Vitamin D deficiency is extremely common, which is very problematic because it plays such an important role in overall health. We know that it's critical to bone health and to the prevention of many serious chronic diseases like cancer and heart disease, and more and more research comes out every day highlighting its importance in other aspects of health.
We can naturally synthesize vitamin D from the sun’s UVB rays, which is why most guidelines that you'll come across say that mid-day sun exposure without any SPF to the face, arms, legs, or back for 5 - 30 minutes twice a week provides adequate vitamin D for the majority of the population. I disagree, and I think this is a misleading guideline that results in widespread vitamin D deficiency.
This guideline really only applies to fair-skinned people who live close to the equator. And even for these people, there is significant debate over whether this actually does provide enough vitamin D. It does not apply to people who live at high latitudes (ex. Alaska, Scandinavian countries, etc.), live in places that are often overcast, live in cities with a lot of smog, have darker skin (melanin, which gives skin pigment, blocks synthesis), are elderly, have autoimmune disease, and the list goes on and on. All of these people - and face it, that's already the vast, vast, vast majority of the population - would need significantly more exposure to the sun to be able to synthesize enough vitamin D to meet their needs.
But is that much sun exposure safe?
Sun exposure has many benefits outside of vitamin D synthesis, but these need to be carefully weighed against its risks - namely skin cancer and aging. For anyone who is at a reasonably high risk for developing skin cancer, the risks outweigh the benefits. This doesn't mean they should avoid the sun entirely, but they should be vigilant about using clothing and sunscreen to protect themselves - and they should not rely on the sun alone to meet their vitamin D requirements. (Remember: by limiting exposure to ultraviolet rays, you also diminish your body's ability to meet your vitamin D needs naturally.) I don't recommend relying on the sun alone to get adequate amounts of vitamin D even for those of us who are not at high risk for skin cancer. There are too many variables to be able to determine with real certainty how much sun exposure equates to enough vitamin D. And then there's the issue of premature aging, which nobody wants. Some sun exposure is important for health, but too much and you'll damage your skin.
So what do we do?
We all get some vitamin D from the sun, even the most dedicated of sunscreen users, and then we can augment that amount by making sure that we are consuming good dietary sources of vitamin D and/or are supplementing with it.
The best food sources of vitamin D are:
- liver
- fatty fish
- egg yolks
- shiitake mushrooms
- fortified foods
Liver is by far the best source, which is why I often recommend that people take fermented cod liver oil several times per week. It's more of a whole food than a traditional supplement, though you can buy it in capsules if you don't love the idea of palating a spoonful. In addition to being a good source of vitamin D, it's rich in vitamin A, vitamin K2, and long-chain omega-3 fats like EPA and DHA. Wild salmon is another great source of both vitamin D and long-chain omega-3 fats. Egg yolks, shiitake mushrooms, and fortified foods contain vitamin D, but in significantly smaller amounts.
If you are not consuming foods like liver and fatty fish on a daily basis, then it's generally a good idea to supplement with vitamin D3 (as opposed to vitamin D2). 2,000 IUs per day is a dosage recognized as safe, but I recommend having your vitamin D level tested (specifically your 25(OH)D level) and then determining how much to supplement with based on the results. People trying to raise their levels likely need a much higher dosage (often 5,000 IUs). Serum concentrations should ideally be in the range of 50 - 70 ng/ml, and that increases to 70 - 100 ng/ml if you have cancer or heart disease.
Now I'd love to hear from you. Have you had your vitamin D levels checked? Do you take cod liver oil or supplement with vitamin D? Have you noticed any differences in your overall health since starting? Let me know in the comments!