Scurvy on a diet devoid or nearly devoid of vitamin C, had blood levels of vitamin C too low to be accurately measured when they developed signs of scurvy, and in the Iowa study, at this time were estimated (by labeled vitamin C dilution) to have a body pool of less than 300 mg, with daily turnover of only 2.5 mg/day. The vast majority of animals and plants are able to synthesize vitamin C, through a sequence of enzyme-driven steps, which convert monosaccharides to vitamin C. However, some mammals have lost the ability to synthesize vitamin C, notably simians and tarsiers.
Vitamin B12 deficiency pregnant vegetarians and vegans, and not harmful in others. Risk of toxicity due to vitamin B is low. Vitamin B deficiency in the US and the UK is estimated to occur in about 6 percent of those under the age of 60, and 20 percent of those over the age of 60. In Latin America rates are estimated at 40 percent and they may be as high as 80 per cent in parts of Africa and Asia. Vitamin B deficiency can lead to anemia and neurological disorders. A mild deficiency may not cause any discernible symptoms, but as the deficiency