Vitamin D Supplement Benefits, Dosage and Side Effects - Dr. Axe

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Best Vitamin D Supplement Benefits & How to Choose the Right One


Vitamin D supplement - Dr. Axe

Vitamin D stands out from other micronutrients because it’s one of the few vitamins that your body is able to produce all on its own.  Also known as the “sunshine vitamin,” your skin is actually able to synthesize vitamin D when exposed to sunlight.

That being said, unfortunately many of us are lacking in this key nutrient, resulting in vitamin D deficiency. Because it’s found in very few food sources, coupled with the fact that most people don’t spend a lot of time in the sun each day, it’s often necessary to take a vitamin D supplement to help meet your daily needs.

So do vitamin D supplements work? Do you actually need one, and what is the best vitamin D supplement?

Here’s what you need to know…

Why You Need Vitamin D

Vitamin D is vital to several different aspects of health. Although it’s most well-known for its ability to strengthen the bones and boost calcium absorption, it’s also involved in immune function, disease prevention, mood regulation and weight control.


In fact, a deficiency in this crucial vitamin can cause issues like hair loss, chronic pain, sluggishness and decreased wound healing. It can even increase the risk for cardiovascular disease, diabetes and serious infections.

Unfortunately, vitamin D is found in very few food sources naturally, which can make it difficult to meet your needs through diet alone. Not only that, but many are also at a higher risk of vitamin D deficiency, including older adults, overweight individuals and those living in northern latitudes.

Taking a vitamin D supplement is an easy and effective way to ensure you’re able to meet your needs with minimal risk of adverse side effects.

Plus, in addition to effectively preventing a deficiency, vitamin D supplementation has also been linked to a number of different health benefits, as explained more below.

Vitamin D Supplement Benefits

Boosting your intake of this vitamin via supplementation can contribute to benefits, such as:

  • Support for bone health, including by assisting in calcium absorption
  • Supporting a healthy body weight
  • Boosting immune function
  • Improving your mood
  • Possibly helping to protect against cancer
  • And more

1. Supports Bone Health

Vitamin D plays an integral role in bone metabolism. In addition to increasing calcium absorption, vitamin D is also involved in the metabolism of phosphorus, another key mineral that supports bone health.

According to one study in the Journal of Mid-life Nutrition, low levels of vitamin D were associated with decreased bone mineral density in women. For this reason, taking a vitamin D and calcium supplement is often recommended for those at risk for bone loss, including postmenopausal women.

2. Enhances Immunity

If you find yourself feeling under the weather more often than usual, you may want to consider adding a natural vitamin D supplement into your routine.

Vitamin D is important for the function of immune cells, and increased susceptibility to infection is one of the hallmark signs of deficiency. One study published in the Archives of Internal Medicine found that low levels of vitamin D were linked to a higher risk of upper respiratory infections, such as the cold or flu.

3. Helps Prevent Deficiency

Taking a vitamin D supplement is one of the easiest and most effective ways to prevent a vitamin D deficiency.

Unfortunately, vitamin D deficiencies are incredibly common, especially among older adults, those with darker skin and those with limited sun exposure. Some of the most common symptoms of deficiency include fatigue, impaired wound healing, muscle pain and hair loss.

4. May Help Protect Against Cancer

Interestingly enough, some studies have found that getting enough vitamin D could aid in the prevention of certain types of cancer. In particular, vitamin D deficiency is thought to be associated with a higher risk of colon, breast, ovarian and prostate cancer.

According to a massive review in the American Journal of Public Health, “evidence suggests that efforts to improve vitamin D status, for example by vitamin D supplementation, could reduce cancer incidence and mortality at low cost, with few or no adverse effects.”

However, keep in mind that more research is needed to evaluate whether other factors may also contribute to the relationship between vitamin D levels and cancer risk.

5. Boosts Weight Loss

Not only do studies show that vitamin D levels tend to be lower in individuals who are overweight or obese, but some research also indicates that vitamin D supplementation could help bump up weight loss.


A study in the American Journal of Clinical Nutrition actually found that taking a calcium and vitamin D supplement resulted in significant reductions in body weight and fat mass compared to a control group. Another study showed that having adequate levels of serum vitamin D was associated with increased weight loss and fat loss in 218 women.

6. Improves Mood

Vitamin D can have a powerful impact on mood and may even aid in the prevention of conditions like depression. For example, a study conducted by the Institute of Clinical Medicine in Norway showed that supplementation with vitamin D significantly improved symptoms of depression in 441 adults.

What’s more, another 2017 study found that vitamin D was effective at improving mental health status and reducing depression and anxiety in women.

