Cutting through the Paleo hype

Paleo-Diet-Meal-Plan1

Fad diets come and go. One of the most popular fad diets of recent times is Paleo.

The Palaeolithic diet, also called the ‘Stone Age diet’, or simply ‘Paleo’, is as controversial as it is popular. It’s been increasing in popularity over the last few years, and has had some amazing claims made of it by wellness bloggers and celebrity chefs. Advocates like ‘Paleo’ Pete Evans of MKR fame, claim that the Palaeolithic diet could prevent or cure poly-cystic ovarian syndrome, autism, mental illness, dementia and obesity [1].

So what does the published medical literature say? Is there really good research evidence to support the vast and extravagant claims of Paleo?

About 10 months ago, I started reviewing the medical research to try and answer that very question. My review of the medical literature turned up some interesting results, and so rather than post it just as a blog, I thought I would submit it to a peer-reviewed medical journal for publication. After a very nervous 9-month gestation of submission, review, and resubmission, my article was published today in Australian Family Physician [2].

So, why Paleo, and what’s the evidence?

Why Paleo?

The rationale for the Palaeolithic diet stems from the Evolutionary Discordance hypothesis – that human evolution ceased 10,000 years ago, and our stone-age genetics are unequipped to cope with our modern diet and lifestyle, leading to “diseases of civilization” [3-9]. Thus, only foods that were available to hunter-gatherer groups are optimal for human health – “could I eat this if I were naked with a sharp stick on the savanna?” [10] Therefore meat, fruits and vegetables are acceptable, but grains and dairy products are not [11].

Such views have drawn criticism from anthropologists, who argue that that there is no blanket prescription of an evolutionarily appropriate diet, but rather that human eating habits are primarily learned through behavioural, social and physiological mechanisms [12]. Other commentators have noted that the claims of the Palaeolithic diet are unsupported by scientific and historical evidence [13].

So the Palaeolithic diet is probably nothing like the actual palaeolithic diet. But pragmatically speaking, is a diet sans dairy and refined carbohydrates beneficial, even if it’s not historically accurate?

Published evidence on the Palaeolithic Diet

While the proponents of the Palaeolithic diet claim that it’s evidence based, there are only a limited number of controlled clinical trials comparing the Palaeolithic diet to accepted diets such as the Diabetic diet or the Mediterranean diet.

Looking at the studies as a whole, the Palaeolithic diet was often associated with increased satiety independent of caloric or macronutrient composition. In other words, gram for gram, or calorie for calorie, the Paleo diets tended to make people fuller, and therefore tend to eat less. Of course, that may have also been because the Paleo diet was considered less palatable and more difficult to adhere to [14]. A number of studies also showed improvements in body weight, waist circumference, blood pressure and blood lipids. Some studies showed improvements in blood sugar control, and some did not.

The main draw back of clinical studies of Paleo is that the studies were short, with different designs and without enough subjects to give the studies any statistical strength. The strongest of the studies, by Mellburg et al, showed no long-term differences between the Palaeolithic diet and a control diet after two years [15].

The other thing to note is that, in the studies that measured them, there was no significant difference in inflammatory markers as a result of consuming a Palaeolithic diet. So supporters of Paleo don’t have any grounds to claim that Paleo can treat autoimmune or inflammatory diseases. No clinical study on Paleo has looked at mental illness or complex developmental disorders such as autism.

Other factors also need to be considered when thinking about Paleo. Modelling of the cost of the Palaeolithic diet suggests that it is approximately 10% more expensive than an essential diet of similar nutritional value, which may limit Paleo’s usefulness for those on a low income [16]. Calcium deficiency also remains a significant issue with the Palaeolithic diet, with the study by Osterdahl et al (2008) demonstrating a calcium intake about 50% of the recommended dietary intake [17]. Uncorrected, this could increase a patients risk of osteoporosis [18].

To Paleo or not to Paleo?

The bottom line is the Paleo diet is currently over-hyped and under-researched. There are some positive findings, but these positive findings should be tempered by the lack of power of these studies, which were limited by their small numbers, heterogeneity, and short duration.

If Paleo is to be taken seriously, larger independent trials with consistent methodology and longer duration are required to confirm the initial promise in these early studies. But for now, claims that the Palaeolithic diet could treat or prevent conditions such as autism, dementia and mental illness are not supported by clinical research.

If you’re considering going on the Palaeolithic diet, I would encourage you to talk with an accredited dietician or your GP first, and make sure that it’s right for you. Or you could just eat more vegetables and drink more water, which is probably just as healthy in the long run, but without the weight of celebrity expectations.

