink more water. Conventional veggies and conventional water do just fine. Sage advice, even if it doesn’t lend itself to food selfies.

While organic zealots believe they have the high ground on the topic of food safety, the published science cuts through the hype. As noted by Smith-Spangler et al (2012), there is some evidence that there may be less pesticide residue on organically grown foods, but there is no significant difference in the risk of each group exceeding the overcautious Maximum Residue Limit.

Two points on the Maximum Residue Limit that are particularly important:

  1. The Maximum Residue Limit is extremely cautious, and most food tested is well below this already overcautious limit. The Maximum Residue Limit is set to about 1% of the amount of the pesticide that has no effect on test animals.   According to a recent survey of grapes done by Choice Australia, the amount of residue was well below the Maximum Residue Limit (about 1% of the Maximum Residue Limit on average) (Choice Australia, 2014). So on the average bunch of grapes in Australia, the pesticide residue is about one ten thousandth of the level that is safe in animals, and this pattern is the same across all conventional produce. Thinking in more practical terms, “a 68 kg man would have to eat 3,000 heads of lettuce every day of his life to exceed the level of a residue that has been proven to have no effect on laboratory animals … an 18 kg boy would have to eat 534 apples every day of his life to exceed a residue level that is not dangerous to laboratory animals. And an 18 kg girl would have to eat 13,636 kg of carrots every day of her life to exceed such a level.” (ecpa.eu, 2014)

    2. Organic foods have pesticides too. Granted, this is at lower levels than their conventional counterparts, but it’s there all the same (Smith-Spangler et al, 2012). I once had a lively discussion with an organic food zealot about the pesticides in organic farming. Her argument was that organic pesticides are safe because they’re “natural” poisons. So are arsenic, cyanide, belladonna and digitalis (foxglove), but why let the truth get in the way of ones opinion. Poisons are poisons whether they’re “natural” or not. The Maximum Residue Limit applies to organic foods just the same as conventionally farmed produce for that reason.

Another interesting thing … in the Choice survey, the organic grapes had no detectable pesticides, but so did conventionally farmed grapes bought at a local green grocer. So organic food zealots can’t claim that they have a monopoly on low pesticides in their foods.

Not that having lower pesticide residues means that organic foods are necessarily safer. Organically farmed produce has a higher risk of contamination from E. coli and other potentially toxic bacteria, depending on the farming method used (Mukherjee et al, 2007; Sample, 2011).

So to bring it all together, conventional produce has levels of pesticide residues so low that it would take an extra-ordinary feat of vegetarian gluttony to exceed a level that was still found to be non-toxic in animals. The risk to human health from conventional farming with pesticides is nanoscopic. Organic foods may have less pesticide, but they have a higher risk from enterotoxigenic bacteria.

Since there is nothing to fear from conventional foods, it seems irresponsible for Dr Leaf to promote the unscientific idea that conventional foods are poisonous. One wonders why Dr Leaf would engage in a campaign of fear against healthy, nutritious foods? Personal bias perhaps, although that doesn’t bode well for her credibility as an objective scientist. Another plausible reason could be marketing. Fear sells things, that’s Marketing 101. Gardner (2008) wrote, “Fear sells. Fear makes money. The countless companies and consultants in the business of protecting the fearful from whatever they may fear know it only too well. The more fear, the better the sales.”

Posts like today’s make Dr Leaf seem like all scare and no science. Publishing images with the skull and cross bones and the word “POISON” is certainly not attempting to allay anyone’s anxiety, and that fact that it‘s directly tied to a reminder of her upcoming book on food only makes shameless promotion all the more likely. I’m sure that a Godly woman of Dr Leaf’s standing wouldn’t stoop so low as to use fear and mistruth just to make better sales, but posts like today’s open her up to legitimate questions from others regarding her credibility and her motivation.

For her sake, I hope that she tightens up her future posts, and reconsiders her stance on the science of organic and conventional foods.


Bradbury, K.E., et al., Organic food consumption and the incidence of cancer in a large prospective study of women in the United Kingdom. Br J Cancer, 2014. 110(9): 2321-6 doi: 10.1038/bjc.2014.148

Choice Australia, 2014. <http://www.choice.com.au/reviews-and-tests/food-and-health/food-and-drink/groceries/pesticide-residues-in-fruit-and-vegetables.aspx&gt;

Dangour, A. D., Dodhia, S. K., Hayter, A., Allen, E., Lock, K., & Uauy, R. (2009). Nutritional quality of organic foods: a systematic review. Am J Clin Nutr, 90(3), 680-685. doi: 10.3945/ajcn.2009.28041

European Crop Protection Agency, 2014, <http://www.ecpa.eu/faq/what-maximum-residue-level-mrl-and-how-are-they-set>

Gardner, D., The science of fear: Why we fear the things we shouldn’t – and put ourselves in greater danger; 2008, Dutton / The Penguin Group, New York

Mukherjee, A., et al., Association of farm management practices with risk of Escherichia coli contamination in pre-harvest produce grown in Minnesota and Wisconsin. Int J Food Microbiol, 2007. 120(3): 296-302 doi: 10.1016/j.ijfoodmicro.2007.09.007

Sample, I., E coli outbreak: German organic farm officially identified. The Guardian, London, UK, 11 June 2011 <http://www.theguardian.com/world/2011/jun/10/e-coli-bean-sprouts-blamed>

Smith-Spangler, C., Brandeau, M. L., Hunter, G. E., Bavinger, J. C., Pearson, M., Eschbach, P. J., . . . Stave, C. (2012). Are organic foods safer or healthier than conventional alternatives? A systematic review. Ann Intern Med, 157(5), 348-366.