vitamin d guideDiet & Nutrition

Vitamin D: A Guide to Foods and Supplements

Vitamin D. Do you ever wonder if you are getting enough of it, whether you should be taking a supplement, or why vitamin D is even important?

In this article, I will discuss everything you need to know about this essential nutrient and hormone—how to get it, what foods have it, and how to choose and take a vitamin D supplement if you need it.

Vitamin D: A Crucial Nutrient & Hormone

Vitamin D is both a nutrient we get through the foods we eat and a hormone our bodies make. It is a vitamin that helps your body absorb and retain calcium and phosphorus—two minerals that are critical for bone health. Vitamin D is also helpful in reducing inflammation and boosting immune function and cell growth.

It is recommended that the average person (someone without a vitamin D deficiency) get at least 600–800 international units (IU) of vitamin D everyday.

Getting Vitamin D Through Sunshine

Vitamin D is often referred to as the “sunshine vitamin” because it is produced within the body when the sun hits the skin. While it takes every person a different amount of time to make enough vitamin D to meet the body’s requirements, it is generally recommended that you get 10–15 minutes a day of direct sunshine on your bare forearms or lower legs.

Since excessive sun exposure carries its own risks, be sure to cover up or protect your skin with sunscreen if you plan on staying outside longer…before your skin starts to turn red or show signs of burning.

Unfortunately, during the winter months, the sunrays in most geographic areas aren’t powerful enough to help your body make enough vitamin D. Therefore, as a general rule, it is also important to get vitamin D through other sources, such as foods or supplements. In this article, I will discuss both.

Vitamin D FAQ

Question: Does getting sun through a window count as getting vitamin D?

Answer: No. In order for your body to make vitamin D, your skin needs to be directly exposed to sunlight. Your body cannot make vitamin D if you are sitting indoors by a sunny window because ultraviolet B (UVB) rays (the ones your body needs to make vitamin D) cannot get through the glass.

However, the other type of radiation—UVA rays—can get through a window, meaning that your skin will still tan and burn.

Actionable Takeaway

  1. Try to get 10–15 minutes of direct sunlight everyday on your forearms or legs.

Getting Vitamin D Through Foods

Not very many food sources are naturally rich in vitamin D. With that said, fatty fish and seafood are excellent sources of vitamin D. For example, one serving of salmon can provide up to 50% of the recommended daily dose of vitamin D. Other kinds of fish and seafood that are rich in vitamin D include tuna (both fresh and canned), mackerel, oysters, shrimp, sardines, and anchovies.

It is important to note that most of these fish are also excellent dietary sources of omega-3 fatty acids, a nutrient that has been shown to confer many health benefits, including the prevention of heart disease.

Other foods that are natural sources of vitamin D include egg yolks, liver, and mushrooms.

Fortified Foods

Fortified foods are foods that have been enriched with vitamins and nutrients. These nutrients do not normally occur in the product but are added during preparation. They are meant to help you boost vitamin and mineral intake. Most milk products and orange juice are fortified with vitamin D and calcium. Sometimes iron, fiber, zinc, and vitamin A are also added.

When shopping for food, a good habit is to glance at the nutritional labels. Just because a food product is fortified does not mean it is considered a healthy choice. For example, many types of yogurt and cereal are fortified with vitamin D, but they also frequently contain a good amount of added sugar. Margarine is another commonly fortified food, but some contain partially hydrogenated oils, an ingredient that is not considered healthy.

As a general rule, always aim to eat a variety of healthy foods from all of the food groups, including some fortified foods.

Actionable Takeaways

  1. Aim to eat 3 servings a week of a fatty fish, as these contain both vitamin D and beneficial omega-3 fatty acids.
  2. Start looking at food labels of fortified foods to check for added sugar and fat content.

Vitamin D Supplements: Do You Need One?

Certain groups of people are at risk for vitamin D deficiency. They are those who benefit from vitamin D supplements. In another article, I discuss the common signs and symptoms of vitamin D deficiency.

Ask yourself the following questions:

  • Are you 50 years or older?
  • Do you have darker skin?
  • Are you overweight or obese?
  • Are you on longterm steroids?
  • Do you have inflammatory bowel disease or a gluten sensitivity?
  • Do you have a milk allergy or follow a vegan diet?
  • Do you have chronic kidney disease?
  • Are you pregnant or breastfeeding?
  • Do you live in the northern United States or Canada (or anywhere far from the equator)?
  • Are you homebound or living in a nursing home or assisted living facility?
  • Do you spend most of your time indoors?
  • When you go outside, do you always avoid the sun by putting on sunscreen or by covering up?

If you answered yes to one or more of the above questions, you may be at risk for vitamin D deficiency and may benefit from a vitamin D supplement.

However, before you start taking any supplements, first ask your doctor about it. He or she will help you decide whether a vitamin D supplement is right for you. They may check your vitamin D level to see if you have a vitamin D deficiency. If you do have a deficiency, they will then work with you to make sure you are taking the right amount of supplement.

