This Is Exactly How Much Vitamin D3 You Should Be Taking Every Day

Nancy Rodriguez, PhD, RDN, FACSM, a professor of nutritional sciences at the University of Connecticut, says that back in her day, no one was talking about vitamin D supplements. “In the ‘60s and ‘70s, people weren’t slathering on sunscreen. We were basking in the sun with baby oil,” she says.Though such intense sun worship had its own issues (like increasing the risk of skin cancer), it also meant that vitamin D deficiencies among the general population were rare. But these days, most of us work desk jobs and when we do go outside, we slather on sunscreen. While this is great for lowering the risk of skin cancer, it also means that we’ve become a nation of vitamin D-deficient people. According to a 2022 study published in Frontiers in Nutrition, 41% of people in the U.S. don’t get enough vitamin D.Our bodies need vitamin D. The nutrient is responsible for more than 200 functions in the body, including bone strength, dopamine production (key for feeling happy), brain health, and immune support. While getting enough vitamin D is important, it’s also important not to take too much in supplement form, which is dangerous. That can make shopping for the perfect vitamin D supplement tricky. Curious about how much vitamin D3 you should take daily? Here’s everything you need to know.What’s the difference between vitamin D2 and vitamin D3?Like all nutrients, Allison Miner, EdD, RDN, a registered dietitian and assistant professor of nutrition and food studies at George Mason University, says the best way to get vitamin D isn’t in supplement form; it’s through food and, in this case, the sun. She says that foods with vitamin D include fatty fish, egg yolks, and fortified cereals, orange juice, and milk. Also, apparently, beef liver.Sina Gallo, PhD, RD, a registered dietitian and nutritional sciences associate professor at the University of Georgia, explains that fatty fish, egg yolks, and beef liver all contain vitamin D3 while fortified foods contain both.“Some research has suggested D3 can raise and maintain blood vitamin D levels more effectively and for longer than D2, although if taken daily they likely act similarly. Both forms need to be converted to the active form, calcitriol, to have any biological activity in the body,” Dr. Gallo explains. This is why vitamin D3 supplements are often recommended over vitamin D2; vitamin D3 raises vitamin D levels more efficiently and keeps levels elevated for longer.When it comes to getting vitamin D from the sun, this is more complex. Dan Benardot, PhD, RD, FACSM, a registered dietitian and professor of practice at Emory University, explains that UV-beta rays from the sun create a compound called dehydrocholesterol. This compound is found in the skin and is then converted to vitamin D3.“This way of getting vitamin D is not a safe nor sustainable source of vitamin D because of its potential for skin cancer,” Dr. Gallo says. She adds that how much vitamin D3 someone gets from the sun varies based on where they live, the time of day they’re getting sun exposure, and their melanin content.Dr. Miner explains that the more melanin (the pigment that gives skin its color) someone has, the longer they have to be in the sun to experience the synthesis needed for producing and storing enough vitamin D. Someone who doesn’t have a lot of melanin (typically people with pale skin) needs less sun exposure.How much vitamin D3 to take, if you’re going to take a supplementAll four nutrition experts say that signs you’re not getting enough vitamin D can be pretty vague, such as fatigue, brain fog, and feeling depressed. That means that you can be deficient in vitamin D and not even realize it. Dr. Rodriguez says that this is dangerous because it leads to absorbing less calcium from food, which can lead to weak bones. She says that it can also lead to muscle weakness.According to all four experts, the only true way to know if you are deficient in vitamin D is through a blood test called 25-hydroxy vitamin D test. If your healthcare provider tells you that your blood work shows that you are not getting enough, then you can discuss with them if you can benefit from a supplement.As explained before, vitamin D3 is the preferred form of vitamin D in supplement form because it raises vitamin D levels in the body more efficiently. How much vitamin D3 should you take daily? “The general guidance for most healthy adults is between 600 and 800 international units a day, which is likely sufficient to prevent bone diseases. But some experts suggest higher amounts may be necessary to have any effects on non-bone health outcomes,” Dr. Gallo says. With this in mind, Dr. Benardot recommends taking a vitamin D3 supplement with roughly 1,500 international units.More vitamin D3 isn’t necessarily better. Dr. Benardot says that getting more than 5,000 international units of vitamin D3 a day is considered toxic. Dr. Rodriguez says that getting too much vitamin D is dangerous because it can cause calcium buildup in the arteries, which can negatively impact the cardiovascular system, including causing high blood pressure.Considering that the amount of melanin someone has impacts how much time they should spend in the sun to get enough vitamin D, you may be wondering if this means that people with different skin colors should take different amounts of a vitamin D3 supplement. The answer is no. Dr. Benardot explains that people with high melanin content (who tend to have darker skin) typically make less vitamin D from sun exposure, making them more likely to be deficient in vitamin D compared to people with low melanin, but this does not impact the recommended supplement dose.Even as we move into the sunniest part of the year, if you spend the majority of your time inside and are diligent about sunscreen, there’s a good chance that you could benefit from a vitamin D3 supplement. Get your bloodwork done to be sure and when choosing a vitamin D3 supplement, stick with one with a dosage of around 1,500 international units.With those guidelines in mind, you’ll safely have your vitamin D base covered without going overboard.