Are animal-based foods healthy?

It is a very common misconception that the humans need to eat animal-based food products to be healthy. It is considered conventional wisdom that animal protein is better than plant protein, that fish that we need calcium from milk to grow strong bones, or that meat is a necessary source of iron and other nutrients. As we've seen in our recent readings about lobbyist influence over government and policy makers however, this conventional wisdom may have been presented to us with ulterior motives and thus should be critically analyzed for accuracy.

Let me begin with the nutrient that according to the newest USDA issued nutrition guide, should constitute about 1/5 of our daily intake of food: Protein. Proteins are made up of "building blocks" called amino acids that our bodies cannot produce independently(1). Animal foods are often presented as containing more essential amino acids than plant foods when in reality, animals have no independent ability to create amino acids and all amino acids contained in meat is actually recycled plant protein that was consumed by the animal prior to slaughter. According to the Harvard School of Public Health(2), a 6-ounce steak contains 40 grams of protein along with 38 grams of fat. The same amount of salmon has 34 grams of protein and 18 grams of fat, while a cup of lentils contains 18 grams of protein and under 1 gram of fat. Consider these facts in conjunction with the fact that the average american consumes over double the required amount of protein, and certainly much more than double the required amount of fat (3). Some great and low fat vegetarian protein sources include quinoa, nuts, beans, tofu, and tempeh, to name a few.

Americans eat three times the global average of dairy, about 2 pounds per person each day. Just like human breast milk is the perfect blend of protein, calcium, and vitamin C for human infants, cow's milk is the perfect formula for calves, not for humans. Due to natural selection, calve's have a need to grow very quickly to minimize vulnerability in the wild, thus cow milk has enough protein to help a calf gain 2 pounds a day during the first nine months of its life (1). It is also true that human children who drink cow's milk tend to grow larger than those who don't, but clinical studies have shown that children who grow more quickly (which is not, by the way, a requirement to survive natural selection) are more likely to develop cancer later in life (1) The common belief that dairy is a requirement for strong bones is a myth bordering on a flat out lie. In fact, many studies regarding this topic point to the strange results that dairy intake may actually have inverse effects on bone health. One such study compared female dairy intake and instances of hip fractures in the United States and Hong Kong. The study found that while American females consumed nearly double the daily amount of dairy, the instances of hip fractures in American females was nearly three times that of females in Hong Kong. This research his consistent with many other studies that show that bone fractures are more common in western countries, where dairy consumption is much higher than in other parts of the world (1).

This post should not be interpreted as saying that all omnivores are unhealthy and all herbivores are healthy. Indeed, it is possible to live as a healthy animal-food consuming human just as it is possible to be an unhealthy vegetarian or vegan. This post does however, point out some of the often overlooked or intentionally ignored facts about animal-based foods that I believe everyone should be informed of when making decisions about what you put into your body. It is after all, the only body you have, so why not treat it well?

Sources
(1) D. Simon, Meatonomics. appendix A pg. 191
(2) Harvard School of Public Health, Protein. http://www.hsph.harvard.edu/nutritionsource/what-should-you-eat/protein/
(3) Physician's Committee for Responsible Medicine, The Protein Myth. http://www.pcrm.org/search/?cid=251