Vitamin D is an important vitamin for overall health. You get vitamin D from the sun, foods you eat, or supplements. If you have too little, you may become weaker, feel extremely tired, have muscle or joint pain, and develop eczema, a skin rash. Long-term problems include depression and high blood pressure.
This article explains how D3 compares to other forms of vitamin D, the many benefits of vitamin D3, and how you can safely get more vitamin D by, specifically, increasing your intake of D3.
How Vitamin D Works
There are two forms of vitamin D:
- Vitamin D2 (ergocalciferol) is naturally found in some plants.
- Vitamin D3 (cholecalciferol) is naturally found in animals and is produced by the skin when it’s exposed to sunlight.
You can meet your requirements for vitamin D with both of these. To be used in the body, the vitamins first have to be processed in the liver and kidneys. While D2 and D3 are very similar, different enzymes, or proteins, are needed to activate each one and make them ready to use.
D3 works better than D2 to support the body and its functions.
- It raises your overall vitamin D level higher than D2.
- It lasts longer in the body than D2.
Thus, D3 goes farther and does more than D2. When doctors recommend vitamin D supplements, they’re likely to tell you to take D3 vitamins.
Once it’s activated, vitamin D attaches itself to cells in your body. The vitamin then helps control how much calcium and phosphate you absorb from food. Calcium is essential for bones, and phosphate is needed for healthy bones, teeth, muscles, nerves, and basic bodily functions.
Vitamin D3 offers many health benefits. It strengthens bones and muscles, boosts immunity, improves mood, reduces inflammation, and improves heart function.
Vitamin D works with calcium to support your bones. You need vitamin D to absorb calcium from the food you eat as it passes through the intestines. If you don’t have enough vitamin D, the body can’t get calcium from food so it takes calcium out of your bones. This leads to weaker bones, fractures, and osteoporosis.
Getting more D3 from foods is specifically helpful for improving peak bone density. Bone density is the maximum amount of bone tissue you reach during in adulthood.2 The better your bone density, the less likely you are to develop diseases that weaken bones.
Along with stronger bones, vitamin D seems to help you build stronger muscles. Studies have shown a connection between higher muscle strength and higher levels of vitamin D.3 In fact, researchers found that people with more vitamin D had leaner bodies, more muscle mass, and muscles that worked better.
Vitamin D may play an important role in protecting you from viruses and bacterial infections. Among the benefits, research shows it helps you fight acute respiratory infections and pneumonia.4
Having too little vitamin D may put you at risk for COVID-19. More research is needed, but some studies have found that you’re more likely to become infected and have a severe case of COVID if your vitamin D levels are low.
People with clinical depression often have vitamin D deficiencies.6 However, it’s not clear why this is. A lack of vitamin D could cause depression. On the other hand, changes in lifestyle due to depression (poor eating habits, little time outdoors, alcohol or drug use, etc.) could cause a drop in vitamin D.
Researchers have found evidence that raising vitamin D levels helps with symptoms of depression. Larger studies are needed to understand the connection better. With what they’ve seen so far, though, researchers are hopeful that vitamin D may eventually be used as part of a treatment for depression.
Several studies have shown that vitamin D has an impact on disease or disorders caused by inflammation.
Low vitamin D seems to lead to an increased chance of:7
- Atopy, an allergy-like condition you inherit
Studies have even shown that pregnant women who took vitamin D supplements were less likely to have a baby with asthma.8 However, you should talk to your doctor before taking any supplements during pregnancy.
A lack of vitamin D increases your chances of heart disease, stroke, blood pressure, and heart attacks.9
D3 seems to reduce the risk of heart failure by improving heart function in people who have weak heart muscles. More research is needed, but it may mean that D3 could be used as part of the treatment for heart failure patients.
Sources of D3
To increase your vitamin D levels, you can take supplements, get more sunlight, or eat more foods that have a lot of vitamin D3. It’s difficult to get enough D3 through diet alone, but eating more of the foods below can help.
