Vitamin D: Benefits, Food Sources, Deficiency Signs and Daily Recommendations

What is vitamin D?

Vitamin D is a fat-soluble vitamin, which means it’s best absorbed by your body when taken with a meal or snack that includes some fat. It’s found naturally in some foods. Vitamin D is available over-the-counter as a supplement, and it’s also added to some foods such as cereals and orange juice. Your body makes vitamin D with direct sun exposure on your skin.

Vitamin D is an important nutrient for your body, as it helps the body absorb and maintain calcium, which is essential for bone formation and strength. Not having enough vitamin D can weaken bones, leading to rickets in children and osteomalacia in adults. Vitamin D, along with calcium, helps protect aging adults from osteoporosis, a condition that weakens bones and leads to fractures.  

What foods provide vitamin D naturally?

There are few foods that naturally have vitamin D, including:

• Fatty fish such as trout, salmon or tuna
• Sardines
• Herring
• Fish liver oils
• Beef liver
• Egg yolks
• Mushrooms 

What foods have added vitamin D?

Check labels, because many foods are fortified with vitamin D, including:

• Milk (cow’s milk, almond, soy and other plant-based milks)
• Yogurt
• Cereal
• Orange juice
• Tofu

→ See related: Newly Approved Sunscreen Ingredient Promises ‘Broad, Reliable’ Protection

What are symptoms of vitamin D deficiency?

In children, vitamin D deficiency is rare. Mild deficiency in children may result in sore or weak muscles or they may not have symptoms. Serious vitamin D deficiency can result in rickets, which can cause bones to grow incorrectly (bowed or bent bones) and joint deformity.

Adults with vitamin D deficiency may have no symptoms but may experience:

• Bone pain
• Muscle weakness or cramps
• Fatigue and tiredness
• “Pins and needles” sensations in hands or feet
• Changes in mood, such as depression 

How can I know if I’m deficient in vitamin D?

Vitamin D deficiency is diagnosed through a blood test. Certain groups of people may be more likely to be vitamin D deficient, including:

• Breastfed infants
• Older adults
• People with dark skin
• People with conditions that block nutritional absorption, such as celiac disease and ulcerative colitis
• People with obesity and people who have had gastric bypass surgery
• People with chronic kidney or liver disease
• People without exposure to sunlight (live in northern latitudes, work nights or wear sunblock
• Some medications can lower vitamin D levels, such as anti-seizure, cholesterol and steroids

How do I know if I’m getting enough vitamin D?

You can get vitamin D from three sources: sunshine, food and supplements. If you suspect you are having symptoms of vitamin D deficiency or if you belong to groups of people who are more likely to be deficient, you can ask your health care provider to order a blood test to check.

Do I need a vitamin D supplement?

Daily intake for adults from all vitamin D sources (food, beverages and supplements) is 15–20 mcg (600–800 IU). Adults who do not meet 600-800 IU daily may consider a supplement. People with certain bone disorders or conditions that affect vitamin D or calcium absorption may need higher doses, but those should be taken only under a medical provider’s guidance. Unless your healthcare provider recommends otherwise, avoid exceeding 100 mcg (4,000 IU) daily from combined sources of food, beverages and supplements, which is considered the safe upper limit for most adults. Infants that are formula fed with intake of less than 32 oz per day or who are breast fed/partially breast fed should supplement with a liquid vitamin D supplement of 400 IU/day. This should start soon after birth. As babies get older and can consume foods with vitamin D, supplements are no longer needed.

Are there side effects for taking too much vitamin D?

Taking too much vitamin D is possible and can result in vitamin D toxicity – a rare but serious condition that can result from taking too much vitamin D through supplements. Excess vitamin D can cause calcium to build up in the blood, leading to symptoms such as nausea, vomiting, weakness, frequent urination, kidney stones and bone pain. To reduce the risk of vitamin D toxicity, most adults should not take more than 100 mcg (4,000 IU) of vitamin D per day from all sources, unless directed by a healthcare provider.

When should I see a healthcare provider?

Consider talking with your health care provider about vitamin D if you have limited sun exposure. You may also want to ask about your vitamin D status if you have gastrointestinal, liver or kidney disease, which can contribute to low levels. Diet alone may not be enough to correct a vitamin D deficiency, so talk to your health care provider to determine whether blood work and supplementation are appropriate for you.

Key points: 

• Vitamin D helps your body absorb calcium and maintain strong bones.

• Your body produces vitamin D when skin is exposed to sunlight.

• Vitamin D deficiency can cause bone and muscle problems.

• Some people may need supplements to maintain healthy levels and should see their healthcare provider.

Sources:

• American Academy of Pediatrics Publications
• Vitamin D for Babies: Are Supplements Needed?
• Vitamin D Fact Sheet For Health Professionals - National Institutes of Health
• Vitamin D Fact Sheet For Consumers - National Institutes of Health
• Association Between Vitamin D Supplementation and Cancer Incidence and Mortality - Critical Reviews in Food Science and Nutrition 

The information provided is for informational purposes only and is not intended as medical advice. Please consult your doctor or another qualified healthcare professional for guidance about your specific health needs.