I think almost everybody knows that Vitamin D is what we get from the sun, and that we should give babies extra because direct sunlight is too much, or something along those lines. Here are a few extra tips and facts to explain a little more about Vitamin D, and if you should be taking supplements.
What is it, and what does it do?
Vitamin D is a vitamin that is absorbed either by food or by sunlight in it’s inactive form, and is activated in either the liver or the kidney. One of the special features of Vitamin D is that your body can make it on it’s own, by converting the energy from sunlight. This is not true of most other vitamins, that you need to consume from an outside source. It’s main function in the body to promote the absorption of calcium and phosphorus. Calcium and phosphorus are largely known for their job building bones, though they have many other important functions in the body. Calcium ions for example play a major role in muscle contraction. Sufficient amount of both of these minerals is important, and so Vitamin D is needed in order to ensure their regulation and more specifically absorption.
What if I don’t have enough?
Lack of Vitamin D, or Vitamin D deficiency can cause a lack of absorption of these compounds, which affects many parts of the body, the bones in particular. Vitamin D deficiency in children causes a disease called Rickets, and in adults it may cause osteoporosis, both of which are diseases with bone structure deficiency leading to increase chance of fractures.
However it is not just as simple as this. Vitamin D deficiency has also been linked to other diseases. The basic premise of this usually starts with the observation that certain diseases are more common further away from the equator where the sun’s rays are weaker, and is sometimes followed by more research. Claims have been made to connect Vitamin D deficiency to Colorectal cancer, Multiple Sclerosis, Type I Diabetes, heart disease and various infections including Tuberculosis.
What has been proven to help?
Although there is strong evidence to prove that Vitamin D deficiency causes a number of health problems, it’s important to review the evidence for taking supplements before jumping to conclusions. Perhaps Vitamin D deficiency is just a symptom of other conditions which cause these diseases, and supplements are a mere money making industry with little influence on the outcome, or perhaps not. So what exactly has been tested and/or proven?
First off, people over the age of 65 who take Vitamin D supplements of 700-1000 IU per day lower their risk of hip and other non-spinal fractures by 20%. The results are independent of other factors like calcium supplements, however most of the patients in the studies were also on calcium supplements so the isolate effect of Vitamin D may not stand alone.
Another study in elderly individuals found that adults who took a supplement of more than 700IU of Vitamin D had a 19% decreased risk for falls, and those who took less than this 700IU did not share the same statistical protection.
The prevalence of Rickets has also seen a dramatic fall since infants are recommended to take Vitamin D supplements, though there are still some rare cases.
Data has been collected from bone studies on incidence of cancer, and correlation has been attempted to be drawn to Vitamin D levels, however most types of cancer show weak correlation. However, a strong inverse association between Vitamin D concentrations in the blood and risk of colorectal cancer was found in a large multi-national study conducted in Europe. That being said, there has be no studies that have shown that taking supplements leads to better outcomes with respect to these diseases.
That is all in respect to the significant studies that prove efficacy of taking Vitamin D supplements. Deficiency has been shown in correlation with certain diseases, some stronger and some weaker. The clear conclusion of the Agency for Healthcare Research and Quality after reviewing more than 250 studies on the matter states that “it is still not possible to specify a relationship between vitamin D and health outcomes other than bone health.” However the efficacy of supplements has yet to be proven especially in the population that is not infants or elderly. For more information please have look at some of the references, or leave a comment if you have any other questions.
Bischoff-Ferrari HA, Willett WC, Wong JB, et al. Prevention of nonvertebral fractures with oral vitamin D and dose dependency: a meta-analysis of randomized controlled trials. Arch Intern Med. 2009; 169:551-61.
Bischoff-Ferrari HA, Dawson-Hughes B, Staehelin HB, et al. Fall prevention with supplemental and active forms of vitamin D: a meta-analysis of randomised controlled trials. BMJ. 2009; 339:b3692.
Autier P, Gandini S. Vitamin D supplementation and total mortality: a meta-analysis of randomized controlled trials. Arch Intern Med. 2007; 167:1730-7.
Newberry SJ, Chung M, Shekelle PG, Booth MS, Liu JL, Maher AR, et al. Vitamin D and calcium: a systematic review of health outcomes (update). Evidence report/technology assessment No. 217 prepared by the Southern California Evidence-based Practice Center under contract No. 290- 2012-00006-I. AHRQ Publication No. 14-E004-EF. Rockville, MD: Agency for Healthcare Research and Quality, 2014.