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 fat-soluble vitamin that has long been known to help the body absorb and retain calcium and phosphorus; both are critical for building bone. Vitamin D is also helpful in reducing inflammation and boosting immune function and cell growth. It is recommended that the average person 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 (without sunscreen). 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 in many geographic regions, sunlight doesn’t contain enough UVB radiation for your skin to be able to make enough vitamin D. To see how your particular region does throughout the year, refer to the “Sunshine Calendar” (click image to enlarge). As you can see from the Sunshine Calendar, depending on whether you have light or dark skin tone, the amount of time needed in the sun to produce vitamin D is variable. Therefore, for many people, it is also important to get vitamin D through other sources, such as through foods or supplements. In this article, I will discuss both.
Vitamin D FAQ: “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’re 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—UVA rays—can get through, meaning that your skin will still tan and burn.
- Try to get 10-15 minutes of direct sunlight everyday on your forearms or legs.
- Check the Sunshine Calendar to see if your geographic region allows you to get enough UVB rays at different times of the year.
Getting Vitamin D through Foods
Not very many food items are naturally rich in vitamin D. With that said, fatty fish and seafood are excellent sources of vitamin D. A 3.5-ounce (100-gram) serving of salmon can provide up to 386 IU of vitamin D — about 50% of the recommended daily intake. Other kinds of fish and seafood that are rich in vitamin D include tuna (both fresh and canned), mackerel, oysters, shrimp, sardines, and anchovies.
Other foods that are natural sources of vitamin D include egg yolks, liver, and mushrooms.
Fortified foods are meant to help you boost vitamin and mineral intake. They are designed to add nutrients that don’t naturally occur in the product. Sometimes iron, fiber, zinc, or vitamin A is added. Most milk products and orange juice are fortified with vitamin D and calcium.
When shopping, be sure to glance at the food labels as some fortified foods contain added ingredients that actually make the product less healthy, such as added sugar or hydrogenated fats. 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, which are not considered healthy and should be avoided.
Therefore, always aim to eat a variety of healthy foods from all of the food groups, including some fortified foods.
- Aim to eat 3 servings a week of a fatty fish, as these contain both vitamin D and omega-3 fatty acids that benefit your health.
- 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 the ones that benefit from vitamin D supplements. To find out if you may be at risk, start by asking yourself the following questions:
- Are you 50 years or older?
- Do you have darker skin?
- Are you overweight or obese?
- Are you on long-term 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 U.S. or Canada (or anywhere far from the equator)?
- Are you home-bound or live 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 are likely at risk for vitamin D deficiency and may benefit from a vitamin D supplement. If you are not sure if you’re at risk, simply make a note to ask your doctor on your next visit. He or she may want to check your vitamin D level to see if you have a vitamin D deficiency. They should work with you to make sure you’re taking the right amount of supplement.
Vitamin D FAQ: “I spend more time indoors now because of COVID-19. Would I benefit from a vitamin D supplement?”
Answer: Yes, most likely. Actually, in light of the coronavirus pandemic where people in general are spending more time indoors, many physicians are now recommending that people take 400 IU (10 micrograms) of Vitamin D daily between the months of October and March. However, to be safe, always ask your personal health care professional before starting a new supplement.
- Use the self-assessment questions to find out if you are at risk for vitamin D deficiency.
- 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 show 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
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’re 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 variable 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.
- When shopping for a vitamin D supplement, choose D3 if you can.
- Buy a brand that has the USP-Verified stamp of approval.
Taking Vitamin D Supplements
How Much Should You Take?
It is recommended that the average person without a deficiency get at least 600-800 IU of vitamin D a day. Therefore, 600-800 IU is generally considered a safe dose for those wanting to take a supplement. Of course, given your personal health needs, your doctor may prescribe a much higher dose. But unless you are advised to do so by a physician, never take more than 4,000 IU a day to avoid the risk of vitamin D toxicity.
If you already take a multivitamin, be sure to look at the amount of vitamin D in it. You may not need to take additional vitamin D if you’re getting enough from your multivitamin.
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 fat 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. Rather, the risk comes when you start taking 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 water-soluble vitamins (such as vitamins C or B complex) in which your body can easily ‘flush out’ any unneeded excess. 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 more than 10,000 IU per day taken over several months, its symptoms have been seen in people taking as little as 4,000 IU a day. 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, ideally, you never want to exceed 4,000 IU per day…unless prescribed and monitored by a physician.
The main consequence of vitamin D toxicity is a buildup of calcium in your blood (hypercalcemia), which can cause a variety of symptoms, including:
- fatigue and sleepiness
- muscle weakness
- loss of appetite
- excessive thirst
- irritability, nervousness
- ringing in the ear (tinnitus)
- confusion, disorientation
If find yourself experiencing any of these symptoms, call a health care professional as soon as you can.
Vitamin D FAQ: “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 antacids 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 everything is all good.
Some Final Takeaways
- A safe vitamin D supplement dose to take is 600 IU a day.
- If your doctor prescribes a specific vitamin D supplement dose and regimen, always follow their instructions.
- Take your vitamin D supplement with fatty foods for maximum effectiveness.
- Vitamin D is fat-soluble, meaning that it can accumulate in your body tissues over time to harmful levels.
- Always coordinate with your doctor, so they can make sure that you stay safe, healthy, and happy!
*You can find more essential health information like this in Being Empowered for a Healthy Heart: A personal guide to taking control of your health while living with chronic conditions, by Phoebe Chi, MD, MPH.