eating · health

Vitamin D: What’s a reasonable person to do?


I often blog about topics where I’ve done some research and thought I’d save you the time. On topics such as exercise non-responders (Or, are you a non responder?), intermittent fasting and women’s health (Intermittent fasting and why it might not work), and athletes and pain tolerance (Are athletes masochists?) I’m far from an expert in the field but I’ve read enough to have some conclusions to share.

But on some topics, I’m perplexed. I’ve read a fair bit but I’m still not sure what to think or do about Vitamin D.  Let’s start with the question that many of us in the northern hemisphere worry about, are you getting enough Vitamin D?

Some reports suggest nearly half the world’s population suffers from vitamin D deficiency, which is unsettling news given that a lack of vitamin D has been associated with a host of serious conditions: cancer, heart disease, diabetes, multiple sclerosis, tuberculosis and even depression, not to mention brittle bones and the common cold.

But it’s not clear that supplements help. See the Limits of Vitamin D Supplements.

A large review of studies has found that vitamin D supplements have little or no benefit beyond the low levels required for bone health.

The meta-analysis, published in The Lancet Diabetes & Endocrinology, combined data from 290 observational studies and 172 random trials. All the studies used blood levels of vitamin D to measure outcomes. Dosages varied, but most trials used 800 units or more.

The observational studies generally found an association of lower vitamin D levels with increases in cardiovascular disease, lipid concentrations, glucose levels, weight gain, infectious disease and mood disorders. But random trials showed little or no effect of vitamin D supplements on any of these problems. The authors conclude that low vitamin D levels are almost surely an effect of these diseases, and not a cause.

Current guidelines recommend supplements for anyone with a blood level under 30 nanograms per milliliter, but the lead author, Dr. Philippe Autier, said that only at levels of 10 or less would there be a risk to skeletal health. Less than 10 percent of Americans, he estimates, fall into this category. Dr. Autier is a researcher at the International Prevention Research Institute in Lyon, France.

“Unfortunately, there is probably no benefit to expect from vitamin D supplementation in normally healthy people,” he said.

See also, from Precision Nutrition, Vitamin D supplements: Are yours helping or hurting you?

Almost every expert recommends it. And everyone’s taking it. But what if we’ve been using it wrong? What if our vitamin D supplements aren’t really helping us at all?
If your car’s oil light went on once a week…and every time you checked the oil, it was running low…what would you do?
Shrug? Top up the oil tank (again)? Do your best to forget about it?
Or would you try to figure out the cause? Why that oil light kept coming on? Why your oil was running low?
If you’re smart, you take your car to the mechanic. Where you learn that low oil is just a symptom. There, the mechanic looks for the real problem.
Why, then, don’t we take the same approach with our health? With our supplements?
Why’s that vitamin D low?
Research over the last few years has indicated that a large percent of the world’s population is low in vitamin D. However, the response to this is kinda strange.
Healthcare practitioners typically test a patient’s vitamin D levels and notice that they’re low.
Then s/he prescribes a vitamin D supplement.
The patient comes in again a few months later and vitamin D is still low.
So the doctor increases the supplement.
Interestingly, very few professionals ever ask: Why is this person’s “vitamin D tank” leaking in the first place?

In case you thought indoor tanning in the winter was a reasonable response, think again. The Canadian Cancer Society says, “Using tanning beds may increase vitamin D production, depending on the type of bulbs used (only UVB radiation can stimulate vitamin D production). But tanning beds are not a safe way to get vitamin D. There are safer ways to get vitamin D.”  Read more:

The International Skin Cancer Foundation puts in in stronger terms.

No … no… no! A tanning bed will never provide you with the vitamin D that you need, nor is it safer than tanning outdoors. Not understanding the facts can literally mean the difference between life and death. Both ultraviolet A (UVA) and ultraviolet B (UVB) radiation cause cell damage that can lead to skin cancer. When you lie in an indoor tanning bed, you are exposed primarily to UVA, which penetrates deep into the surface of the skin, damaging the cells beneath and prematurely aging your skin. But it is UVB (the sun burning rays) — not UVA — which helps the skin make vitamin D, so you are increasing your risk of skin cancer without receiving any benefit!

As for the claim that tanning beds emit a controlled dose of UV radiation, a “controlled dose” of UV radiation from a tanning bed is a dangerous dose: frequent tanners using high-pressure sunlamps may receive as much as 12 times the annual UVA dose compared to the dose they receive from sun exposure.

