Vitamin D is a nutrient (well, technically a hormone) that has had a substantial amount of research devoted to it over recent years. As someone who enjoys keeping up with the latest findings, I am often dismayed at the outdated — and often inaccurate– information shared with the public.
Below, three crucial, but little-known, vitamin D facts everyone must know for the sake of their health.
1. Current Vitamin D Recommendations Are Too Low
When I suggest to a client that they supplement 4,000 to 6,000 International Units (IUs) of vitamin D a day, their first reaction is usually one of two: “But I already take a multivitamin” or “Wow! That sounds like a lot”.
It does sound extreme when you consider that the current recommended daily intake is set at 600 IUs for anyone between the ages of 14 and 70 (this was increased a little over a year ago from the former recommendation of 400 IUs). Your average multivitamin provides anywhere from 400 to 600 IUs.
The problem is that the 600 IUs recommendation is based on research that solely examined vitamin D’s role in bone health. While that is certainly one function of vitamin D, there are many more (almost every cell in the human body has vitamin D receptors). Newer research has implicated D in blood glucose control, mood disorders, and heart health.
Besides, when we make vitamin D from the sun, we can make up to 10,000 International Units a day under optimal conditions (certainly calls into question some recommendations which set an Upper Tolerable Limit of 2,000 IUs). And, while anecdotal, the only way I have seen deficiencies corrected — in both clinical and outpatient settings — was with supplementation of anywhere from 4,000 to 10,000 International Units a day (depending on the severity of the deficiency).
2) You Don’t Make Vitamin D From the Sun Year-Round
Many individuals who learn they are vitamin D deficient are often surprised since “they are always out in the sun”. Depending where you live, though, your ability to make vitamin D is inhibited for many months.
There isn’t full agreement in the health field, but the most common belief is that if you live north of the 35th parallel (see map here), your body is unable to make vitamin D from the sun for several months (roughly from November to April). For what it’s worth, some people abide by the “33rd parallel” theory, while others think “the 37th parallel” is more accurate.
The point is — if you’re north of Los Angeles, you are not making vitamin D for many months, even if you are out in the sun, at noon, wearing next to nothing. The reason? The sun’s UVB rays — the ones responsible for vitamin D production — don’t reach you.
3) There Are A Lot of Barriers to Vitamin D Production
Let’s say you live in an area where you can make vitamin D year-round. Or that you’re all the way up in Boston, but it’s the middle of July, so the UVB rays are on and poppin’. You are getting all your vitamin D from the sun, right? Not quite. There are many barriers that can inhibit vitamin D production:
- Air pollution.
- Sunscreen. “Sunscreens with SPF ≥ 15 almost completely inhibit vitamin D3 production”. Keep in mind that most commercial moisturizers contain SPFs in the 20s, 30s, and 40s.
- Time of day. The general rule is that if your shadow is longer than your body, the sun’s rays are not high enough to produce vitamin D.
In summary: 600 IUs of vitamin D a day won’t cut it. You owe it to yourself to have proper levels, and, to do so, you can’t depend on sunlight or the paltry amounts fortified in food.
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Sign in nowNice tidy, clear article about Vitamin D realities. Definitely in line with my other readings about recent vitamin D findings. makes me feel better about my D intake (>1000, <2000) as not being too high, , but makes me consider higher levels especially in winter. Since I'm in Canada, I don't worry about 34th or 37th… Both WAY south of me.
Good article, but can you change the “we make 10000 IUs” statement to something like “we CAN make UP TO 10000 IUs” or “STORE UP TO” or something similar. Its a little misleading and made me do a triple take and read the paper, which says full body exposure to UV rays for X amount of time (that I didn’t see). I don’t go run outside naked, or go to tanning booths.
Thanks.
Brandon,
It’s not about running outside naked. It can mean something as simple as sunbathing for 30 – 60 minutes during optimal exposure times. I’ll reword that sentence so it is more clear.
I have always been a bit conflicted about supplements. It seems more logical to me that eating a diet consisting of a variety of whole foods should provide all the nutrition that we need. Otherwise, how did the species survive for so long before the invention of supplements?
Shereen,
Vitamin D is not plentiful in the food supply. The popular vitamin D beverage — milk — only contains it because of fortification (it does not occur naturally).
As for the survival of our species: low levels of vitamin D do not cause death. They increase the risk of certain diseases and can speed up/worsen conditions like osteoporosis, but most people you know today spend decades living with some degree of vitamin D deficiency or insufficiency.
Also, certain factors that inhibit vitamin D production, like air pollution and SPF, were not an issue hundreds of years ago.
For some reason I can’t seem to find vitamin D supplements without Calcium in them.. Since it appears that Ca supplements are potentially problematic, I’d like to avoid taking it.
Felix,
That’s interesting; I assume you don’t live in the US (not only based on your comment, but also on your e-mail address)? There are no stores that sell plain vitamin D?
Other than vitamin D, is there anything specifically you think most people should supplement?
I recommend B12 supplements to vegetarians and vegans. I also think most people should supplement probiotics (unless they eat fermented foods regularly, which I don’t find to be very common) and DHA and EPA Omega 3s.
Is there a major difference between supplementing with Vitamin D2 vs. D3?
Hey Andy, in the stores I frequent, no. It’s always together with either Ca or Ca+Mg. I discovered that I can order plain Vitamin D from Amazon though..
How many IU/day would you recommend for children?
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