Just How Important Is Vitamin D?
Today, we’re going to discuss vitamin D and its importance in the body.
What Is Vitamin D?
Vitamin D is a fat-soluble vitamin. Because the body can create its own vitamin D, it is technically not a vitamin, but a pro-hormone, a precursor to the hormones the body needs to function. Vitamin D has no active role in the body other than to be converted to usable hormones by the liver and kidneys.
This vitamin (we’ll stick with vitamin since that’s how it’s known commonly) is responsible for maintaining blood levels of calcium and phosphorus, growing bone, and shoring up the immune system. Let’s have a look at a few of the issues that are caused by a vitamin D deficiency.
What If I Don’t Get Enough Vitamin D?
Extreme deficiency of vitamin D during childhood results in a disease known as rickets. However, the importance of vitamin D in bone health doesn’t end in childhood. In adulthood, the bone softening diseases osteomalacia and osteoporosis have been associated with low vitamin D status. In fact, the Nurse’s Health Study found that vitamin D did more for bone health than did calcium.
These data support a possible role of vitamin D insufficiency in PD [Parkinson's Disease]. Further studies are needed to determine the factors contributing to these differences and elucidate the potential role of vitamin D in pathogenesis and clinical course of PD.
The results showed that vitamin D elicited a two-fold increase in nerve growth factor mRNA in both the hippocampus and cortex, suggesting a possible role in the treatment of neurodegenerative disorders such as Alzheimer’s disease.
It looks like it also helps protect against some skin infections:
A study led by researchers at the University of California, San Diego School of Medicine suggests that use of oral Vitamin D supplements bolsters production of a protective chemical normally found in the skin, and may help prevent skin infections that are a common result of atopic dermatitis, the most common form of eczema.
Rheumatoid Arthritis? Yeah, it handles that too.
Both dietary and supplemental vitamin D intake were inversely linked with rheumatoid arthritis risk, the authors found. High dietary (at least 290 IU/day) and supplemental (at least 400 IU/day) intake were associated with 28 percent and 34 percent reductions, respectively, in the risk of rheumatoid arthritis.
How’s this for irony? Vitamin D protects against skin cancer.
The results of the current study demonstrate that much of the geographic variation in cancer mortality rates in the U.S. can be attributed to variations in solar UV-B radiation exposure. Thus, many lives could be extended through increased careful exposure to solar UV-B radiation and more safely, vitamin D3 supplementation, especially in nonsummer months.
And here’s an interesting finding: Vitamin D may be protective against radiation.
Writing in the International Journal of Low Radiation, Hayes explains that calcitriol, the active form of vitamin D, may protect us from background radiation and could be used as a safe protective agent before or after a low-level nuclear incident.
This is all just the tip of the iceberg too. Congestive heart failure, numerous cancers, Multiple Sclerosis, Type I Diabetes, and high blood pressure have also been linked to low levels of vitamin D.
Where Can I Find Vitamin D?
For humans, there are two ways of getting vitamin D. The body can create vitamin D in the skin when it is hit with UVB radiation. Or the body can get vitamin D from dietary sources. Ultimately however, all vitamin D in the food-chain begins with some action of an organism with sunlight. So obviously, the first place you can turn to get some vitamin D action going on is the source of the UVB rays that help the plant and animal kingdoms make the vitamin in the first place. A little sunlight isn’t going to cause skin cancer. Recall above that vitamin D deficiency actually predisposes one to skin cancer. Of course, that’s not freedom to go sunbathe for hours on end.
Dietary Vitamin D Sources
So if you are either scared of the sun or live much above the sub-tropical zones, it’s going to be hard to get enough vitamin D from the sun. Luckily, there are some rich sources of the vitamin that fit perfectly into a lifestyle of eating real foods.
- Cod liver oil – 1tsp, 450IU
- Salmon, cooked, 3 1/2 oz: 360 IU
- Mackerel, cooked, 3 1/2 oz: 345 IU
- Sardines, canned in oil, drained, 3 1/2 oz: 270 IU
- Pork lard, 1 tbsp – 140IU
- Beef Liver, cooked, 3.5oz – 30IU
- Whole Egg – 25IU
An important thing to note on the fish though is that farmed fish is less likely to have those levels of vitamin D. Wild fish live on algae and other fish, which at the base of the food chain live on algae. Farmed fish live on grains and other such unnatural food.
Of course, I don’t typically advocate focusing on a single vitamin at the expense of others, and this one is no exception. But if you’re eating real foods and getting some sunlight in your life, you probably have little to worry about. Notice that a single teaspoon of cod liver oil gets you the recommended amount of vitamin D for two days. So it’s really not that hard to meet your vitamin needs when you eat foods that are naturally rich in vitamins.
How Much Vitamin D Do I Need?
There is technically no RDA for vitamin D as there is insufficient evidence to establish one. However, there are guidelines to give an Adequate Intake. They are:
- Ages 19-50: 200 International Units (IU)
- Ages 51-69: 400 IU
- Age 70 and older: 600 IU
It’s theoretically possible to overdose on vitamin D, but with natural sources of the vitamin, it’s unlikely. In the winter months, adding a teaspoon of cod liver oil to your diet can ensure that your sunless existence doesn’t lower your vitamin D intake.
EDIT: I want to add more information about optimal vitamin D intake. The above amounts are basically the RDA, which we all know are extreme low-level amounts to merely avoid gross deficiency. Much, much higher amounts can be taken to ensure vitamin D status is maintained at a sufficient level.
In his post How Much Vitamin D Should I Take?, Dr. William Davis recommends a blood level of D3 of 60-70 ng/ml and recommends getting as much D3 as is required to achieve such a level. That means getting out in the sun and letting the body make its own vitamin D as it is designed to do. Of course, to understand your current vitamin D level, you must have an inexpensive test run by your doctor. Here is part of Anna’s comment below to help you understand what test to get:
The test for the amount of Vit D3 stored in the body is called 25 (OH) D. It is increasingly common to have it ordered by primary care physicians (not the 1,25 (OH) D test; it isn’t the right level to test. Even if your doctor doesn’t offer Vit D testing, you may find they will order it without a problem if you ask; mine did. It’s a simple blood test.
Given all of the issues resulting from a lack of vitamin D, does it seem a good idea to slather every inch of your skin with sunscreen before walking to your car?
What are your main sources of vitamin D? Do you get unprotected sun exposure?