Vitamin D is measured in IUs (international units). The Food and Drug Administration (FDA) recommends adults up to age 70 get 600 IU per day. Those over 70 should get 800 IU per day. In most cases, you can handle a maximum daily intake of 4,000 IU.
|Amount of D3 in Foods|
|Beef liver||42 per 3 ounces||5%|
|Butter||9 per tablespoon||1%|
|Cereal||80 per serving||10%|
|Cheese||12 per ounce||2%|
|Cod liver oil||1,360 per tablespoon||170%|
|Egg yolks||44 per yolk||6%|
|Fresh salmon||570 per 3 ounces||71%|
|Halibut||384 per half fillet||48%|
|Mackerel||360 per half fillet||45%|
|Milk (fortified)||120 per cup||15%|
|Sardines||46 per 2 fish||6%|
|Trout||645 per 3 ounces||81%|
|Tuna||40 per 3 ounces||5%|
If you’re vegetarian or a vegan, there may not be good sources here for you. Taking supplements may be more important for you. You can boost your vitamin D with foods that contain D2.
|Alternative Sources for Vitamin D2|
|FOOD||IU/SERVING||% DAILY VALUE*|
|Almond, oat, or soy milk (fortified)||100-144 per 1 cup||13%-18%|
|Mushrooms (portabella)||4 per 1/2 cup||1%|
Supplements are the easiest way to ensure you’re getting enough vitamin D3 every day. Studies show that supplements seem to be just as effective for boosting D3 as sunlight and food.
Talk to your doctor about D3 supplements before you begin taking them. Discuss the benefits and dosage that’s best for your needs.
When you’re ready to start a daily supplement, do your research to find high-quality products. The FDA doesn’t oversee supplements. To find trusted brands, look for “USP Verified” on the label. That means the U.S. Pharmacopeial Convention (a nonprofit scientific organization) has verified that:
- The ingredients and potencies listed on the label are accurate.
- The product doesn’t contain harmful levels of contaminants.
- Your body can absorb the supplement.
- The makers followed FDA guidelines and procedures.
When the ultraviolet B rays from the sun hit special vitamin-D receptor cells in your skin, they trigger a chemical reaction that produces vitamin D3. While getting a little sunlight every day can help you maintain your D3, it’s not the safest or most reliable way to stay healthy.
If you don’t go in the sun much, use sunscreen regularly, or have darker skin, you won’t meet your vitamin D needs from the Sun.
One concern is the fact that the sun’s rays increase your risk of cancer. Some experts recommend 10 to 15 minutes of unprotected exposure a few times a week in order to maintain vitamin D levels, but the Centers for Disease Control and Prevention and other medical authorities say there’s no safe way to get vitamin D from the sun without putting yourself at risk for skin cancer.
The second problem is that it’s hard to rely on sunlight, and you can’t measure how much vitamin D you’re making from the sun. It’s easier to keep track of the vitamin D in foods or supplements.
Research shows that over a billion people worldwide have a vitamin D deficiency. Symptoms and associated conditions include:
- Muscle weakness and aches
- Weak bones
- Hair loss
A simple blood test is used to measure your vitamin D levels. Your doctor can order this to be done as part of a regular check-up to see if you have too little vitamin D.
Vitamin D3 is generally safe. If you take too much vitamin D3, though, it can have toxic effects.
Too much vitamin D can cause you to absorb too much extra calcium. That can lead to a condition called hypercalcemia, which may weaken bones, interfere with your brain and heart, and cause kidney stones.
Some symptoms of vitamin D toxicity include:
- Muscle weakness
- Mood changes
- Loss of appetite
- Excessive urination
- Excessive thirst
Extremely high vitamin D3 levels can lead to:
- Kidney failure
- Irregular heartbeat
Toxicity problems are caused almost exclusively by taking too many vitamin D supplements. It’s difficult to take in that much from the food, and your body doesn’t produce that much vitamin D from sunlight.