What is Vitamin D and Why Does It Matter?
Vitamin D is sometimes referred to as the “sunshine vitamin,” but it’s really more like a hormone that your body produces when your skin is exposed to the sun. Everyone knows it supports strong bones and teeth, but its uses extend way beyond. Vitamin D assists your body in absorbing essential minerals such as calcium and phosphorus, maintains your immune system, and even has a role in the functioning of your brain and muscles.
How Your Body Obtains Vitamin D
The primary source through which your body obtains vitamin D is sun exposure. When your skin is exposed to direct sunlight, it initiates the process of vitamin D production. But that is not all. You can also obtain it from some foods—fatty fish like salmon, mackerel, and sardines are excellent sources. Other foods are also vitamin D-fortified, such as milk, cereals, and even certain mushrooms. There are also supplements available, particularly for those who don’t see much sun or eat vitamin D-rich foods.
There are some things that can influence how much vitamin D your body produces from the sun. The season, time of day, location, skin color, and even the amount of sunscreen you use all impact things. Those with darker skin, people who spend a lot of time indoors, or who live where there are long winters tend not to produce enough vitamin D from exposure to the sun alone.
Who’s at Risk for Vitamin D Deficiency
Vitamin D deficiency is more prevalent than most people know. It affects approximately a billion people worldwide, and in the U.S, around a third of adults are deficient. Some are more risk-prone than others. This includes older people, darker-skinned people, obese and overweight people, breastfed infants (particularly if the mother is vitamin D deficient), and anyone with conditions that impair the ability to absorb fat, such as Crohn’s disease or ulcerative colitis. If you reside in an area with limited sunlight or expose much of your skin for cultural or medical reasons, your risk increases as well.
Signs and Effects of Low Vitamin D
At first, vitamin D deficiency can be subtle. You may get tired more easily than before, experience muscle weakness, or have frequent cramps. In severe cases, it causes pain in bones and an increased risk of fractures. In children, low vitamin D can lead to rickets, which causes bones to be soft and even bowlegs. In adults, it can result in a condition known as osteomalacia, which softens bones, and it can also lead to osteoporosis.
Low vitamin D may also influence how you feel emotionally. Some studies have associated it with mood problems such as depression and anxiety. Individuals with long-term pain conditions such as fibromyalgia also tend to feel worse if their vitamin D status is low.
The Benefits of Vitamin D Beyond Bones
We all tend to associate vitamin D with bone health, but it does much more than that. It’s an important part of maintaining your immune system in balance and functioning as it should. Research suggests it might even lower the risk for autoimmune disorders such as psoriasis and multiple sclerosis. There’s also increased interest in whether vitamin D can help with mental health, particularly in people who are already experiencing low levels.
Scientists are investigating whether vitamin D can assist with heart health, ward off cancer, and even assist with weight loss. Although preliminary findings are encouraging in certain aspects, taking more than necessary won’t automatically provide you with additional benefits.
How Much Vitamin D Do You Need
The daily vitamin D amount recommended varies by age. Infants from birth to 12 months require 400 IU (international units) a day. For ages 1-70, the intake increases up to 600 IU. Past age 70, it’s 800 IU per day. Others prescribe 1,000 to 2,000 IU a day during periods of low sunlight exposure, such as winter. But don’t overdo it—more than 4,000 IU per day can be toxic.
Getting Vitamin D Safely: Food, Sun, and Supplements
The best approach to obtain sufficient vitamin D is by a combination of sun, diet, and supplements if necessary. It may be sufficient for some individuals to spend 15 minutes outdoors several times a week, but yet again, where you are located and the color of your skin make a difference. Taking foods that are high in vitamin D, such as fatty fish, fortified milk and cereal, or mushrooms that have been exposed to UV light, can also be beneficial. If you don’t know if you’re getting enough, a blood test can measure your level, and your physician can advise you on whether or not you need a supplement and how much.
The Risks of Too Much Vitamin D
Vitamin D is generally safe when one takes it in the recommended doses, but more doesn’t always mean better. Taking more than 4,000 IU daily consistently may cause issues such as nausea, vomiting, weakness, confusion, abnormal heart rhythm, and kidney stones or damage. High doses may also interact with medications such as those for heart disease, high blood pressure, and cholesterol. It’s for this reason that one should consult with one’s physician before taking high-dose supplements.
Vitamin D and Certain Health Conditions
For some health problems, having sufficient vitamin D is particularly crucial. It’s an integral component of the treatment of inherited bone diseases, rickets, and osteomalacia. In individuals with osteoporosis, ensuring you have sufficient vitamin D and calcium can decelerate bone loss and decrease fracture risks. Some studies indicate that long-term vitamin D intake might lower the risk of multiple sclerosis, but more research is necessary.
When it comes to heart health, large-scale studies demonstrate that taking high levels of vitamin D doesn’t appear to reduce the risk of heart attacks or strokes any more than moderate levels. The takeaway: get away from deficiency, but beyond that, taking more won’t provide additional protection.
The Future of Vitamin D Research
Researchers continue to learn about how vitamin D functions in the body and who benefits the most from supplements. There is interest in whether it will benefit autoimmune diseases, some cancers, and even how the body fights off infections such as COVID-19. Researchers are also exploring how your specific factors—such as your genes or your ability to absorb nutrients—impact your vitamin D requirements. In the future, we can look forward to more tailored recommendations based on your health profile.