Back in the days, Arnold and Franco would be seen tanning on the beaches in Venice. Today bodybuilders rely on Pro-Tan and artificial methods of tanning and therefore may be be missing out on Vitamin D. Vitamin D deficiency is a global health problem. Over one billion people around the world are deficient in vitamin D. Vitamin D, or the the Sun Vitamin is a steroid with hormone like activity which regulates the functions of over 200 genes and is considered to be essential for development and growth.
In humans the two important forms of Vitamin D are Vitamin D3 or cholecalciferol and Vitamin D2 or ergocalciferol. Vitamin D levels depend on the intake of Vitamin D through the diet or by dietary supplements as well as on the production of vitamin D3 in the skin by UV radiation from the sun. Around 50% – 90% of vitamin D is produced by exposure of skin to the sun and the remaining from the diet.
Important dietary sources of vitamin D include fortified dairy products, beef liver, fatty fish and egg yolk. Vitamin D deficiency has been linked to various health conditions including atherosclerosis in addition to vitamin D’s role in calcium and bone metabolism. Vitamin D is also important in the functioning of the endothelial cells lining blood vessels and without sufficient vitamin D, the endothelial cells become susceptible to dysfunction and damage leading to arterial calcification and atherosclerosis.
Vitamin D and Building Muscle
Vitamin D is actually a pro-hormone produced in the skin and unlike other vitamins, Vitamin D has a hormone receptor VDR. VDRs are found in at least 36 different organs in the body. To check if Vitamin D3 has an anabolic effect, researchers carried out an in-vitro (out of the body) study with the use of muscle cells, leucine, insulin and Vitamin D. The focus of this study was the mammalian target of rapamycin (mTOR) anabolic signalling pathway in muscle cells. Leucine activates the mTOR pathway directly and high levels of insulin promotes the activation of the pathway. Leucine being a direct activator of the mTOR pathway can switch on protein synthesis within muscle cells. The researchers exposed muscle cells to insulin and, or insulin, Vitamin D and leucine. The results of their study showed that the addition of Vitamin D to leucine and insulin greatly enhanced mTOR pathway activity as well as protein synthesis in the muscle cell. In conclusion, it was established that Vitamin D directly alters protein synthesis within muscle cells.
More to say, studies have also found that low levels of vitamin D is associated with low testosterone levels. A study found that men with adequate levels of vitamin D have higher testosterone levels and lower SHBG, compared to men with insufficient Vitamin D levels. Yet another study done came to find that male participants who took 3332 IU’s of vitamin D per day for a year, had an average of 25.2% higher testosterone levels as compared to the placebo. Thus getting outside and under the sun may be anabolic for bodybuilders!