Vit. B12 and aging
Vitamin B12 Deficiency Can Cause Symptoms That Mimic Aging. "Natural plant sources are meager at best in B12, and the vitamin is poorly absorbed from them. Many strict vegetarians and all vegans, as well as infants they breast-feed, must consume supplements or fortified breakfast cereals to get adequate amounts."
A severe B12 deficiency results in anemia, which can be picked up by an ordinary blood test. But the less dramatic symptoms of a B12 deficiency may include muscle weakness, fatigue, shakiness, unsteady gait, incontinence, low blood pressure, depression and other mood disorders, and cognitive problems like poor memory.
For more info. please check the New York Times, health section, Nov. 28
article on Vit. B12 and aging by Jane Brody. Sorry, as a comouter idiot,
my computer won't allow me to post the link to article here.
Also note that baterium Spirulina contain psudo-B12 that our body can't utilize, so it's actually bad for vegetarians.
聽說印度因食物常黏土禳故 B12 deficiency 罕見，
I read this article when I was in NYC and had exactly the same discussion with a few vegan friends over FB. In the US, you can easily find soy and almond milk that are B12 fortified. I checked, for instance, if you drink about 400CC soy milk, you get your daily recommendation of B12. It would be interesting to know if Taiwanese vegan industry also adds V12 in their vegan products.
Though theoretically, if you are a pure vegan, you literally do not have natural source of B12 from vegan food(unless you intake a small amount of soil that come with food, like from vegetables or potato skin etc since there are B12 in soil), and we would have thought that there would be a lot of monks, Buddhists who show some B12 deficiency problems. However, I do not recall to have seen that there is a B12 deficiency "endemic" in these religious vegan groups. I do not know why since we should have seen this since there wasn't B12 fortified food or supplements available till more recently.