Best Vitamin D Supplement Options

With all the vitamin D supplements on the market, it can feel overwhelming trying to select one that’s right for you. What is the best vitamin D supplement to take?

Vitamin D2 and D3 are the two most common forms of vitamin D, found in both food sources and supplements. D3 is thought to be much more absorbable and therefore the best option. In fact, one study found that taking vitamin D3 was nearly twice as effective at increasing serum vitamin D levels than vitamin D2.

Ideally, look for a vitamin D supplement that contains vitamin D3, also known as cholecalciferol.

D3 from animal products (specifically from the cholesterol within these products) is closest to what sunlight naturally produces in humans when the skin works to convert UV light. Vitamin D3 is therefore the more active form and thought to be converted a lot faster than D2.

Additionally, check the ingredients label, and select a product with minimal added ingredients or fillers to ensure you get the best value for your money.

Specialty formulas are also available, such as those that combine vitamin D with calcium to help with absorption. Additionally, if you’re vegan, look for a vitamin D supplement that is specifically labeled as vegan.

Keep in mind that vitamin D is a fat-soluble vitamin, so if your supplement doesn’t contain an oil, you should take your vitamin D with a meal that contains a good source of fat to optimize absorption. A few slices of avocado, a handful of nuts or a square of dark chocolate can all help boost nutrient absorption.

Vitamin D Supplement Dosage and Uses

So how much vitamin D should you take a day? Is it better to take vitamin D at night or in the morning, and can you take vitamin D on an empty stomach?

The recommended dietary allowance (RDA) for vitamin D varies based on age. The current guidelines for vitamin D needs are as follows:

  • 400 international units (IU): infants 0–12 months
  • 600 IU: children and adults 1–70 years, including women who are pregnant or breastfeeding
  • 800 IU: adults over 70 years

Oftentimes, the vitamin D supplement dose can exceed the RDA, and many recommend using a vitamin D supplement with 5,000 IU or more to ensure adequate blood levels. However, while taking a vitamin D supplement dose below 10,000 IU per day is unlikely to yield any symptoms of toxicity, taking high doses may negatively impact health over time.

Note that, although breast milk and formula both provide a small amount of vitamin D, the American Academy of Pediatrics recommends the use of a vitamin D supplement for infants who are breastfed or consuming less than one liter of formula per day. Administering a vitamin D supplement for babies can help prevent deficiency while also reducing the risk of conditions like rickets.

Although there’s limited research on whether taking vitamin D at night or in the morning is more effective, taking it with a meal is key to promoting proper absorption. In fact, one 2015 study showed that taking vitamin D alongside a high-fat meal increased vitamin D levels 32 percent more than with a fat-free meal.

Who Should Take Vitamin D Supplements?

Vitamin D deficiency is one of the most common nutritional deficiencies around the globe. Which populations are especially at risk?

Older adults, vegans/vegetarians, and those who get limited sun exposure, have darker skin or are overweight are at a higher risk for vitamin D deficiency. People who live in northern latitudes may also be at an increased risk since they lack sun exposure.

If you suspect that you may have a vitamin D deficiency, it’s best to talk to your doctor and get your vitamin D blood levels tested to determine if supplementation is right for you. Your doctor can also help determine whether you need daily tablets or high-dose supplementation to help bring your levels up within the normal range.

Risks and Side Effects

Although there are many benefits associated with vitamin D, there are some vitamin D supplement side effects to consider as well.

For starters, taking very high doses over long periods of time can cause vitamin D toxicity, which can result in symptoms like drowsiness, stomach pain, vomiting and confusion.

For this reason, it’s important to stick to the recommended dosage and use supplements only as directed. If you experience any negative side effects as a result of vitamin D supplementation, consider decreasing your intake and talking to a trusted health care professional.

If you have any underlying conditions, such as high levels of calcium, hyperparathyroidism or kidney disease, it’s best to talk to your doctor before starting supplementation.

Vitamin D can increase calcium absorption, which could worsen issues related to these conditions. You may also want to consult with your doctor if you take medications such as diuretics, antacids, or heart medications like digoxin, diltiazem or verapamil.

Related: Can You Take Too Much Vitamin D?


  • Vitamin D supplements are often recommended for most babies, children and adults because deficiency in this vitamin is believed to be very common. That’s because many people today don’t spend enough time in the sun due to factors like working indoors or wearing sunblock.
  • While supplements are necessary and beneficial in many cases, it’s ideal to get the amount of D vitamin you need directly from sunlight if possible.
  • When choosing a supplement, opt for D3 instead of D2, which is absorbed better. Take your daily vitamin D supplement with a meal, specifically one containing a bit of fat.

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