Vitamin D: Are you getting enough?
Did you know that 1 BILLION people worldwide and about 35% of adults in the US have a Vitamin D deficiency? This is mostly due to people spending less time out in the sun (the best source of Vitamin D), and vigilant sun protection, since sunscreen with SPF 30 reduces Vitamin D production by 95%. It is estimated that most people need 1000-1500 hours of sun exposure throughout the spring, summer and fall to obtain the necessary amount of Vitamin D.
Vitamin D is a fat-soluble vitamin used by the body to build and maintain strong and healthy bones. It does this by increasing the absorption of calcium, magnesium, and phosphate. A deficiency can lead to rickets (kids) and osteoporosis (adults), which then increases the risk for fractures. Fortifying milk in the 1930s helped to prevent rickets, but many people are still at risk. If you are one of the many who swapped out dairy products for nondairy foods, make sure these foods are fortified with Vitamin D and calcium. Some studies are also linking Vitamin D deficiency to cancer, cardiac disease, diabetes, autoimmune diseases, and depression. The only way to test for a deficiency is with a blood test.
About 50-90% of vitamin D is absorbed through the skin via sunlight while the rest comes from the foods you eat. Twenty minutes of sunshine daily with over 40% of skin exposed (think: arms and legs) is required to prevent Vitamin D deficiency. Certain medications and conditions such as celiac disease, short bowel syndrome, gastric bypass, and cystic fibrosis affect the absorption of Vitamin D and increase the risk for a deficiency.
Supplements are not always necessary, as the skin produces vitamin D that can last at least 2x as long as the vitamin D you take in through foods or supplements. It can also be obtained through other sources - fatty fish (such as tuna, mackerel, and salmon), foods fortified with vitamin D (dairy and nondairy products, soy milk, and cereals), beef liver, cheese, and egg yolks. Of course, vitamin D supplements are needed for people most at risk for deficiency, including breastfed infants, older adults, people with limited sun exposure, darker skinned individuals, and overweight individuals.
Your GUIDE to Vitamin D
Important for: Bone health, heart function, muscle development, immune system, mood regulator
Deficiency symptoms: Bone and/or muscle pain, difficulty losing weight, frequently sick, fatigue, mood swings, hair loss, impaired hearing
Blood test: 30-80 ng/ml = normal, 50-80 ng/ml = optimal
Daily needs: RDA: 400-800 IU (10-20 mcg); 1000-4000 IU (25-100 mcg) often needed to maintain optimal levels
For reference, 800 IU = 3 oz sockeye salmon, 2 eggs, and 8 oz milk
Best sources: Sunshine (w/o SPF), fatty fish, eggs, dairy, beef liver, fortified foods
Absorption: Include vitamin D rich foods in meals with healthy fats, such as olive oil based-dressing, and Vitamin K rich foods such as kale to increase absorption
Supplements: Can be beneficial in the winter months when people spend more time indoors and the sun is not very strong. Look for Vitamin D3 (different than D2) at a daily dose of 2000 IU/day. Be sure to take it with a meal and foods with Vitamin K to help with absorption, as noted above.
So how much is too much? For adults, toxic effects increase above 4,000 IU per day.
Takeaway: The best way to get Vitamin D is through a combination of direct sunlight in warmer months, foods, and lastly supplements when a blood test confirms a deficiency.
Here is a list of Vitamin D rich foods