This article is the first of an ongoing series on fat-soluble vitamins, covering those that are integral to health and healing from chronic illness but often lacking in the modern diet. Check out my article on the importance of vitamin K, and Angie’s articles on vitamin A and vitamin E.
Vitamin D has been in the news a lot lately, partially due to the discovery of its pivotal role in optimal health, combined with the finding that most of us are at least a little, if not very, deficient. As it applies to those of us with autoimmune disease, vitamin D can be one of the most powerfully restorative nutrients, given its effect on the immune system (Angie used it to recover from gluten exposure a couple years ago — click here to read more). While taking a D supplement is part of many doctors’ treatment protocols these days, it is important to note that you still need to exercise caution as overdoing it can definitely be harmful. Read on to educate yourself about this essential nutrient, as well as to learn about how you can determine how much you need and what kind to exercise the safest and most informed approach.
What is vitamin D?
Vitamin D is a steroid hormone that is made in your skin as a response to ultraviolet light. It is also found in your diets to varying degrees as well as in supplement form. The most common forms of Vitamin D are ergocalciferol (otherwise known as D2) and cholecalciferol (otherwise known as D3). When your skin is exposed to light, specifically the UVB spectrum of ultraviolet light (outdoor sunshine at the optimal time of day and year), it synthesizes vitamin D from a cholesterol precursor.
Beyond being a vitamin that your body can actually make, vitamin D has a couple of other notable characteristics. It is fat-soluble, meaning it is best absorbed in the presence of fat, and is also stored in fatty tissues and liver. This is important to note because since it is easy for the body to store, there is a higher potential for toxicity with vitamin D.
What does vitamin D do in the body?
Vitamin D is most well known for regulating the amount of minerals like calcium, magnesium, and phosphorous in the body. In recent years, there has been much research into additional functions, like its effect on the immune system, cardiovascular system, and cancer. Here is a list of what vitamin D does in the body:
- Regulates bone mineralization and metabolism
- Controls the expression of over 200 genes
- Modulates the immune system
- Controls cell growth
- Has anti-inflammatory and anti-carcinogenic properties
- Supports the immune system fighting infection
- Assists in neuromuscular function
As you can see, vitamin D has a variety of functions in many areas of the body, making it all the more important that our levels are optimal.
What does deficiency look like?
Extreme vitamin D deficiency manifests itself as rickets, where bones grow soft and weak in children, and osteomalacia, the softening of bones in adults. Research is beginning to identify what earlier signs of deficiency look like, which can be difficult to pinpoint because they are usually non-specific (not pointing to a clear disease or condition). Often the first signs are tiredness, muscle pain, and more frequent susceptibility to the cold and flu. Sound familiar?
It is estimated that up to 75% of Americans are deficient in vitamin D. This isn’t surprising, considering our modern, indoor lifestyles, obsession with sunscreen, and lack of nutrient-density in our diets. Here is a list of some of the possible symptoms that can result from varying severities of vitamin D deficiency:
- Tiredness, malaise, fatigue
- Aches and pains
- Frequent infection
- Cardiovascular disease
- Cognitive impairment
How do you get vitamin D?
There are three ways of obtaining vitamin D, and they differ in ease and safety.
- Smart sun exposure — The safest (if done properly) and sometimes simplest way to get vitamin D is through regular exposure of your skin to sunlight. It is also the most fun, and can be convenient when paired with another healthy activity like walking, gardening, or spending time with loved ones. 15 to 20 minutes of exposure on arms and face at least a few days a week should be enough for most people (see note below for more guidelines). You should always take care to exercise caution in the sun and never be outside so long without protection that your skin burns.
- Diet — You can get small amounts of vitamin D in fatty, cold-water fish like sardines, herring, and mackerel, as well as beef liver and pasture-raised pork. These foods also happen to be incredibly nutritious otherwise, so eat up! Cod liver oil can also be a good source of vitamin D in the diet (I consider this more of a “real food” than a supplement because it is not highly processed and standardized like a supplement would be). Although dietary vitamin D is unlikely to meet your body’s requirements, its definitely reason to include these nutrient-dense foods in your diet!
- High-quality supplementation — for those who don’t or can’t get enough natural sun exposure (like those of us who live at northern latitudes in the wintertime!), a supplement may be warranted (see below for guidelines on choosing one). For those who find themselves mildly to severely deficient, a high-quality supplement can help get your levels up quickly. A note of caution — it is easy to get vitamin D levels too high by taking an excessive dose or a prolonged supplement, so make sure to test and have a doctor review your dosage here.
Wait — I thought exposing my skin to the sun causes cancer?
When we expose our skin to sunlight, we get a mix of ultraviolet rays — known as UVA and UVB. UVA rays are the those that are most implicated in skin cancers like melanoma, and deeply penetrate the layers of our skin. UVB rays, in contrast, are responsible for tanning and the effects of sunburn, and only penetrate the surface layers. UVA rays are not only deeper penetrating, but affect us through windows, clouds, foliage, and their strength changes little in intensity throughout the year. UVB rays have much less intensity, especially during the winter months when the sun is lower on the horizon. They also are blocked easily by glass, clouds, clothing, and other barriers.
