To meat or not to meat?

Both Kevin and Blair are people who take an active role in knowing about and deciding what they put on their plate, together they have researched their diets and have written on the health, sustainability, and ethical aspects of meat based and meatless diets. This week’s post is concerned with the health implications of including/excluding meat from your diet. So take five minutes between studies and feed your mind with something a bit more interesting than your statistics 101 assignment.

Question: Is inclusion/exclusion of meat healthy?

Kevin’s response (the Vegan/vegetarian/awesome)

To begin with, lets just put it out there, being a vegetarian or vegan isn’t unhealthy. But much literature and popular thought in the past has been contrary to this statement.

According to Messina, Mangels, and Messina (2004), the dominance of government sponsored nutritional guidelines has promoted meat based diets over vegetarian diets without sound nutritional justification. Marion Nestle (2006) explains in her books the problematic nature of organisations such as the USDA who regularly release and update nutritional guidelines in the USA, this being secondary to their main goal of promoting sales of American food commodities. Anyone who thinks this is an American problem, try visiting the websites for New Zealand beef and lamb or the New Zealand seafood industry. The links below will take you to Iron Bryon (a mascot directed toward children to promote ‘New Zealand’ beef and lamb) and a guide for pregnant women, which promotes seafood consumption despite doctor’s recommendations to restrict eating seafood due to concerns of methyl mercury and neural tube defects.

BUT! There are some legitimate concerns for the health of those that restrict their intake of animal products, especially for vegans. In a paper by Sanders (1988) the two issues of Bulk and B12 were addressed. Bulk is a problem faced by those that eat more fruits and vegetables, whilst avoiding energy dense animal products. This means that overall they may often not meet their daily energy requirements. Whilst this is beneficial for many adults today who consume energy in excess, for children and pregnant women who have increased energy requirements it can be problematic.

According to M., M. and M. (2004), vitamin B12 is synthesised by bacteria, fungi and algae. It is present in animal products because animals ingest micro-organisms producing/containing B12. Most B12 is lost through the excretion of bile in the intestines, but because the body is so good at reabsorbing it, generally B12 deficiency isn’t an immediate problem for vegans unless they cannot reabsorb it. Whilst vegans generally won’t have levels of B12 as high and omnivores, this is not a problem. Many vegans can receive B12 from partially washed vegetables, uncooked nori, or through dietary supplements.

But these are not problems for the many people that still eat dairy and eggs, and overall Vegetarian/vegan diets are more than adequate when it comes to all other micronutrients. Concerns do exist for the bio-availability of Zinc and Iron from plant foods, but this can be solved with smart eating. Vitamin D can also be a concern for Vegans who don’t get enough sun, but fortunately many common vegan foods are fortified with vitamin D.

Moving on, are there any health benefits to excluding meat from your diet? M., M. and M. (2004) and Nestle (2006) both state that Vegetarians tend to be healthier and suffer lower rates of lifestyle diseases that plague developed countries, but there can be confusion about how much of this is artefact since many vegans tend to also live healthier lives in general.

But this isn’t all of the truth. To put it in general sweeping yet referenced statements, Vegetarians/Vegans consume less saturated fats, cholesterol and protein than non-vegetarians. Vegetarians/Vegans do consume more polyunsaturated fats, complex carbohydrates, fibre, beta-carotene, and vitamins C and E (M., M., and M., 2004). M., M., and M. also state that vegetarians have lower rates of cancer, heart disease, hypertension, diabetes, gallstones, kidney disease, and colon disease. Other evidence has also indicated reduced risk of rheumatoid arthritis, gout, dementia, constipation, tooth decay, and duodenal ulcers.

To conclude, let’s just remember that vegetarian/vegan diets aren’t nutritionally radical. The pitfalls that have been mentioned are only found among the most careless vegan diets and so for many practicing vegetarians/vegans they aren’t problems at all. Some people have come to me saying that their special dietary requirements cannot allow them to stop eating meat. But, for the most part, investigation and dietary planning can be used effectively to ensure adequate nutrition for those with nutritional disorders and for those with increased nutritional needs.

I’ll finish with a quote by M., M. and M. (2004):

“It is clear that vegetarian eating patterns adhere more closely (than omnivorous) to guidelines for optimal diet and are similar to diets of populations with reduced chronic disease risk.” (Page. 45).

