The Supplement everyone must take. A whopping 60% of the UK are deficient in Vitamin D.
Vitamin D is a fat-soluble vitamin and even with a balanced diet only about 10% of your vitamin D intake comes from the food.
The majority of our Vitamin D therefore comes from exposure to UV-B radiation from the sun which is absorbed by 7-dehydrocholesterol in our skin, which is converted to pre vitamin D3 which, then isomerizes into Vitamin D3.
If you live in Northern Europe or North America you are very unlikely to be getting enough sunlight for adequate D3 production. This is due to the latitude and angle of the sun not providing enough UV-B radiation.
This is even more prevalent in darker skinned individuals.
What can low Vitamin D cause?
Bone Health
Low levels of Vitamin D are a large risk factor in Osteoporosis and bone fractures.
Vitamin D helps absorb and retain Calcium and Phosphorus but with inadequate Vitamin D, bones become brittle and weak.
Lips, P., Bouillon, R., Van Schoor, N., Vanderscheuren, D., Verscheuren, S., Kuchuk, N., Milisen, K., Boonen, S. Reducing fracture risk with calcium and vitamin D. Clinical Endocrinology. 2010. 73( 3), 277–285.
Strength
Researchers have known for years that skeletal muscle is a target for Vitamin D and low levels cause muscle weakness. It influences muscle contraction which in turn reduces muscle force.
Less muscle force means you lift less which leads to less muscle mass.
Holick, M.F. Vitamin D deficiency. New England Journal of Medicine. 2007. 357(3), 266-281.
Boland, R. The role of vitamin D in skeletal muscle function. Endocrine Reviews. 1986. 7(4), 434-448.
Lean Body Mass
Vitamin D deficiency can cause muscle weakness as shown in the study above and fat inside your muscle.
Vitamin D is vital for retention of lean body mass and avoiding the formation of fat inside your muscle.
A 2010 by Kremer et al found that low levels of Vitamin D increased fat infiltration in the muscle by 24 percent compared with subjects who had adequate vitamin D levels.
Gilsanz, V., Kremer, A., Mo, A., Wren, T., Kremer, R. Vitamin D status and its relation to muscle mass and muscle fat in young women. Journal of Clinical Endocrinology and Metabolism. 2010. (95)4. 1595-1601.
Blood Sugar Regulation
Supplementing with Vitamin D has been shown to increase insulin sensitivity and decrease insulin resistance.
This shows it may be an effective way at reducing chances of type 2 diabetes.
A study in 2010 with South Asian women in a prediabetic state found that taking 4000iu a day of Vitamin D resulted in a significant increase in insulin sensitivity.
Pittas, A., Lau, J., Hu, F., Dawson-Hughes, B. The role of vitamin D and calcium in type 2 diabetes. A systematic review and meta-analysis. Journal of Clinical Endocrinology and Metabolism. 2007. 92, 2017-2029.
How much Vitamin D should we take?
Start at 2000iu of Vitamin D per day with 4000iu being the upper limit. Consider taking 4000iu if darker skinned or in winter.
The only way to know if you’re taking the right amount is by blood work.
Conclusion
60% of the UK are deficient in Vitamin D.
Vitamin D is mainly attained from the sun not food
Vitamin D deficiency increases risk of osteoporosis and bone fractures, muscle weakness, type 2 diabetes, intramuscular fat
Start by supplementing 2000iu per day, possibly up to 4000iu if darker skinned . . .
