Vitamin D Nicknamed the sunshine vitamin, vitamin D is produced by your skin when it's exposed to sunlight.
The results were deemed to be inconsistent with several of the previously published observational studies, based on which the trial had been designed to reduce the risk of lung cancer.
However, this trial was conducted in an area where micronutrient intake was quite poor, and thus supplements might have had a beneficial role. Summary: Dietary vitamin D can be classified as vitamin D2, found in mushrooms and plants, and vitamin D3, found in animal-derived foods.
The answer is perhaps multifactorial. Studies suggest that vitamin A acts by suppressing the measles virus A diet rich in omega-3s—found in fatty fish, like salmon, tuna and mackerel, as well as in walnuts, flaxseed and canola oil—and low in saturated fats may help protect against heart disease, stroke, cancer and inflammatory bowel disease.
Most notably, Linus Pauling, a two-time Nobel Laureate and a towering figure in chemistry, believed that vitamin C could prevent cancer and increase the life expectancy of cancer patients.
The most abundant dietary sources of vitamin A are liver, fish liver oil and butter. Vitamin D3 is more efficiently converted into calcitriol than vitamin D2.
Nevertheless, while getting enough vitamin A is vital, too much may cause harm.