Doubts Over Vitamin D Supplements
Vitamin D is really good for you, or so the story goes. Of course we have to have a minimum quantity of the sunshine vitamin in our systems, because we get rickets without it, but as a protection against cancer or heart disease it is not all that it is sometimes hyped up to be. There are two new reviews of all the evidence, out this week from the Annals of Medicine. There have been several hundred studies into the nature of vitamin D and these studies have pulled all this evidence together.
Vitamin D does little or nothing to strengthen bones and prevent fractures in and of itself. When taken in conjunction with extra calcium however it does seem to help prevent bone damage in older people. It would seem that the reputation of vitamin D as an efficacious compound stretches the evidence. The belief in beneficial impact on bone health is not borne out by the experimental outcomes.
To further add to our a group of medics at Boston’s Women’s Hospital are conducting a nationwide aimed at testing vitamin D and fish oil heart attack and cancer preventives.
So is vitamin D any good at all?
Much publicity has painted a picture of vitamin D as a nutritional super supplement. Apart from the aforementioned bone building powers some studies have hinted that inflated levels of D, often to be had by buying and swallowing it as a supplement can give chronic pain relief and even hold back the common cold. While other reports showing vitamin D deficiency in up to 50% of adults has done wonders for blood test sales and supplement demand. Unfortunately the science just isn’t there yet to justify any of this.
[box type="important"]The Institute of Medicine says a recommended dietary allowance (RDA) of vitamin D for all ages up to70 is 600 international units (IU), and for older folks 800 IU. The institute also say that most people already get their allowance from the sun and from foods such as fish and fortified dairy products.[/box]
[box type="note"]We all still want to believe in the curative powers of D and so the U.S. Preventive Services Task Force commissioned one of the new reviews and will update its recommendations on vitamin D for cancer and fracture prevention in early next year.[/box]
Vitamin D the Big C, and Broken Bones
Researchers at Tufts University looked again at data from more over 40 studies on vitamin D in an attempt to answer the questions about the relationship between D and cancer, D and bones, D and blood levels, and the harmful side effects if any of D.
Many studies of vitamin D plus calcium, came up with a definite maybe that taking supplements neither increased or decreased the risk of cancer. A definite no on reducing breaking bones unless it is taken with calcium.
Some studies proposed that men with higher levels of vitamin D actually had more chance of death by cancer although this was not so for women. Women did however seem in one study at least have increased risk of kidney and bladder stones. The bottom line seems to be save your money and get out in the sun more.
- Chung M, Lee J, Terasawa T, Lau J, Trikalinos TA. Vitamin D With or Without Calcium Supplementation for Prevention of Cancer and Fractures: An Updated Meta-analysis for the U.S. Preventive Services Task Force. Ann Intern Med. 2011 Dec 20;155(12):827-38. PubMed PMID: 22184690.
- McGreevy C, Williams D. New insights about vitamin d and cardiovascular disease: a narrative review. Ann Intern Med. 2011 Dec 20;155(12):820-6. PubMed PMID: 22184689.