Are you getting enough vitamin D? The short answer to this question is: maybe not.
It’s estimated that around half of the population in the United States is vitamin D deficient. And the rate goes up by an additional 15% during the winter months.
So, why does that matter? Does our nutrition play a role? And what can we do about it? Read on for answers.
Vitamin D: The Basics
Vitamin D is essential for good health. It is a fat-soluble vitamin with hormone-like properties that is found naturally in very few food sources. It is also synthesized in our skin after exposure to sunlight.
Why is it important?
Vitamin D has many important roles in our health. It is best known for it’s positive affect on bone health as it helps absorb calcium in the small intestine. Therefore, vitamin D can aid in better bone production in children as well as prevention of bone loss in adults.
Newer research suggests that vitamin D is also helpful for the following:
- boosting immunity by increasing protection against bacteria and viruses
- improving brain health and cognition
- treating mood disorders, like depression and seasonal affective disorder
- reducing overall inflammation
- promoting strength through stimulation of muscle contraction
- protect against certain cancers and type 2 diabetes
Having low levels of vitamin D can result in bone and joint problems and lowered immunity. Studies are also finding a link between vitamin D deficiency and certain diseases and disorders. It’s important that we get enough of this vitamin for good health and quality of life.
How much do we need?
Generally, current recommended daily allowance for vitamin D is: 200 to 800 International Units (IU) daily for infants less than one year, 400 to 800 IU for children and adolescents from 1 to 18 years, and 600 to 1,000 IU for all adults.
It is rare but possible to get too much vitamin D. Because it is fat-soluble, it can build up in our bodies and cause toxicity and negative side effects. It’s best to limit total intake to no more than 4,000 IU per day to prevent risk of toxicity.
Sources of Vitamin D
Vitamin D from the Sun
Vitamin D is deemed the “sunshine vitamin” because the sun’s ultraviolet rays cause our skin to produce it. Once the skin is exposed to sun, the process begins. An inactive form of the vitamin is then metabolized by our liver and kidneys to create the active form of Vitamin D, also known as calcitriol. This is our biggest and most potent source of vitamin D.
But several factors can impact the amount of vitamin D absorbed during this process. If a person’s kidneys or liver are not working properly, the conversion to the active form may be negatively affected and therefore risk of deficiency goes up.
Clothing, sunscreen, and the amount of melanin in a person’s skin can also interfere with absorption. Darker skin seems to block more of the ultraviolet rays that produce vitamin D. And covering the skin with clothing or sunscreen with a SPF of 8 or greater blocks the ultraviolet rays that are necessary for synthesis.
Vitamin D from Food
Very few foods naturally contain vitamin D. The best sources are fatty fish, eggs, liver, and mushrooms that have been exposed to ultraviolet light. There are also a number of foods that have been fortified with vitamin D, such as dairy, cereals, and fruit juices.
Here is a list of the common food sources and amount of vitamin D per serving:
- Rainbow trout (3 ounces cooked): 645 IU
- Sockeye salmon (3 ounces cooked) 570 IU
- Cod liver oil (1 teaspoon): 448 IU
- Egg yolk: 44 IU
- White mushrooms (1/2 cup): 366 IU
- Fortified milk (1 cup): 100-144 IU
- Fortified orange juice (1 cup): 120-140 IU
Vitamin D from Nutrition Supplements
Nutrition supplements generally offer vitamin D in two forms: vitamin D2 (ergocalciferol) or vitamin D3 (cholecalciferol). Both forms are absorbed similarly, but vitamin D3 appears to be more effective at replenishing stores.
Taking a nutrition supplement that contains vitamin D may be a useful way to cover any gaps in your eating habits and sunlight exposure, especially during the winter months. Appropriate dosage would depend on a number of factors, including a person’s diet and sun exposure. But I usually recommend some form of vitamin D supplementation for many of my clients during the winter months when sun exposure is reduced.
How to Optimize Your Vitamin D
Still not sure if you need more vitamin D? The first step you can take is to test your levels. The best indicator of vitamin D status is measuring serum concentration of the 25(OH)D, which reflects vitamin D in our skin as well as vitamin D from food and supplements. Work with a healthcare provider to check your status at least once per year.
Here are some additional tips to increase your vitamin D:
- Go outside and expose your face, arms, legs or back to the sun without sunscreen for about 10-15 minutes each day. Apply sunscreen appropriately afterwards for protection.
- Eat a serving of fatty fish 2-3 times per week, and include mushrooms or fortified food sources in your diet regularly.
- Consider taking a nutrition supplement, specifically with the vitamin D3 form. It may be useful to take a supplement that has anywhere between 400-1000 IU of vitamin D3 each day.
Making sure you have adequate vitamin D levels can greatly impact your quality of life. I highly recommend discussing your own needs and goals with a healthcare provider to determine the best steps for you to take. If you’re interested in an individual nutrition consult with me, you can sign up here.
Hopefully this gives you a place to start!