Are You Getting Too Much D?

By David Blyweiss, M.D.

Vitamin D has been in the news a lot over the past few years. And as more benefits are discovered, it seems like taking more is definitely better.

Yet not everyone seems to be on the vitamin D bandwagon. The Institute of Medicine’s Food and Nutrition Board (FNB) recently put out a report saying that taking more than 800 IU of this amazing nutrient is unnecessary and might even be harmful!

Should you ignore this report? Absolutely. So let’s look at why.

The committee only looked at the amount of vitamin D you need to build strong bones. And yes, that’s important.

But that’s only one of the many important things this beneficial nutrient does.

The health benefits of vitamin D extend to at least 100 types of disease.  And the strongest evidence is for many types of cancer (breast, colon, ovarian, pancreatic, prostate, and rectal), cardiovascular disease, type 1 and 2 diabetes, as well as respiratory infections such as the flu and pneumonia, and autoimmune diseases like multiple sclerosis.

What’s more, when you’re not getting enough D, it can affect your mood, your immune system and even your chances of dying. A 2008 study found that low levels of vitamin D increased the risk for death of any cause by a whopping 26% compared with people who had “optimal” levels of D in their blood.¹

So why isn’t your doctor telling you to take move vitamin D?

Well, most doctors look at vitamins solely in terms of what’s required to prevent a deficiency. For instance, the “recommended daily allowance” for vitamin C is the amount you need to prevent scurvy. And the recommended daily allowance for vitamin B1 (thiamine) is the amount you need to prevent beriberi.

But I think it’s important to think in terms of how much you need to support optimal health.

And the problem is, most of us just don’t get enough. And that can cost you dearly in terms of energy, health and even physical performance.

You see, scientists first noticed the connection between vitamin D and physical performance when a study was released in The Journal of Gerontology  found vitamin D helped older people with disabilities.² Another study presented at a meeting of The American Society for Mineral and Bone Research also found that low levels of vitamin D were linked to poor physical performance. In that study, older men and women with low serum levels of vitamin D performed significantly worse on standard tests for balance and strength. But after taking supplemental vitamin D, their scores improved.

These studies are just the tip of the iceberg. Here’s a quick overview of what other research suggests vitamin D can do for you:

• Regulate blood pressure.
• Play a key role in cognition later in life.³
• May help guard against age-related macular degeneration.⁴
• Help the body absorb nutrients.
• Boost immune function.
• Protect against rheumatoid arthritis.
• Reduce the severity and frequency of asthma attacks.
• Help maintain a healthy weight.⁵

So how much vitamin D should you take to get all of these benefits?

The latest recommendation of scientists on the cutting edge of vitamin D research is 2,000 IU—a far cry from the FBN’s proposal. But even that might not be enough.

Remember that the body itself will easily make 10,000 IUs after just a few hours in the sun. Based on this, I—along with some my colleagues who specialize in functional medicine—believe the correct dosage is more like 4,000 to 5,000 IU daily.

And since there’s no evidence of toxicity at this dosage, it’s the safe and effective way to get all the protection vitamin D has to offer.

1. Melamed ML. 25-hydroxyvitamin D levels and the risk of mortality in the general population. Archives of Internal Medicine. 2008;168:1629-1637.
2. Houston DK. Change in 25-hydroxyvitamin d and physical performance in older adults. The Journals of Gerontology. 2011;66:430-436.
3. Annweiler C. Association of vitamin D deficiency with cognitive impairment in older women: cross-sectional study. Neurology. 2010;74:27-32.
4. Millen AE. Vitamin D Status and Early Age-Related Macular Degeneration in Postmenopausal Women. Archives of Ophthalmology. 2011;129:481-489.
5. Shahar DR. Dairy calcium intake, serum vitamin D, and successful weight loss. American Journal of Clinical Nutrition. 2010;92:1017-1022.