When it comes to food, fortified milk and orange juice, as well as egg yolks and some types of (UV-irradiated) mushrooms contain small (as in, practically obsolete) amounts of vitamin D2 (the much less bioavailable and effective form of the micronutrient). For example, native food sources of vitamin D3 include fatty fish-like salmon.
Even to meet the recommended daily intake (i.e., 600 IU for healthy adults, according to the National Academies) to prevent bone health problems, one should eat more than six glasses of fortified milk per day, 12 whole eggs, or a 3-ounce serving of sockeye salmon. .5 ounces, and experts agree: 600 IU isn’t far enough from the fat-soluble nutrient to push the needle on vitamin D status to reach (and maintain!) healthy levels.
As previously mentioned, nationwide rates of frank vitamin D deficiency and insufficiency [i.e., 25(OH)D blood test results less than 20 ng/ml or 30 ng/ml] among adults is 29% and 41% respectively. But racial inequalities clearly exist, with 82% of Black Americans and nearly 70% of Latino Americans having a D deficiency.
Looking at how much vitamin D we put in our mouths each day, nationally representative research shows that between 93 and 100% of the US population doesn’t even get 400 IU of vitamin D a day.
With this in mind, Holick recommends all of his clients take a daily vitamin D supplement regardless of the season. Drake agrees, stating that the Linus Pauling Institute generally recommends healthy adults take 2,000 IU of supplemental vitamin D each day, but notes that achieving ideal blood levels of vitamin D (i.e., above 30 ng/ml” danger zone” for insufficiency and in that coveted 50 ng/ml range) may require an even higher dose of supplementation.
mbg’s vice president of scientific affairs, Ashley Jordan Ferira, Ph.D., RDN, breaks down precisely How much we need vitamin D to achieve healthy serum levels: “Pharmacokinetic studies show that 100 IU of vitamin D is needed to increase the serum D levels of a normal weight adult by about 10 ng/ml. So that means that to reach 50 ng/ml, you need 5,000 IU of vitamin D per day.” She explains, saying, “Since two-thirds of our country is overweight or obese, our daily vitamin D requirement as a country is actually higher, but 5,000 IU is a good starting point.”
If you’re trying to do some quick mental calculations to determine how many servings of milk, eggs, or fish you would need to eat to consume 5,000 IU of vitamin D daily, we’ll save you the trouble – it’s a lot† Too much, one would be fair to argue. Simply put, daily vitamin D supplementation is the most effective way to achieve adequate vitamin D levels and maintain whole-body health.*
(Looking for a truly effective D3 supplement that will help you achieve and maintain adequate vitamin D status? Check out our roundup of vitamin D supplements.)