here, he heard "I was vegetarian / vegan for a while, but I felt unhealthy..." so often that Jack became a registered dietitian so he could evaluate nutrition research firsthand and provide sound recommendations.
Jack makes this point in his introduction to "Staying Healthy on Plant-Based Diets":
While many people thrive on a vegan diet, others have a hard time. When someone is committed to reducing animal suffering, there are often solutions to these dilemmas, and finding answers has been a major focus of my nutrition writing. I feel that it is important to bring attention to these issues. While doing so might not initially attract as many people as claiming that a vegan diet is a health panacea, getting people to stay vegan is the more important task....
Nutritional myths have a way of going from one extreme to the other - either something is such an issue that people should not be vegan, or it is not important at all. The truth is often in the middle. Protein, calcium, and vitamin D are examples.
People once believed that in order to rely on plant proteins, you had to combine particular foods at every meal. We now know this is not true, but in countering the myth, claims have gone from "You don't need to combine proteins," to "It's easy to get enough protein on a vegan diet," to the harmful "It's impossible not to get enough protein!" On average, vegans get enough protein, but vegans who avoid legumes and soyfoods might not be getting enough and could feel unhealthy....
I would like to see vegan advocates promote the diet in such a way that we minimize the chances of someone having a bad experience. In so doing, future, long-term studies on vegans could show us to have better health than our meat-eating counterparts.
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