The Food and Nutrition Board (the ones that make the Dietary Reference Intakes) recommends 15 mcg (600 IU) of vitamin D per day for children and adults. They base this on what’s required to maintain bone health and regular calcium metabolism in healthy individuals. However, the recommended dietary allowance may be higher if you are over the age of 70. If you are deficient in Vitamin D, your doctor will likely recommend that you take a higher dose daily.
The Endocrine Society's recommendations differ slightly from those of the Food and Nutrition Board. They suggest an intake ranging between 37.5 to 50 mcg per day (equivalent to 1,500-2,000 IU) for all adults. Contrarily, the FDA's recommendation stands at 20 mcg, which is the same as 800 IU daily.
Vitamin D used to be dosed in “international units” (i.e. IUs), but the FDA has updated their unit of measure to mcg. The conversion is that one microgram is equivalent to 40 IU. However, you may see both units of measure on labels. You should speak with your doctor to determine the exact dose that is appropriate for you.
The severity of your vitamin D deficiency will determine how much vitamin D you need to take. Mild to moderate deficiency is considered 10-24 ng/mL and severe deficiency is anything below 10 ng/mL according to certain lab references however ranges may differ slightly based on lab being used. Therefore, you will need to check your blood levels and talk with your doctor about how much vitamin D you should supplement with for your specific needs. For severe deficiencies, doctors will often order a prescription dose of vitamin D of 1250 mcg (50,000 IU) to be taken once a week for several weeks. For less severe or moderate deficiencies, physicians will often recommend consistent supplementation for 2–3 months at a predetermined dose.
The requirements for vitamin D vary slightly depending on age. Here are the guidelines according to age:
It's important to keep in mind that these are general recommendations, and individual needs might vary based on specific conditions and circumstances.
Vitamin D is vital during pregnancy and breastfeeding because it supports the proper development of the baby's bones and immune system. It’s also necessary for ensuring the mother’s bone health and regulating calcium levels. Here are the recommended intakes:
Depending on individual health conditions, lifestyle, or specific needs, healthcare providers might suggest different dosages. It's always advisable for pregnant or breastfeeding women to consult with their doctor to determine the most appropriate Vitamin D intake for them.
Vitamin D is one of the most commonly recommended supplements. The rising incidence of vitamin D deficiency is attributed to several modern-day factors. Many of us now spend more time indoors, limiting our exposure to the sunlight that facilitates vitamin D production in our skin. Compounding this, few foods naturally contain vitamin D, and while sunscreen protects us from harmful UV rays, it also inhibits vitamin D synthesis. Those with darker skin pigmentation produce vitamin D less efficiently, and living in high latitudes further reduces sunlight exposure.
Vitamin D is an essential nutrient and a fat-soluble vitamin. It’s best known for its role in supporting strong and healthy bones by helping to regulate calcium metabolism in the body. Vitamin D is also well-researched for supporting immune health. You can get Vitamin D through some foods, but more commonly, your body synthesizes vitamin D through moderate exposure to sunlight. If you don't get a lot of direct sun (e.g. exposed skin without sunscreen for at least 15 minutes daily), or if your diet is low in foods containing vitamin D, supplementing may be a good option.
Bone health: Most of us don’t consider our bone health unless we have a reason to, but strong joints and bones are essential at every stage of life. From before we’re born to our older years, vitamin D plays a role in our evolving bone health. In utero, vitamin D helps support bone structure and tooth enamel development, which is why it’s often found in prenatal supplements. As children and adults, vitamin D is necessary for calcium and phosphorus absorption, both major components of bone health.
Immune health: Vitamin D plays a critical role in supporting a healthy immune system and is one of the most well-researched vitamins that support immune health. Several placebo-controlled studies have shown that vitamin D can regulate the growth and function of immune cells, which are responsible for strengthening our body's natural defense system. More specifically, vitamin D helps keep our immune system healthy by activating our T cells. T cells (AKA lymphocytes) form part of our adaptive immune system, constantly teaching it to recognize and react to foreign antigens. When T cells are exposed to an antigen, they search for vitamin D to activate their immune response process.
The best way to know if you have a vitamin D deficiency is to take a blood test. Most doctors include vitamin D screening as part of routine blood work. You can request your doctor to give you a 25-hydroxy vitamin D test (AKA 25(OH)D test), or you can get a home kit to test your vitamin D levels at home. The signs of vitamin D insufficiency are often hard to see. Some may experience:
These signs and symptoms are not specific to a vitamin D deficiency, so if you’re experiencing any of them, make sure to talk to your doctor. As mentioned earlier, there are also several factors that may increase the likelihood of a vitamin D deficiency, like age, mobility, location (distance from the equator), and digestive issues.
There are no golden rules for when to take vitamin D supplements. However, there may be certain times that are better than others. There is some evidence that suggests vitamin D is best absorbed when you take it with a meal that includes healthy fats (think avocados, fatty fish, and nuts), since vitamin D is a fat-soluble vitamin.
Ultimately, however, you should take vitamin D at a time of day when it is easiest for you to remember to take it. Many people prefer to take vitamins with breakfast as part of their morning routine to help them build consistent habits.
Although sunlight is the primary source of vitamin D, there are certain foods that can provide this essential nutrient. Fatty fish like cod liver oil, trout, salmon, tuna, and sardines are rich in vitamin D. Other sources include red meats, chicken breast, egg yolks, and mushrooms.
To address the common deficiency in the modern diet, many products such as breakfast cereals and dairy products are now fortified with vitamin D.
When choosing a vitamin D supplement, look for a high-quality product with transparent labeling so you know what you’re getting and where it comes from.
Vitamin D2 vs D3: There are two types of vitamin D: D2 (ergocalciferol) and D3 (cholecalciferol). We suggest supplementing with vitamin D3, a naturally occurring and more bioavailable form of vitamin D, which means it will be easier for your body to digest and absorb.
Consider the source: Natural supplement forms of vitamin D3 come from two sources. Vegetarian D3 is most commonly derived from sheep lanolin and vegan D3 can be derived from algae. Both are effective sources so consider your own preference and sustainability practices when deciding between the two.
Vitamin D, also referred to as the “sunshine vitamin,” is a necessary component for maintaining bone health and a healthy immune system. Supplementing with vitamin D is becoming more prevalent due to spending more time indoors and away from the sun. Recommendations for vitamin D can vary, but the general guideline is about 15 mcg (600 IU) per day. Consulting with your healthcare provider will give you the best guidance on determining whether you need a Vitamin D supplement and what the best dosage would be for you.