 References and Links:

Messina, V., Mangels, R., and Messina, M. (2004). The Dietician’s Guide to Vegetarian Diets: Issues and Applications (2^nd ed.). Jones and Bartlett Publishers: Boston.

Nestle, M. (2006). What to Eat. North Point Press: New York.

Sanders, T. (1988). Growth and development of British vegan children. In American Journal of Cinical Nutrition, 48. 822-5.

Link to Iron Bryon: http://www.beeflambnz.co.nz/index.pl?page=kids&m=73

Link to seafood and pregnancy: http://www.greatestmeal.co.nz/seafoodandpregnancy

Blair’s response (Pro meat/Paleo/Primal)

To be clear from the beginning when I talk about a meat based diet, I do not mean a diet of only meat, like the Inuit (not that their diet is unhealthy). What I mean is a diet with an average of one serving of animal protein per meal, that what I try for daily, and that is what I will from here on call a ‘meat based diet’.

When we think about what makes up a healthy diet, we cannot just look at the conditions we find ourselves in today; we must look back though evolution to see the diet which we have evolved to eat. Anthropologists looking at modern hunter gatherers (whose diets should closely reflect those of the past) found that they eat between 45 and 65 percent of their energy requirements as animal products. This increase in dietary fat (and cooking) 2 million years ago is what could have allowed us to grow our large brains. It is well known that meat is an excellent (the best?) source of protein in the diet. Humans can also obtain all their necessary vitamins and minerals from meat (the Inuit have done so for thousands of years). Use any online calculator and compare the nutrient density of liver with that of fruit and for half a cup of liver; you would have to eat 2 kilos of some fruit to reach the same level of nutrients.

So, what if we didn’t eat meat? We can look into the diet of vegetarians and find nutrient deficiencies, such as B12 deficiency requiring supplementation. The diet of vegetarians is often low in protein, and the protein they do receive comes from poor sources such as legumes (containing phytates which remove nutrients), grains (containing gluten) and soy (containing isoflavones, which effect hormones). It is a difficult and inefficient to be healthy without meat.

Despite how obviously good meat is for us, we find ourselves constantly bombarded with messages of how meat is bad for us. It’s full of toxins; it will give you cancer or heart disease etc. Let’s start with liver since it has been mentioned.

“Isn’t liver full of toxins, it’s the bodies filter for those things isn’t it?” Well, no it isn’t. A more correct metaphor would be that it is the body’s chemical processing plant. The liver processes toxins to make then inert, then removes them from the body (usually via the kidneys i.e. in the urine), it doesn’t hold onto the toxins. A study in 2004 compared levels of Arsenic, cadmium, copper, lead, mercury and zinc in beef organs and muscles. The results showed similar levels (all very low) in all tissues, not a build-up in the liver.

Since Ancel Keys in the 50’s everyone has had the erroneous belief that dietary fat along with cholesterol, and in particular saturated fat, makes us fat and give us heart disease. While there is not time to go depth on this issue here (for further reading see Good calories, bad calories by Gary Taubes), what can be said is that the Framingham heart study one of the longest-running, most comprehensive and most highly cited observational studies analysed the relationship between saturated fat intake, serum cholesterol and heart attack risk and found no significant relationship between saturated fat intake and blood cholesterol or heart attack risk, or total mortality.

Referencing:

1. Plant-animal subsistence ratios and macronutrient energy estimations in worldwide hunter-gatherer diets, Loren Cordain, Janette Brand Miller, S Boyd Eaton, Neil Mann, Susanne HA Holt and John D Speth, American Journal of Clinical Nutrition, Vol. 71, No. 3, 682-692, March 2000
2. The American Association for the Advancement of Science, Science and Technology – What’s cooking?The evolutionary role of cookery, Feb 19th 2009. (Also see- Catching fire: How cooking made us human.)
3. Distribution of Some Trace and Macrominerals in Beef, Mutton and Poultry, Irfana Mariam, Shehlav Iqbal and Saeed Ahmadnagra, International journal of agriculture and biology, 1560–8530/2004/06–5–816–820
4. Good calories, bad calories, Gary Taubes, 2008

Congratulations to everyone who finished. Our next post will be Monday the 30^th of May and will address sustainability concerns with our food choices.

Feel free to leave comments or troll the comments section since both Blair and Kevin will be providing answers to most (or some) criticism in the final two posts on the 13^th and 20^th of June.