Vitamin D
What is it: Vitamin D is in a class all it's own because it's actually a steroid hormone produced in your skin when exposed to sunlight. Vitamin D deficiency is actually quite wide spread in America with 41.6% of the population being deficient for their age group. The good news is that we can choose foods and supplements that assist in ensuring we are getting enough Vitamin D which we will discuss below in more depth. Vitamin D is a fat-soluble vitamin and comes in two main forms.
- Vitamin D3 (cholecalciferol). Found in some animal foods, like fatty fish and egg yolks.
- Vitamin D2 (ergocalciferol). Found in some plants, mushrooms, and yeasts.
Being fat-soluble means our body can store this vitamin for later use which helps reduce the risk of deficiency. Of the two types of Vitamin D, it's been shown that Vitamin D3 is more effective than D2 in increasing the levels of this vitamin in the body. Nearly twice as effective according to studies conducted at the National Institutes of Health which we will link below.
Functions/Benefits: Vitamin D converts into two forms in our bodies. The first is done in the liver where it is converted into calcidiol and stored for later use. The second conversion takes place in the kidneys where Vitamin D is converted to the active steroid-hormone form called calcitriol. Once this second form of conversion takes placed it binds with receptors on each cell to tell the body to turn genes on or off so the body can function properly. This regulation is critical to cellular function and overall health which is why it's important to ensure we aren't deficient in Vitamin D.
Healthy levels of vitamin D is linked to better bone density, strength in our limbs, and reduced risk of diabetes, cancer and mortality. Adequate levels of vitamin D have also been shown to manage the symptoms of those dealing with clinical depression. Although more studies are needed to delve deeper into the benefits of vitamin D, the importance of this in the health of our bodies cannot be denied.
Food Sources: Vitamin D can be found in various food sources if you aren't getting enough sun exposure or taking a supplement. Cod liver oil, fatty fish such as salmon and mackerel are some of the best sources! Mushrooms also provide some Vitamin D and exposing them to ultraviolet light can boost the vitamin D content of mushrooms. Nearly the entire U.S. milk supply is fortified with vitamin D as well as many plant based alternatives.
Deficiency/Toxicity: Vitamin D deficiency effects nearly half the population of Americans. Limited sun exposure, covering of the body, and poor dietary choices can all be factors of this. Just 5-10 minutes of sun exposure can help the body synthesize the production of vitamin D, but if your doctor finds you need more, there are supplements and foods you can choose to assist in ensuring the proper levels are being met.
Symptoms of vitamin D deficiency can be mild and often time takes years to develop to the point of someone taking notice. People with low levels of vitamin D are at higher risk of osteoporosis, heart disease, diabetes, cancer and autoimmune diseases. In general a vitamin D deficiency over a lifetime is linked to reduced life expectancy.
It's important to ensure that your diet is varied and healthy so that other vitamins are not lacking because vitamin D works with other vitamins to ensure proper functions take place in the body. It works with other vitamins like A, K and magnesium to promote overall healthy functions and a deficiency in any of these vitamins can throw off important processes in our systems.
Fun Factoid: Vitamin D holds the nickname 'The Sunshine Vitamin' due to our body's natural ability to create it when exposed to sunlight.
| Life Stage | Recommended Amount |
|---|---|
| Birth to 12 months | 10 mcg (400 IU) |
| Children 1–13 years | 15 mcg (600 IU) |
| Teens 14–18 years | 15 mcg (600 IU) |
| Adults 19–70 years | 15 mcg (600 IU) |
| Adults 71 years and older | 20 mcg (800 IU) |
| Pregnant and breastfeeding women |
15 mcg (600 IU) |
Below are sources and further studies to review on Vitamin D.
Vitamin D 101: A Detailed Beginners Guide
Prevalence and correlation of vitamin D deficiency in American adults
Vitamin D Fact Sheet for Health Professionals
Vitamin D Fact Sheet for Consumers
A review of health consequences of the vitamin D deficiency pandemic
Dietary reference intakes for calcium and vitamin D