Want to learn something crazy about sunscreen? The SPF factor refers to a product’s ability to block UVB rays, but not the deeper penetrating, cancer-causing UVA rays. Most sunscreens offer mild, if any protection from UVA rays. What is worse, is that people usually apply sunscreen when there is a chance of getting a burn — at the beach in the summer months, for instance. What a lot of people don’t consider is that those same UVA rays are just as present in the cooler spring and fall months, when the lack of UVB rays cons us into thinking we are protected because we won’t get a burn as easily.
Sunscreen use can be harmful from two angles — first, it is very effective at blocking the rays that we need to produce vitamin D, and second, it is not effective at blocking the rays that cause cancer. Not to mention all of the harmful chemicals being applied directly to the skin!
The solution to this problem is to practice smart sun exposure. What does this mean? Depending on the fairness of your skin, you will want to expose yourself to sunlight without sunscreen a few times a week, for 10-20 minutes or more. Now, if you have dark skin, you may need more sun exposure to generate the vitamin D you need — this is where testing is helpful. Never stay out in the sun long enough to burn. Cover yourself or use a safe sunscreen if you are going to be outside for a prolonged period of time. Pay attention to the seasonal differences that affect the strength of the sun — time of day, latitude, and season (an awesome app for this is called D Minder), as this will effect the strength of the sun’s rays and the duration you can stay exposed for.
How do I tell if I’m getting enough vitamin D?
I’m a big believer in test, don’t guess. It is important for you to have your vitamin D level tested at least once a year, so that your doctor can pinpoint a deficiency, you can gauge how well your supplementation is working, as well as see if you are edging towards having too much vitamin D. While you can test any time, I like to test in the middle of winter, around January or February because it is when I’m most likely to be deficient.
What kind of levels are you looking for? The optimal level is currently up for debate, with the Vitamin D Council recommending a range of 40-70 ng/dL, with an ideal sitting at 50 ng/dL. Many practitioners who work with autoimmune patients recommend on the higher end of that spectrum, due to the immune-modulating and anti-inflammatory properties of vitamin D. That being said, other researchers in the ancestral health community, such as Chris Kresser and Chris Masterjohn, are recommending levels that are a bit more cautious, 25-50 ng/dL with an ideal at 35 ng/dL.
In the past, I’ve personally shot for my level to be over 50 ng/dL but the past couple of years I have maintained a lower level at 40 ng/dL and haven’t noticed a difference, for better or worse (I should note also, that I did notice a big difference when I started supplementing when I was diagnosed with a deficiency of 15 ng/dL five years ago). Your ideal is best determined through working with your doctor, as well as a little trial and error.
Can you get too much vitamin D?
Vitamin D toxicity is possible, and unfortunately common in those who supplement without proper testing and follow-up from their doctor. I recently had a family member test at 110 ng/dL after their doctor told them to take a high-dose of vitamin D, without giving them instructions for retesting or tapering off. Since it is easily stored by the body in fat tissues as well as the liver, it takes awhile for those levels to come down if there is an excess.
Elevated levels of vitamin D can cause a buildup of calcium in areas of the body where you don’t want them — soft tissues like the blood vessels and kidneys. This is usually only seen in people who supplement with high doses of vitamin D.
An important reminder — vitamin D has a synergistic relationship to the other fat-soluble vitamins A and K2, and research shows having adequate levels protects against toxicity. If you are supplementing with vitamin D, it is a good reminder to eat vitamin A-rich foods like liver and other organ meats, and fatty, cold-water fish. K2 can be obtained in small amounts from fermented foods and made in the gut by your flora, but you might consider talking to your doctor about a supplement here if you suspect ongoing gut issues or remain on the elimination diet long-term.
If I need to take a vitamin D supplement, which form should I choose?
Even if you make a good effort to get your sun exposure naturally, it can be difficult and even impossible for you to get enough to have your vitamin D levels in the optimal range. In the winter, the sun is too low on the horizon at most latitudes for your skin to manufacture enough vitamin D (that is, unless you live somewhere tropical!). I do my best in the warmer months to get sun exposure naturally, combining this task with time spent outdoors exercising, gardening, or relaxing. In the winter, I take a supplement at a dosage that past history based on supplementing and testing tells me will maintain my levels.
Look for a vitamin D3 (cholecalciferol) supplement, ideally carried in a fat since the vitamin is fat-soluble and will be better absorbed by your body that way. I’ve personally used this product as well as this product, and both are favorites because they are carried in fats, have no other fillers, and are super easy to take with the droppers.
Another reminder to make sure to check with your doctor to rule out deficiency and determine an optimal dosage for your body. Although most people are likely to be deficient in vitamin D and taking a moderate dose initially is unlikely to be harmful, I don’t recommend blind supplementation, especially after you are a few months in.
Has correcting a vitamin D deficiency been an integral part of your healing journey? Let me know in the comments!