I think that most people know that Vitamin D is an important hormone and vitamin, but I don’t think that it is understood just how important it can be, I also think there is a general misunderstanding of just how deficient most of us are. This blog post will focus on sharing some key information about vitamin D, and why I think that almost everyone should supplement with it.
Some background:
Vitamin D is both a nutrient we eat and a hormone our bodies make. It is a fat-soluble vitamin that is known to help the body absorb and retain calcium and phosphorus, which are both critical for building bone. Furthermore, studies show that vitamin D can reduce cancer cell growth, help control infections, and reduce inflammation. Additionally, many of the body’s organs and tissues have receptors for vitamin D, which suggest important roles beyond what is currently known, and studies show that there are strong correlations between vitamin D levels and overall health.
Why we generally don’t get enough vitamin D from food:
Few foods naturally contain vitamin D, though some processed and GMO foods are fortified with it. D2 (or pre-vitamin D) is produced in some plants, and D3 in animals. Some foods that are naturally higher in the vitamin are:
Cod liver oil
Salmon
Swordfish
Tuna fish
Sardines
Beef liver
Egg yolk
Why we generally don’t get enough vitamin D from the sun:
Vitamin D3 can be formed when a chemical reaction occurs in human skin, when a steroid called 7-dehydrocholesterol is broken down by the sun’s UVB light. The amount of the vitamin absorbed can vary widely, and most people don’t account for these variables when considering the amount they are getting. Here are some common conditions that decrease exposure to UVB light, and therefore lessen vitamin D absorption:
Use of sunscreen (sure you’re out at the pool, but how much of your body is covered in sunscreen?)
Wearing full clothing that covers the skin (sure you took a winter walk, but how much of your skin was exposed?)
Spending limited time outdoors (most of us spend all day indoors for comfort or necessity - like work and school.)
Time of day (UVB light is not high enough to make an impact during the earlier and later parts of the day, and this varies more depending on season.)
Darker skin tones (darker skin tones have more melanin, which acts as a type of natural sunscreen - darker skin needs more time in the sun to accumulate vitamin D.)
In certain seasons and when living far from the equator, UVB light is weaker (for example, people who live in Boston can’t make adequate vitamin D from the sun for approximately 5 months out of the year, because the UVB is too weak or nonexistent.)
Window glass completely blocks UVB light (so sitting by a window in your office or diving in the sunshine gives you exactly 0 vitamin D.)
Conclusion and Recommendations:
There is still a lot of disagreement about how much Vitamin D is optimal, and how much to supplement. Luckily, despite assumptions that were made in earlier scientific studies, we now know that it is very hard to overdose on Vitamin D. Furthermore, even when you get your blood levels tested, most scientists agree that in America what is “normal” is not what is “optimal.” Depending on your location, age, size, weight, and skin color, you might want to consider supplementing with anywhere between 2,000-10,000 IU per day. In general, however, it is safe to assume that you are deficient in vitamin D, and some baseline supplementation is needed for optimal health.