Vegetarians and omnivores have similar levels of serum iron, but levels of ferritin—the long-term storage form of iron—are lower in vegetarians than in omnivores.
https://www.ncbi.nlm.nih.gov/pubmed/24871479

Fruits and Vegetables
https://www.ncbi.nlm.nih.gov/pubmed/12064344

This is significant, because ferritin depletion is the first stage of iron deficiency. Moreover, although vegetarians often have similar iron intakes to omnivores on paper, it is more common for vegetarians (and particularly vegans) to be iron deficient. For example, this study of 75 vegan women in Germany found that 40% of them were iron deficient, despite average iron intakes that were above the recommended daily allowance.
https://www.ncbi.nlm.nih.gov/pubmed/14988640
http://ajcn.nutrition.org/content/78/3/633S.long

many plant foods that contain zinc also contain phytate, which inhibits zinc absorption. Vegetarian diets tend to reduce zinc absorption by about 35% compared with omniovorous diet.
http://ajcn.nutrition.org/content/78/3/633S.long

Thus, even when the diet meets or exceeds the RDA for zinc, deficiency may still occur. One study suggested that vegetarians may require up to 50% more zinc than omnivores for this reason.
http://ajcn.nutrition.org/content/78/3/633S.long

The Naive Vegetarian
http://www.second-opinions.co.uk/vegetarian.html#.WTTqMNwlEqT

Onions decreases your testosterone
https://www.ncbi.nlm.nih.gov/pubmed/15735098
https://www.ncbi.nlm.nih.gov/labs/articles/10798211/

Why you need dietary cholesterol:

Very great total picture kind of lecture:
https://www.youtube.com/watch?v=uc1XsO3mxX8

>>715108986
No, their influence isn't the same. While cattle are versatile, they don't power the entire economy like energy does. Governments can build infrastructure.