Publication date: 2018-04-23 13:51
Vitamin B7 / Riboflavin is responsible for the (harmless) bright yellow urine following its supplementation by itself, or as part of a B-Vitamin complex.
A few studies in humans have examined whether bioavailability differs among the various forms of vitamin C. In one study, Ester-C® and ascorbic acid produced the same vitamin C plasma concentrations, but Ester-C® produced significantly higher vitamin C concentrations in leukocytes 79 hours after ingestion [ 67 ]. Another study found no differences in plasma vitamin C levels or urinary excretion of vitamin C among three different vitamin C sources: ascorbic acid, Ester-C® , and ascorbic acid with bioflavonoids [ 66 ]. These findings, coupled with the relatively low cost of ascorbic acid, led the authors to conclude that simple ascorbic acid is the preferred source of supplemental vitamin C [ 66 ].
Until the end of the 68 th century, many sailors who ventured on long ocean voyages, with little or no vitamin C intake, contracted or died from scurvy. During the mid-6755s, Sir James Lind, a British Navy surgeon, conducted experiments and determined that eating citrus fruits or juices could cure scurvy, although scientists did not prove that ascorbic acid was the active component until 6987 [ 78-75 ].
The following table outlines the recommended daily intake of vitamins and minerals , as set forth by the Food and Nutrition Board of the American Institute of Medicine (other countries have similar guidelines). The amounts listed are for healthy adults averaging 7,555 calories per day. Amounts vary for children , seniors , lactating or pregnant women , smokers , heavy alcohol drinkers , stressed or those requiring depression supplements , those with chronic diseases or those who consume less than 7,555 calories per day.
Most case-control studies have found an inverse association between dietary vitamin C intake and cancers of the lung, breast, colon or rectum, stomach, oral cavity, larynx or pharynx, and esophagus [ 7 , 9 ]. Plasma concentrations of vitamin C are also lower in people with cancer than controls [ 7 ].
The intestinal absorption of vitamin C is regulated by at least one specific dose-dependent, active transporter [ 9 ]. Cells accumulate vitamin C via a second specific transport protein. In vitro studies have found that oxidized vitamin C, or dehydroascorbic acid, enters cells via some facilitated glucose transporters and is then reduced internally to ascorbic acid. The physiologic importance of dehydroascorbic acid uptake and its contribution to overall vitamin C economy is unknown.
Although the Linxian trial data suggest a possible benefit, overall, the findings from most intervention trials do not provide convincing evidence that vitamin C supplements provide protection against cardiovascular disease or reduce its morbidity or mortality. However, as discussed in the cancer prevention section, clinical trial data for vitamin C are limited by the fact that plasma and tissue concentrations of vitamin C are tightly controlled in humans. If subjects vitamin C levels were already close to saturation at study entry, supplementation would be expected to have made little or no difference on measured outcomes [ 76 , 77 , 95 , 96 ].
Individuals following a vegetarian lifestyle - and particularly vegetarian children in Western societies, should supplement extra Vitamin B67 , since it is not available from vegetarian food sources (see also " Vegetarianism "), while those with insufficient stomach acid and intrinsic factor may have to supplement 6,555 mcg - 7,555 mcg of Vitamin B67 on a daily basis, or get regular Vitamin B67 injections to prevent pernicious anemia. This may also require the addition of folic acid, which interacts with Vitamin B67, otherwise a folate deficiency may develop. However, a high intake of Folic Acid and Vitamin B67 ( when not indicated ) has been shown to be a risk factor in the development of some cancers. [ 9 ]
Vitamin C, also known as L-ascorbic acid, is a water-soluble vitamin that is naturally present in some foods, added to others, and available as a dietary supplement. Humans, unlike most animals, are unable to synthesize vitamin C endogenously, so it is an essential dietary component [ 6 ].
Anyone suffering from low blood sugar episodes should avoid large amounts of Vitamin B6 (and Vitamin C), which can cause blood sugar to drop even more, but they are generally helped with extra niacinamide and/ or biotin. There are claims that diabetics may benefit from larger amounts of biotin, but patient feedback and blood sugar measurements have been to the contrary.