Shi-Sheng Zhou et al: Vitamin paradox in obesity: Deficiency or excess?

[Richard7]

http://www.wjgnet.com/1948-9358/full/v6/i10/1158.htm

Excess vitamins have three major detrimental effects: (1) increasing ROS generation and subsequently leading to oxidative tissue damage and insulin resistance; (2) disturbing the degradation of neurotransmitters and hormones by competing for drug metabolizing enzymes and detoxification resources; and (3) causing epigenetic changes (e.g., altered DNA methylation) by depleting the body’s methyl-group pool[2,89]. Thus, fortification-induced sustained excess vitamin intake may deplete the drug-metabolizing system (e.g., manifested by high levels of unmetabolized vitamins) and the antioxidant system, and eventually cause a variety of metabolic disorders and oxidative tissue damage. This may play a causal role in the increased prevalence of obesity and related diseases, as hypothesized in our previous work[2,4,5].

The kidneys and sweat glands are the two major excretory organs responsible for the elimination of water-soluble vitamins, and the sebaceous glands excrete lipid-soluble vitamins in the sebum[17]. The excretion of vitamins is positively related to their intake. Aging is known to be associated with decreasing function of excretory organs[18,19] and thus may reduce the clearance of vitamins. It is noteworthy that sweat excretion may be particularly important in eliminating excess water-soluble vitamins, because vitamins (e.g., folate[20], nicotinic acid and nicotinamide[2,21]) are barely excreted in the urine before degradation due to the reabsorption by the renal tubules, but they can be easily excreted in the sweat[22-24].

As one of the heavier supplementers here, I have been taking some sort of B complex most days for the last 13 years or so, this caught my attention. I do not know if the biochemistry and physiology are sound but the idea is that excess vitamins have the above quoted negative consequences and that the only way to get rid of an excess of some of these vitamins is to sweat them out, which is a real problem in populations that do not sweat much.