It’s estimated that 10 minutes in a tanning bed matches the cancer-causing effects of 10 minutes in the Mediterranean summer sun. This may be one reason that indoor tanners are 74 percent more likely to develop melanoma, the deadliest form of skin cancer, than those who have never tanned indoors, and that people who use tanning beds are 2.5 times more likely to develop squamous cell carcinoma and 1.5 times more likely to develop basal cell carcinoma, the two most common skin cancers. In addition to increasing your risk of skin cancer and accelerating signs of skin aging like wrinkles and brown spots, UV radiation also weakens the immune system — which further increases your risk for skin cancer. While there is no question that vitamin D is essential for strong bones and a healthy immune system, current evidence does not support its role in the prevention of breast cancer, colorectal cancer, heart disease and stroke. Adults should obtain their recommended daily dose of 600 IU (international units) of vitamin D safely, from foods such as oily fish and fortified dairy products and cereals. Another easy way to ensure you are getting enough vitamin D is to take supplements. I strongly advise against exposure to artificial UV radiation (tanning beds), since the health risks — including skin cancer and premature skin aging — are significant and potentially life-threatening.

But should we test everyone for vitamin D deficiency?

There are problems with making vitamin D tests a standard part of preventive medicine, a federal panel said. The U.S. Preventive Services Task Force said Monday there’s not enough evidence of benefits or harms to recommend vitamin D testing for all. And even though some studies have associated low levels of vitamin D with a long list of ills, including a higher risk of fractures, falls, heart disease, colorectal cancer, diabetes, depression, thinking problems and death, scientists who evaluated studies for the USPSTF say there is no direct evidence that universal screening would reduce those risks. “The effect of vitamin D levels on health outcomes is difficult to evaluate,” the recommendation statement says.

So what do I do for now? I get outside in the sun when it appears. Walking my dog helps. And I do take a Vitamin D pill in the lowest sun months. Given the above I’m not sure it’s doing me any good but it’s a low enough dose that it’s not doing me any harm either.

What do you do about Vitamin D in the winter? Why? (And although I’m a professor and this is exam season, I don’t mean that question in an exam like way! I’m curious about what decisions others make when it’s not clear what the facts are.)


13 thoughts on “Vitamin D: What’s a reasonable person to do?

  1. I’m always up in the air about whether or not to take it. I suffer, a bit, from seasonal effective disorder and find the winter months so awfully long. I do take 1000 mg daily from November to March but I’m not really convinced it does anything. The best option, for me, is to just keep walking those dogs and myself for as long as I can tolerate being outside.

  2. I do take vitamin D, but not every day.
    Once a week, I take a ‘cocktail’ of vitamin D, vitamin K, calcium, zinc and magnesium.
    And once or twice a week (during the winter) I take calcium with vitamin D.
    Other than that: get outside as much as possible with my desk job, and eat a balanced diet.

  3. Vit D first hit my radar after I was diagnosed with MS in 2003. Demographics indicate that MS tends to be concentrated in more northern latitudes and is highest in Scotland and Canada (Alberta specifically). Other research indicates that people with MS are more likely than the general population to be born in May and who were therefore in utero during the dark winter months.

    Fly in the ointment – Inuit populations do not have an abnormally high concentrations of MS which would be expected if lack of sunlight and therefore Vit D was the culprit. So then researchers looked at fish intake, thinking that omega fatty acids somehow protects them… And so on and so on.

    Me? I try to remember to take 2000IU a day during the winter months. I’ve never had my levles tested. Anecdotally, I think my mood is better when I take Vit D regularly during winter, or when I get to go to the beach often. I do wonder about sunscreen and it’s effects on natural Vit D production and what the risks and benefits may be.

    Interesting topic, thanks for posting Sam.

    1. Since being diagnosed with lupus SLE & Wegeners Granulomatosis I take 2000mg during the summer months but in winter I increase from 4000 – 6000mg depending on flares.
      It’s important I have learnt that treating my body as a temple I can keep dosages to the lowest possible which allows balance in all areas of mind body and spirit health.

