Regarding veganism, in comparing anecdotes and personal experiences of happy and healthy vegans to the general population, there are several points that ought to be considered.
First, the general population is a poor comparison group. This group is eating a daily concoction of slow poisons, in particular, all manner of sugars, processed grains, and industrial seed oils, each of which is terrible even on its own, and far worse in a self-reinforcing cocktail of all three.
An implication of this comparison group issue is that even if X seems far better than Y, this does not necessarily tell us that X is optimal.
When Y (the general population’s diet) is really, really bad (as it is), there should be quite a number of ways to improve on that. Another trouble with anecdotes is fairly wide individual variation in tolerance for various conditions and foods.
Second, in this light, it is important to note that going vegan is often combined with getting off of a conventional diet.
This also usually entails reducing or eliminating most processed foods and adopting whole foods. It is often also found together with above-average awareness of other (non-dietary) health issues and practices (sleep, activity, stress, abstention from harmful recreational substances). These factors are in themselves already hugely beneficial. And whatever the whole foods are that are adopted, they are likely to be better than whatever processed foods are abandoned. The real confusion is that this is so regardless of plant versus animal source (dairy is more complex I think). For example, many of the negative meat study results (besides the serious design problems with most of the popular epidemiological studies in general) come from chemically preserved, rather than fresh, meats. Such factors conspire to heavily confound interpretations of what, exactly, it is that has caused noted positive or negative effects. The cessation of previous negative effects, for example, is often caused mainly by the successful elimination of harmful items.
Third, my reading on the health effects of veganism indicates that many of the negative issues appear longer-term only after a process of gradual degeneration. Homo sapiens are able to live only on plants, but my understanding is that in evolutionary terms, this is primarily a residual ability useful as a fall-back for bad hunting periods. Our digestive systems are not built for relying on plants, unlike, say, those of gorillas, who eat only plants, and whose digestive systems are accordingly completely unlike ours in the amount of space and energy dedicated to various digestive organs. For example, a massive gorilla digestive organ that serves as a plant fermentation tank corresponds to our tiny vestigial appendix, according to Barry Graves. One good critical chapter on the long-term health effects of veganism is Chapter 4 of The Paleo Solution by Loren Cordain.
The Big Fat Surprise, written by the person the above story link was about, also has up to date analysis of the health effects of various food categories and fat types, etc. There has been a great deal of very poor information pushed in this field over the past decades, which has happened to correlate with 1) the making of a great deal of money from “food” products and pharmaceutical products (many of which treat chronic effects of those same “food” products) and 2) an unprecedented and rapidly worsening health crisis. Nina Teicholz’s book goes a long way toward clarifying where some of that ubiquitous misinformation has come from and replacing it with something better grounded in research.
— Konrad Graf, http://www.konradsgraf.com/blog1/2017/7 ... tal-health