|February 13, 2024

Benefits of Vitamin D and How to Get More of It

By Bulletproof Staff
Reviewed by Theresa Greenwell for Scientific Accuracy on 10/17/2023

Benefits of Vitamin D and How to Get More of It

  • As many as 75 percent of U.S. teens and adults are deficient in vitamin D.
  • Vitamin D supports your entire body. It’s essential for strong bones, muscular function and immunity, plus tons of other roles.
  • Your body naturally produces vitamin D from sunshine (that’s why it’s called the sunshine vitamin), but sometimes, it’s hard to get enough sunlight.
  • Certain foods, like fatty fish and eggs, have vitamin D. You can also take a vitamin D supplement to make sure you get your daily dose. Even better? Get vitamin D, plus vitamins A and K, in sugar-free Bulletproof Vitamins A+D+K Gummies.

Spending time in the sunshine doesn’t just feel good — it’s also an easy way to help your body naturally produce vitamin D, the sunshine vitamin. The problem is that as many as 75 percent of U.S. teens and adults suffer from vitamin D deficiency.[1] You need vitamin D. It supports strong bones, muscle function and immunity. Read on to learn about more about vitamin D benefits and how to make sure you’re getting your daily dose.

What is vitamin D?

Woman jogging on trail in sunshine

Vitamin D supports your entire body. It acts on thousands of different genes to support daily function, and it helps your body absorb calcium — the mineral that helps build strong bones.

There are two types of vitamin D: D2 (ergocalciferol) and D3 (cholecalciferol). D2 is made naturally by plants, and D3 is the form your body naturally produces when it’s exposed to sunlight.[2] If you’re looking at vitamin D supplements, you want D3. Because it’s the form your body naturally makes, D3 is more easily utilized by your system.

Good news: You get vitamin D3, plus added vitamins A and K, in Vitamins A+D+K Gummies: your one-stop-shop to support strong bones, strong heart and a strong immune system.

Science-backed benefits of vitamin D

Scientist holding out hand with gear in palm

Strong bones and teeth

Vitamin D is essential for calcium absorption and bone health. It plays a key role in bone mineralization and remodeling — aka the process your body uses to maintain strong bones and repair old bone tissue.[3] Your skeleton is kind of a big deal, and your body does a great job of maintaining its integrity. Vitamin D is a necessary part of that equation.[4]


To support strong muscles, make sure you’re getting adequate levels of vitamin D.[5] Vitamin D deficiency is associated with muscle weakness and impaired muscle function.[6] In fact, early rodent studies suggest that adequate vitamin D supports normal muscle size, strength and recovery. [7]


Your immune system is responsible for protecting your body against disease. Vitamin D helps regulate the cells in your immune system so they can do their jobs.[8]

Vitamin D optimal range

Odometer with red border around 100

According to the Mayo Clinic, the recommended daily amount of vitamin D is 600 IU (15 micrograms) for those between the ages of 1 to 70 years old.[9]

However, it’s tough to offer general guidelines for vitamin D. It largely depends on a variety of factors like your age, diet, skin color and location. In 2018, a Norwegian study found that a normal amount of vitamin D reduces the risk of death by 30 percent in people with cardiovascular disease.[10] But according to study lead Professor Jutta Dierkes at the University of Bergen, “The optimal amount of vitamin D supplement varies from one person to another. It depends where you live, and what kind of diet you have.”

For example, the standard recommendation for Nordic countries is 10 micrograms per day from all vitamin D sources. However, the U.S. recommends 15 micrograms, while Germany aims for 20 micrograms. “Even if Norwegians receive less sun then the Germans, the Norwegians have more fish in their diet. Fish and cod liver oil are important sources to vitamin D during the winter, in addition to physical activities outdoors during the summer,” notes Dierkes.

What does that mean? Even if you think you’re getting enough daily sunshine, you might not be hitting your recommended daily dose of vitamin D. The bottom line is that a lot of people can benefit from getting more vitamin D.

Why you’re low in vitamin D

Most of us are low in vitamin D because of the way we live — we cover our bodies, “protecting” every inch of our skin from the sun and stay inside most of the time. But instead of protecting your skin, you’re really just slowing or stopping your skin’s synthesis of vitamin D from the sun!

Supplementing with vitamin D3 is essential for most people to get their levels high enough, but that doesn’t mean you can stay out of the sun entirely. Your skin interacts with natural sunlight to produce vitamin D in your body.[11] Simply taking a ton of vitamin D is not the complete answer in the long run for preventing vitamin D deficiency. You want to attack the problem from all angles: with your diet, with sun exposure and with a supplement. Keep reading to learn how to support vitamin D production.

How to boost your vitamin D levels

Man and woman standing outside in the sun

It’s a good idea to talk to your doctor before you make any changes to your diet or lifestyle. Broadly speaking, here are some easy ways to effectively increase your vitamin D:


Here’s the easiest way to naturally boost vitamin D production: Aim for about 20 minutes a day of direct sun exposure. That’s it. Nature has you covered. As an added bonus, sunlight is a great way to support your circadian rhythm, and vitamin D production is associated with sleep quality — which means getting more sunlight is a fantastic way to make sure you’re getting great shut-eye.

However, depending on your schedule or where you live, it might be tough to get enough sun exposure. Keep reading for two more tips.


Vitamin D is added to fortified foods you can find at the grocery store, like milk, orange juice and cereal. But if you don’t tolerate dairy or want to avoid high-sugar cereal and fruit juice, add these foods to your diet instead:

  • Fatty fish like tuna, salmon and sardines
  • Egg yolks
  • Beef liver
  • Cod liver oil


Vitamin D supplements make it easy to make sure you’re hitting your daily dose of the sunshine vitamin, even when you aren’t getting any sun. Here are a few tips to keep in mind:

  • Opt for vitamin D3. Remember, D3 is more easily used by your body.
  • Take vitamin D3 with K2. These vitamins work together to transport calcium from the bloodstream into your bones, which supports bone density and heart health. Bulletproof Vitamin A-D-K also adds vitamin A, which works with D to support your immune system. That means you support your bones, heart and immune system with just one pill. And if you prefer gummy vitamins, go with sugar-free Vitamins A+D+K Gummies.

Sugar doesn’t belong in your vitamins. Get the details on the effects of sugar on the brain—and how to beat those sugar cravings.

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