Saturday, February 2, 2013

Neal Barnard's Take

You probably know about Dr. Neal Barnard.  He is one of the leading proponents of a vegan approach to reversing diabetes and heart disease.  It doesn't hurt that he looks spectacularly healthy himself.  In this TED talk, he explains his case:

It certainly does sound appealing.  Much of Dr. Barnard's 18 minute talk essentially convinces me that humans are biologically suited to a paleolithic diet and that the industrialized food that is served all around us and which seems to fill upwards of 80% of most grocery store shelves is of no use to anybody except the pharmaceutical companies that make money off the drugs they claim will counteract the harmful effects of the poor food that is eaten.

He compares the inside of a mouth of a cat to a human mouth.  Quite clearly, we don't have teeth that are adapted to tearing into prey and ripping it apart in the same way that cats do (it does bring up the question of the logic of people who feed their cats only vegan food, though that is outside the scope of what I am writing about today).  I would tend to agree with him that we are better suited to not hunting fast moving animals in the same way as cats.

Where I disagree with Dr. Barnard, is that humans are not adapted to hunting animals at all.  He doesn't, for example, discuss the fact that humans have long been pretty adept at catching a number of other non vegan food sources.  For example, the fact that humans have historically mostly lived on or near waterways, is probably because fish and seafood have generally been an important source of protein.  Furthermore, reptiles, insects and eggs have also been a major source of sustenance to hunter-gatherers, especially those living in more land-locked areas.  In order to catch these forms of animal protein, it isn't necessary to have the attributes of a cat.

His talk discusses the role of fat, sugars and insulin at the cellular level.  I really wish he would have spent a little more time on this.  Essentially his view is that dietary fats stop insulin and glucose functioning properly at the cellular level. The low carb understanding is that sugars stop fats and insulin functioning properly at the cellular level.  Both views agree that this malfunctioning causes plaque build-up in the arteries.  My understanding of biological science is very limited, so I really am not in a position to comment on which explanation is more scientifically valid.  It is worth pointing out that Dr. Barnard is not a nutritional scientist either, which might explain why he spent relatively little time explaining his theory.  It would be helpful to non-experts like me, to find a real expert to weigh in on the facts.

Turning to more practical matters, Dr. Barnard talks about a 2006 study that he led, which studied 99 people with diabetes who were put on a 22 week vegan diet, with 50 control subjects who were assigned a standard diabetic diet.
RESULTS—Forty-three percent (21 of 49) of the vegan group and 26% (13 of 50) of the ADA group participants reduced diabetes medications. Including all participants, HbA1c (A1C) decreased 0.96 percentage points in the vegan group and 0.56 points in the ADA group (P = 0.089). Excluding those who changed medications, A1C fell 1.23 points in the vegan group compared with 0.38 points in the ADA group (P = 0.01). Body weight decreased 6.5 kg in the vegan group and 3.1 kg in the ADA group (P < 0.001). Body weight change correlated with A1C change (r = 0.51, n = 57, P < 0.0001). Among those who did not change lipid-lowering medications, LDL cholesterol fell 21.2% in the vegan group and 10.7% in the ADA group (P = 0.02). After adjustment for baseline values, urinary albumin reductions were greater in the vegan group (15.9 mg/24h) than in the ADA group (10.9 mg/24 h) (P = 0.013).
Tucked away at the end of the body of the study, are the only references to HDL and total cholesterol:
Changes in HDL cholesterol were −0.16 mmol/l (−6.0 mg/dl, −11.0%) for the vegan group and −0.07 mmol/l (−2.8 mg/dl, −5.7%) for the ADA group (P = 0.14). The total-to-HDL cholesterol ratio fell for both groups, as did triglyceride concentrations. 

It is unfortunate that the control group in this study followed a standard diabetic diet.  It would have been much more helpful if a third group of test subjects had followed a low carbohydrate, high fat diet.  Then we could have discovered more objectively which approach is better.

While the results definitely do show statistically valid improvements in the vegan group, it bears pointing out that Dr. Barnard's study focuses more on LDL than HDL.  As I have mentioned before in this blog, an LDL count is not only likely to be inaccurate, but it also isn't really predictive of anything much at all.   

My major concern against purely plant-based diets lies in the fact that dietary fats contain a wealth of  nutritional benefits that are not commonly talked about by the people who push them.  They often conveniently (perhaps unknowingly) claim that their plant-based diet provides them with all the nutrients they need, while this might not be strictly true for long term health.

For example, vitamin K2 is fairly easily obtained by eating liver and egg yolks, and helps the body to ensure dietary calcium ends up in the bones instead of lining the arteries as plaque.  Nothing major will happen to you in the short term if you don't get enough vitamin K2, so any deficiency is likely to go unnoticed.   The only known vegan source of vitamin K2, natto, happens to be an excellent one but it is relatively obscure outside Japan.  I would be interested to know how many people who find purely plant-based eating compelling are sufficiently committed to it to either make their own, or import, these foul smelling fermented soybeans. 

Perhaps hard-core vegans like Dr. Barnard eat natto regularly, but I have seldom seen vitamin K mentioned in a popular vegetarian publication, other than in the context of the other vitamin K that comes from the chlorophyll in green leafy vegetables.  For more reading on vitamin K (and the differences between the two kinds), I recommend Kate Rheaume-Bleue's excellent book Vitamin K2 and the Cacium Paradox: How a little-known vitamin could save your life.

Another food I have been researching quite intensively lately is bone broth.  Again, something that is not available to those on a plant based diet, the theory is that regular infusions of the micronutrients and proteins inside slow cooked animal bones are essential to long term human health.   A teaser for a future post I'll be writing soon:  we have been experimenting with regular broths in our house in the last couple of months.   Curious about Ray Peat's conviction that gelatin aids sleep, I have been on a chicken foot quest that ended at one of our local Asian stores yesterday.  After a half-cup of rich chicken foot broth last night, I didn't wake up until 7.30 am this morning, something that hasn't happened in months.  Coincidence?  I don't know, but suffice it to say at this point that chicken foot broth is not available to Dr. Barnard's vegan followers.

I do find it heartening that Dr Barnard talks about our paleolithic ancestors, and I firmly believe that any diet that rejects industrialized food is a great step forward.  While he might be horrified to hear me say it, I do think there are some major commonalities between his approach and the meat-based paleolithic one.   There are not enough commonalities to convince me that a purely plant-based diet is the right one for me, but it seems to work for him and many of his patients. What I am convinced about is that we have a lot more to learn about the food we need to maintain optimum health and longevity, and I will continue to explore this fascinating subject while keeping my skeptical mind as open as I can.

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