Actionable Takeaways

  1. Use the self-assessment questions to find out if you are at risk for a vitamin D deficiency.
  2. Discuss with your doctor whether you should start taking a vitamin D supplement.

Choosing a Vitamin D Supplement

D2 vs. D3: What’s the difference?

When shopping for vitamin D supplements, you may see two different forms: vitamin D2 and vitamin D3. Vitamin D2 is made from plants and is found in fortified foods and some supplements. Vitamin D3 is naturally produced in the human body and is found in animal foods.

Both forms increase vitamin D in your blood, but some studies have shown that D3 is slightly more effective at raising and maintaining vitamin D levels in your blood. Therefore, it is recommended that you choose vitamin D3 when looking for a supplement.

Finding Quality Supplements

vitamin d foods supplements guide usp verified

Do you ever wonder if one brand of vitamins is better than another? The unfortunate news is that since the U.S. Food and Drug Administration doesn’t oversee the quality of supplements, it can often be difficult to know if you are buying a good one.

Studies looking at the potency of various brands of available vitamin D supplements have found that brands can range widely in potency—from as low as 9% to as high as 146% of the expected dose!

The good news is that vitamin D supplements from USP-verified brands have been shown to be the most accurate and least unpredictable in terms of potency, so always take this into consideration and look for the USP mark when selecting a supplement.

Note: Vitamin D3 sometimes comes from animal sources. Therefore if you are vegan, look for D3 supplements marked as vegan or consider opting for D2.

Actionable Takeaways

  1. When shopping for a vitamin D supplement, choose D3 if you can.
  2. Buy a brand that has the USP-Verified stamp of approval.

Taking Vitamin D Supplements

How to Take Vitamin D Supplements

Vitamin D is a fat-soluble vitamin, meaning that it does not dissolve in water and is absorbed best in your bloodstream when paired with high-fat foods.

For this reason, it is recommended to take vitamin D supplements with a meal to enhance absorption. Avocados, nuts, seeds, full-fat dairy products, and eggs are nutritious sources of fats that help boost your vitamin D absorption.

Is It Possible to Get Too Much Vitamin D?

If you rely on diet and sunlight to reach your daily dose of vitamin D, you do not need to worry about getting too much, as your body is very good at regulating its production and balance.

However, there is a risk of getting too much vitamin D when you take vitamin D supplements.

When it comes to vitamins and supplements, more isn’t always better. Since vitamin D is fat-soluble, it is different from other vitamins (such as vitamin C or B), which your body can easily flush out if you get too much.

What this means is that if you take too much vitamin D supplements, the extra vitamin D actually gets stored inside your tissues and can accumulate to toxic levels over time—a condition called vitamin D toxicity, or hypervitaminosis D.

Vitamin D Toxicity: What to Know

As with all fat-soluble vitamin supplements (vitamins A, D, E, and K), it is important to be aware of the symptoms of vitamin toxicity. This is because toxicity can arise insidiously as the vitamin slowly accumulates in your body over time.

While vitamin D toxicity is more common with high doses of supplements (more than 10,000 IU per day), it can sometimes occur with doses as low as 4,000 IU when taken daily over a long period of time. While it used to be believed that vitamin D toxicity was extremely rare, studies now show that it is becoming more and more common. This is why it is important to coordinate with your doctor to ensure that you are taking just the right amount.

Signs and Symptoms of Vitamin D Toxicity

  • fatigue and sleepiness
  • muscle weakness
  • loss of appetite
  • nausea and vomiting
  • excessive thirst
  • constipation
  • irritability or nervousness
  • ringing in the ears (called tinnitus)
  • dizziness
  • confusion or disorientation

If you find yourself experiencing a number of these symptoms and you are taking vitamin D supplements, call a health care professional as soon as you can.

Vitamin D FAQ

Question: Do common medications interact with vitamin D supplements?

Answer: Yes. Some common prescription and over-the-counter medications can actually make it easier for you to get too much vitamin D. For example, some medications used to treat high blood pressure and heart diseases can cause an increase in vitamin D in the blood. Estrogen therapy and even regular antacid use can cause elevated levels of vitamin D.

If you do take a lot of medications, be sure to coordinate with your doctor to make sure that your supplement regimen is optimized. 

Actionable Takeaways

  1. Take your vitamin D supplement with fatty foods for maximum effectiveness.
  2. Make a note to discuss your supplement regimen with your doctor so that they can ensure you stay safe, healthy, and happy!

Phoebe Chi, MD
Phoebe Chi, MD

As a physician educator and the managing editor of Health + Inspiration, Dr. Chi aims to inform, empower, and inspire the reader community. She is the author of Being Empowered for a Healthy Heart: A personal guide to taking control of your health while living with chronic conditions, a poetry-infused health guide, and founder of Pendants for a Cause, a nonprofit organization with the purpose of raising funds to fight illness, provide care, and bring awareness to medically vulnerable populations around the world.

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