Comparison of the current Australian Dietary Guidelines Recommendations [19] to the Palaeolithic diet [17]

Australian Dietary Guidelines The Palaeolithic Diet
Enjoy a wide variety of nutritious foods from these five groups every day:  
Plenty of vegetables, including different types and colours, and legumes/beans Ad libitum fresh vegetables and fruits
Fruit
Grain (cereal) foods, mostly wholegrain and/or high cereal fibre varieties, such as bread, cereals, rice, pasta, noodles, polenta, couscous, oats, quinoa and barley All cereals / grain products prohibited, including maize and rice
Lean meats and poultry, fish, eggs, tofu, nuts and seeds, and legumes/beans Ad libitum lean meats and poultry, fish, eggs, tofu, nuts and seeds, but all legumes prohibited
Milk, yoghurt, cheese and/or their alternatives, mostly reduced fat (reduced fat milks are not suitable for children under 2 years) All dairy products prohibited
And drink plenty of water. Ad libitum water (mineral water allowed if tap water unavailable)

References

[1]        Duck S. Paleo diet: Health experts slam chef Pete Evans for pushing extreme views. Sunday Herald Sun. 2014 December 7.
[2]        Pitt CE. Cutting through the Paleo hype: The evidence for the Palaeolithic diet. Australian Family Physician 2016 Jan/Feb;45(1):35-38.
[3]        Konner M, Eaton SB. Paleolithic nutrition: twenty-five years later. Nutrition in clinical practice : official publication of the American Society for Parenteral and Enteral Nutrition 2010 Dec;25(6):594-602.
[4]        Eaton SB, Eaton SB, 3rd, Konner MJ. Paleolithic nutrition revisited: a twelve-year retrospective on its nature and implications. European journal of clinical nutrition 1997 Apr;51(4):207-16.
[5]        Eaton SB, Konner M. Paleolithic nutrition. A consideration of its nature and current implications. The New England journal of medicine 1985 Jan 31;312(5):283-9.
[6]        Kuipers RS, Luxwolda MF, Dijck-Brouwer DA, et al. Estimated macronutrient and fatty acid intakes from an East African Paleolithic diet. The British journal of nutrition 2010 Dec;104(11):1666-87.
[7]        Eaton SB, Konner MJ, Cordain L. Diet-dependent acid load, Paleolithic [corrected] nutrition, and evolutionary health promotion. The American journal of clinical nutrition 2010 Feb;91(2):295-7.
[8]        O’Keefe JH, Jr., Cordain L. Cardiovascular disease resulting from a diet and lifestyle at odds with our Paleolithic genome: how to become a 21st-century hunter-gatherer. Mayo Clinic proceedings 2004 Jan;79(1):101-08.
[9]        Eaton SB, Eaton SB, 3rd, Sinclair AJ, Cordain L, Mann NJ. Dietary intake of long-chain polyunsaturated fatty acids during the paleolithic. World review of nutrition and dietetics 1998;83:12-23.
[10]      Audette RV, Gilchrist T. Neanderthin : eat like a caveman to achieve a lean, strong, healthy body. 1st St. Martin’s Press ed. New York: St. Martin’s, 1999.
[11]      Lindeberg S. Paleolithic diets as a model for prevention and treatment of Western disease. American journal of human biology : the official journal of the Human Biology Council 2012 Mar-Apr;24(2):110-5.
[12]      Turner BL, Thompson AL. Beyond the Paleolithic prescription: incorporating diversity and flexibility in the study of human diet evolution. Nutrition reviews 2013 Aug;71(8):501-10.
[13]      Knight C. “Most people are simply not designed to eat pasta”: evolutionary explanations for obesity in the low-carbohydrate diet movement. Public understanding of science 2011 Sep;20(5):706-19.
[14]      Jonsson T, Granfeldt Y, Lindeberg S, Hallberg AC. Subjective satiety and other experiences of a Paleolithic diet compared to a diabetes diet in patients with type 2 diabetes. Nutrition journal 2013;12:105.
[15]      Mellberg C, Sandberg S, Ryberg M, et al. Long-term effects of a Palaeolithic-type diet in obese postmenopausal women: a 2-year randomized trial. European journal of clinical nutrition 2014 Mar;68(3):350-7.
[16]      Metzgar M, Rideout TC, Fontes-Villalba M, Kuipers RS. The feasibility of a Paleolithic diet for low-income consumers. Nutrition research 2011 Jun;31(6):444-51.
[17]      Osterdahl M, Kocturk T, Koochek A, Wandell PE. Effects of a short-term intervention with a paleolithic diet in healthy volunteers. European journal of clinical nutrition 2008 May;62(5):682-85.
[18]      Warensjo E, Byberg L, Melhus H, et al. Dietary calcium intake and risk of fracture and osteoporosis: prospective longitudinal cohort study. BMJ 2011;342:d1473.
[19]      National Health and Medical Research Council. Australian Dietary Guidelines. Canberra: National Health and Medical Research Council; 2013.

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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.

References

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

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!

References

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