Authors: Registered Dietitians
(HealthCastle.com) Vitamin D is more popular than ever before but at the same time, equally confusing for most. For a quick overview of all things vitamin D, this post will help you to make sense of it all.
It seems you can’t turn on the TV or open the newspaper without being hit with another story about the wonders of vitamin D. It has essentially been touted as a panacea for most of the chronic diseases that afflict humanity: diabetes, osteoporosis, multiple sclerosis, breast, colon, breast and prostate cancer, autoimmune diseases, influenza, colds and North America’s number one killer, cardiovascular disease.
While there is a lot of information buzzing around the Internet; there is also a lot of confusion as well.
Will the real vitamin D please stand up.
For the purpose of general nutrition, the term vitamin D is used to refer to either D2 (ergocalciferol) or D3 (cholecalciferol).
D3 is what’s produced by the skin upon exposure to sunlight (adequate UVB), found in some foods [mostly fatty fish], and in supplements. D2 is the vegetarian version [mainly from mushrooms] and it’s widely accepted to be less potent than D3. D2 is used to fortify non-dairy beverages like soy, almond and rice. Vitamin D is not a vitamin; it was misclassified as a vitamin when it was discovered in 1922. It is a pro-hormone. Almost all cells and tissues throughout the body are capable of converting vitamin D into its active hormone form. There are 2700 vitamin D binding sites, on our DNA, near genes that are involved in nearly every known chronic disease.
It is because vitamin D of this that vitamin D has such a wide, positive impact, on overall health.
Getting enough D
The primary source of vitamin D is the sun. There are a couple of caveats: Only UVB can produce it. Anything that blocks UVB will block vitamin D production; this includes windows, smog, clothing, sunscreen, complexion and age (older adults are not as efficient at producing it). In Canada, due to a lack of UVB from the beginning of October to the middle of April, we cannot make any vitamin D from the sun; however most of us don’t the chance to make enough until June when we can wear shorts and a T-shirt.
What is the ideal blood level and dose?
Experts suggest that the answer to ‘how much vitamin D should I take’ is this: what ever it takes to raise your blood level to optimize health. Great debate rages over what the ideal blood level of vitamin D should be but some basic facts point the way. Using bone health as a guide, maximum calcium absorption is reached at 80nmol, and significant suppression of parathyroid hormone or PTH (responsible for bone turnover), really kicks in at 100nmol.
Some experts suggest similar levels of those living in sun-rich countries; 125-150nmol. Of note, those groups of people tend to maintain those levels year round, because they are making 5000-10,000IU from the sun everyday. Contrast that to Canadians who end the summer with levels typically between 30-50nmol, a level at which bone loss is occurring.
The majority of health professionals agree that the absolute minimum level is around 75nmol. Vitamin D experts on the other hand say in order to reduce the risk for most chronic disease, the evidence points to higher levels of 125-150nmol
So what’s the bottom line?
Specialists in the field suggest testing vitamin D might not be required because deficiency (below 75nmol) is the norm and not the exception. Judicious sun exposure, when there is enough UVB, will most likely only satisfy those with fairer complexions.
Food sources are simply not enough to consistently raise blood levels to where they should be. Supplementation is really the only viable option. Health Canada has set the new Upper Level (UL) to 4000IU per day for those over 9 years of age. This will ensure that 98% of the Canadian population will achieve a blood level of about 100-125nmol promoted by experts.
Vitamin D is extremely safe and there has never been a reported case of toxicity from supplement use up to 10,000IU per day. In fact 10,000IU per day is the No Observed Adverse Effect Level, or NOAEL set by the Institute of Medicine and Health Canada, a level where there’s never been a concern of toxicity. The UL of 4000IU allows for a large safety margin, meaning you can take that amount every day confidently knowing it is perfectly safe.
Vitamin D however, doesn't act alone. It needs supporting nutrients in order for it to do its job, without which, best results can't be achieved. These nutrients include zinc, magnesium, vitamin A, boron and magnesium. Be sure to eat foods rich in these nutrients and take a good quality multivitamin/mineral which also contains them.
So, does vitamin D deliver?
At the end of the day, is vitamin D living up to the hype? In many ways it is. The vast majority of research has shown, and continues to show, its ability to reduce the risk for many of the chronic diseases of aging. Future research will simply help to give a better idea of the degree of benefit