      1. Thank you for commenting! I was diagnosed with MS in 2008, and my D is low every time it’s tested at my neurologist. I do the prescribed 50,000 IU regemine and it gets back into the normal range for about a year or until it’s tested again. I supplement OTC in the winter months (I live in New England) about 800IU a day (or whenever I remember to take it). I think it improves my sleep and energy a bit, and since fatigue is my primary MS symptom, that’s helpful. But I’m not sure if it’s a placebo effect. I wonder if those of us with MS and AI disease just do t absorb it as well, or if the constant state of inflammation we are in chews through what we do take. I don’t know.

  4. I take 2000mg of vitamin D, but I don’t feel a noticeable effect. I may increase the amount I take to 4000mg. I take it because I have anxiety and OCD and they get worse in the winter because of the earlier nighttime…so this winter, I’m hoping it staves off the seasonal moodswings I get!

  5. I take Vitamin D supplements in the winter season, when the hours of sunlight north of the 49th parallel dwindle and my mood seems to founder. My anecdotal experience is that it seems to help/doesn’t hurt, and reading the research seems to turn up controversy but some evidence for supplementation in winter in northern climes.

  6. I always wonder what to do for my kids especially. They are not at an age where they can decide for themselves whether or not to risk skin cancer for vitamin D sufficiency. But they also don’t drink a lot of milk that has it added in and wouldn’t absorb the full amount anyway. I’m just curious as to how they know “how much” vitamin D we need and if anyone was ever sufficient in that proposed amount without being subject to the harms of UV rays?

  7. Interesting point AmberLynn. How much is enough? How low is deficiency? Who determines these parameters and why? Is there agreement about the parameters? Repeat for UV exposure and add how much is too much/enough? Is all UV exposure bad? How healthy are sunscreens? Are they regulated and/or researched with regard to potentially toxic effects (especially given that we slather it on thick and often and do the same with children). I have more questions than answers for sure.

  8. I don’t take any Vitamin D supplements. Since I don’t own a car (and by choice for last few decades), I must walk, cycle or take transit in winter nearly daily, so I think I’m getting enough Vitamin D. I have milk in my cereal, etc. daily.

    Calgary also has more sunny days than Vancouver and Toronto.

    I’m not concerned. I should be more concerned about calcium and iron intake.

  9. As a background, I live in Norway (about 3°south of the arctic circle) which means the hours of sunlight from November – March are minimal. Currently I am blessed with 4 hours of daylight (10am-2pm); most of that is not direct sunlight though. The sun barely rises above the horizon and is mostly blocked by the mountains. In total, I get around 1.5-2hrs of direct sunlight, if it’s not cloudy, snowy, rainy). All that being said, vitamin D deficiency is a serious concern for me and the people in my country. So how do we get enough?

    Some will use of the 5+ weeks of vacation to head somewhere sunny/warm and refresh that way, but given that it’s not always possible we turn to other options.

    Most get their vitamin D through diet: Eggs and lots of fatty fish (salmon, mackerel, trout) and the average Norwegian eats fish 2-3 times a week as a main meal (and more if you count it as a small snack/lunch), Orange juice, milk and many of the dairy products here are also enriched with Vit.D. My breakfast this morning was two open-faced sandwiches, 1 with mackerel in tomato and 1 with egg and smoked salmon (both with enriched vit.D margarine) with a glass of milk.

    In terms of supplements, I don’t find pills all that common. A daily (year-round) spoonful of Trån or Möllers (cod liver oil) is *very* common. Tastes gross, but is good for you.

    And despite their bad reputation, it is common here to use sun beds, not for tanning and for short periods of time. (Interestingly, the Scandinavian Journal of Public Health conducted a study of sunbed use in Norway (which has one of the highest melanoma rates in the world). Their conclusions were that more work needs to be done. But also that while the rate of sunbeds is increasing in people 50 or younger, the number of cutaneous melanoma in Norway is actually decreasing in that age group. I should mention that, like almost everything else here, sun studios are heavily regulated by the state. One other article linked the high CM rates with the older generation’s summer-time activities without using proper protection. The article: Scand J Public Health 2013 Dec: 41(8) “Sunbed use and cutaneous melanoma in Norway”).

    Otherwise I get outside when I can and fight through the depths of winter on skis or skates waiting for the nearly 21 hrs of sunlight I get in June/July.

  10. I take vitamin D supplements. Maybe they work, maybe they don’t. But what I *do* notice is very helpful is high intensity aerobic activity. If I do 30-60 minutes/day it provides a noticeable boost to my mood, concentration, and productivity. It is as noticeable and as quick acting for me as a cup of caffeinated coffee…

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