Vitamin D is found in many dietary sources, such as fish, eggs, fortified milk, and cod liver oil. The sun also contributes significantly to the body’s daily production of vitamin D—in fact, as little as 10 minutes of exposure a day is thought to be enough to prevent deficiencies.
The term “vitamin D” refers to several different forms of this vitamin. Two are important in humans: ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3). Plants synthesize vitamin D2; humans synthesize vitamin D3 in the skin when it’s exposed to sunlight’s ultraviolet B (UVB) rays. Foods may be fortified with vitamin D2 or D3.
Vitamin D has been found to play a substantial role in muscle growth, but new research suggests this may actually be related to its anabolic activity with leucine. Researchers who exposed muscle cells in test tubes to leucine, insulin, and varying concentrations of vitamin D3 found the more D3 in the test tubes, the greater the anabolic effect. Higher concentrations of D3 were also linked to the greater anabolic signal proteins such as Akt, GSK3, p70-S6K, and 4EBP1.
So make sure you’re getting adequate amounts of vitamin D in your diet, or exposing yourself to adequate levels of sunlight. - FLEX