This argument fails on a few points:brimstoneSalad wrote: ↑Tue Nov 06, 2018 11:31 am
It's about well planned vegan diets, and that has to do with the fact that:
1. People need nutrients, not particular sources of nutrients.
2. Those nutrients are all available from non-meat sources.
3. A well planned & B12 supplemented vegan diet can contain all needed nutrients, and be modified or augmented with supplements for people who have specific problems (like those who have higher iron needs).
#1. In the abstract people just need nutrients, but we are biological systems and specific nutrients don't magically go from our month into our body. The source of the nutrients is important on a number of fronts, for example:
i.) The source of the nutrient can impact how the nutrient is absorbed
ii.) Nutrients come packaged with other other compounds and those compounds can have positive and/or negative impacts on human health.
iii.) Source can determine the form of nutrient present, for example, supplements are often made with synthetic versions of nutrients because
the natural form isn't stable outside of food. The synthetic versions typically have different metabolic pathways and as a result can have
differential health outcomes.
#2. The form of nutrients in plants and meat are often different and, as above, how the nutrients are packaged impacts how they are utilized. And while its true that all essential nutrients (other than B-12) are found in plants there is question about whether everyone can adequately synthesis the down-stream compounds from their plant-based precursors. For example, the case of synthesis rates of long-chain omega-3 fatty acids (e.g., DHA) from the short-chain versions contained in plants (ALA).
Now its certainly possible ( and I like very plausible) that with the appropriate knowledge you could craft individualized vegan diets that work for nearly everyone but we don't have that knowledge yet. Currently vegan diets are based on very general guidelines that may or may not be appropriate for most people. But many people report issues with vegan diets and there has been little done to understand the nature of those problems. There are also many people that report that they are doing well on vegan diets.