While Dr. Mercola's response to Angelina Jolie's assertion that being a vegan nearly killed her makes some valid points...very valid points about the differences in each and every human, he clearly has his own agenda, made clear by his own words talking about vegans and the choices they make:
'While many will stay lean and avoid disease they are likely missing critical nutrients needed to optimize their health.' Staying lean and avoiding disease are important aspects of optimizing health, so which is it? You can't have your cake (vegan or not) and eat it.
A vegan diet can provide people with nearly every nutrient essential to health, with very few exceptions, like vitamin B-12 which requires supplementation. Dr. Mercola says that diligence is required to be healthy on a vegan diet. What does that mean? That we need to pay attention to what we put in our mouths? Then I agree. If more people were diligent about their eating, we would see less disease. And wouldn't that be a good thing?
And none of us know what exactly Ms. Jolie's idea of a vegan diet was. For all we know, she could have been eating lots of fruit and vegan junk food (heck, Twizzlers are vegan!). That would surely do someone in.
So before you 'abandon your previously held conviction' as Dr. Mercola advises, take a good look at your diet and see if you are eating well or just eliminating animal foods. Does your diet include whole grains, vegetables, beans, tofu, tempeh, nuts, seeds, some fruit and good quality fats? If not, you might want to re-think what you are calling a vegan diet. Ditch the junk and eat whole unprocessed seasonal foods and you will see an improvement in your health that will amaze and delight you. If you eat animal food, that is your choice, but don't let anyone tell you that it's necessary for you to be healthy.