The sun is out. The weather is warmer. Summer is almost here! With the gorgeous sunshine outside, it’s a great way to get your daily Vitamin D. Temperatures are rising and there are more hours of sunshine each day. Spring often is associated with increasing mood level, but there is another interesting health benefit accompanying spring… increased production of the vitamin D.
With exposure to UV light from the sun, a metabolite of cholesterol found in the skin is converted to vitamin D. During the winter time, the UV light is not as strong and most people cover most of their skin to preserve heat so less vitamin D is made in the skin and more must be consumed. Rising temperatures allow more skin to be exposed to the UV radiation, leading to an increase in vitamin D production. However, there is a catch, production of vitamin D in the skin only happens when the UV light is not blocked by sunscreen. The good news is, a full supply of the vitamin can be produced from unprotected skin exposure just 10-15 minutes 3 times/ week. All other times, be sure to apply a SPF of 45 or greater when spending time in the sun.
Vitamin D is needed for promoting bone mineralization, absorption of calcium and phosphorus from food in the intestines, and reabsorption of calcium in the kidneys, as well as modulating neuromuscular and immune function and reducing inflammation. Adequate intake for adults between 19 and 50 should be 200 international units (IU) of Vit D, 400 IU for those older than 51-70 years, 600 IU for people older than 70.
The American Academy of Pediatrics recommended that all exclusively breastfed infants receive a daily 400IU vitamin D supplement. However, adequate levels of Vitamin D are still up for debates among experts, and many experts are suggesting a daily intake of 800 to 1000 IU of Vitamin D per day. Low levels of Vitamin D are very common in the US, and even more common in areas with less sunshine.
Sources of Vitamin D: self-synthesis from at least 15 minutes of direct sunlight, cod liver oil, fatty fish such as herring, catfish, salmon, mackerel, sardines, tuna, & eel, egg yolk, beef liver, as well as fortified cereals, milk, and juice.
Benefits of Vit D: Studies have shown that there are benefits for people with higher vitamin D levels. Vitamin D plays a role in absorption of calcium for our bones, decreasing risk of colon cancer, and lowering risk of developing Type II diabetes. In addition, vitamin D also contributes to improving pregnancy outcomes: decreasing the “risk of pre-eclampsia, improving length of gestation, birth weight, and infant bone mineralization”. Other studies have shown that people who are deficient in Vitamin D have a higher risk of cardiovascular disease. However, one should note that too much vitamin D can have potential adverse effects on the cardiovascular system and allergies.
People who may be at risk for Vitamin D:
- People with limited sun exposure: Not feeling the sun on our skins most likely means we’re not self-synthesizing vitamin D on our own
- People with darker skin: People with fair skin are more efficient at synthesizing vitamin D from sunlight because they have less melanin.
- People with fat malabsorption problems: Since vitamin D is a fat-soluble vitamin, individuals with fat malabsorption issues like celiac disease, liver disease, Crohn’s disease and pancreatic insufficiency might not be able to absorb enough vitamin D.
- Vegans & vegetarians: Supplements may be needed since fish, eggs, and milk are often limited or avoided in their diet.
- People who are either lactose intolerant or avoid milk in their diet: Be sure to get vitamin D from other sources, such as fortified cereals and juice!
- Babies who are exclusively breast-fed. Breast milk doesn’t contain enough vitamin D for the needs of the infant. So the American Academy of Pediatrics recommends that babies who are exclusively breast-fed be given a supplement of 400 IU of vitamin D daily.
- Adults over age 50. As we age, our skin is less efficient at making vitamin D, and our kidneys are less efficient at converting Vit D to a form our bodies use.
Aim for 800-1000 IU of Vit D a day!
Assistance provided by Rachel Yam and Kaylee O’Connell