I'm a big carnivore. But I watched "Forks over Knives" the other day - a documentary that talks about (and provides scientific research findings) eating a plant-based and whole grain diet with no meat, eggs or milk. The doctors in the documentary said that eating this way heals all sorts of diseases and gives you more energy. It sounds very appealing, but I imagine planning vegan meals will be very difficult, especially in the beginning. Any vegans out there who can attest to the health beneifts of such a diet? Do you really feel better or is this just a fad?
(If I try this, it would have to be a modified vegan diet that allows fish because life without sushi is just not worth living.)
I'm going to answer this question from what I know of diet throughout time and our physiology and anatomy. We are omnivores. We have teeth for processing both meat and vegetable material. Our microbiomes are closer to carnivores than to herbivores on the whole. Our microbiomes are also amazing things that increase our ability to extract nutrients from our diets. For example, one of the things we have learned about the microbiome is that in those who carry more weight, they often have a greater number of bacteria whose function allows greater extraction of nutrients. This would have been wonderfully adaptive in times when food was scarce, sub-optimal or during feast and famine events. In our world, where food is available in great abundance so to speak, this becomes maladaptive leading to weight issues. Couple that with lots of processed and nutritionally devoid foods, it creates an issue. People who spend a long time eating a vegan diet often loose the ability to handle meat proteins and this can lead to health issues as well. Obtaining adequate nutrition froma vegan only meal can also be difficult, not impossible but difficult. I have over the years met a few students who were vegan, staunchly and they looked incredibly unhealthy. . .anemic, bleeding gums, poor hair, etc. They were failing to obtain all that they needed for their bodies. Not all vegans mind you but some, enough as a mother to be concerning.
Prior to hunting technologies, humans scavenged meat from the kills of other animals. Once hunting technology came along meat was obtainable, but with difficulty. Anyone who hunts knows that coming back everytime one goes out with something doesn't happen, some days nothing is bagged at all. Traditionally, young men and men in their prime hunted, everyone else gathered natural resources or were involved in small time horticulture, and hunting small game. This activity provides for the majority of the caloric intake of the group. Small game (meat) and gathered plant resources including nuts. Large game is generally shared throughout and is a minor contribution overall.
Those that hunted bison on the Plains opted for females and calves, which at first seems contrary to good maintenance of the herds, but, there is such a thing as protein toxicity -- too much lean meat causes health consequences. But, females and calves have a higher fat content, which is beneficial and add to that berries, wild vegetables etc provides a well balanced diet.
Once animal domestication occurred only about ten thousand years ago, meat became a far more reliable dietary element, and a broad, vegetable diet was replaced by a few domesticated varieties mostly grains. Many groups continued to supplement with gathered vegetables.
In the Americas we have what we call The Three sisters: corn, beans and cucurbits (squashes). Despite its popularity corn is not a good nutritional source unless it is combined with beans and squashes. All three planted together provide nutrients and protection for each other. Squash speads out along the ground protecting against soil erosion and moisture retention. Beans replace nitrogens in the soil and use the corn stalks to climb. The corn proveds some shade and an anchor.
Mutualistic relationships between hunters and farmers often develop in areas where humans have diverse environments, where hunters exchange meat for agricultural products.
Those who object to a meat based diet on the basis of cruelty may be disappointed in the future as some new research indicates plant likewise have some pretty intricate sensory systems and react to things that might "hurt" them. It will be interesting to see that research develop.
So in the long and short of that, we are omnivores by physiology, anatomy and practice. I think it is too early to suggest that strict vegan diets are truly so dramatic at "fixing" health problems especially those that are autoimmune related. These are too complex for a simplistic fix. And, autoimmune things often respond initially to something but the benefits are not always maintained. Having said that in our Western world and especially in the US we eat way too much, we are decidedly meat heavy and should be consuming far more fruits and vegetables, in fact these should be probably 70-90% of our diet, add to that our propensity to over clean and have highly processed convenience foods and we are creating our own issues. Not only that but instead of working to obtain our food through hunting, gathering and farming by hand, we try to pack our hard work into an hour at the gym. So I plan on keeping meat as part of my diet along with fruits and vegetables. I would however if I weren't the black death to plants love to grow my own vegetables like my dad did when we were kiddos.