6 Health Problems Vitamin D Deficiency Can Cause

Vitamin D is a fat-soluble nutrient. Its biggest source is actually the sun as it helps the skin produce 50–90% of your vitamin D intake. Food sources like egg yolk, fortified dairy products, fatty fish, and beef liver offer small amounts of vitamin D too. As a steroid with hormone-like activity, vitamin D is crucial for growth and development.

Unfortunately, many of us are deficient in it. Over a billion people around the world don’t get enough vitamin D.¹ In the United States, 25% of the population is at risk of inadequacy while 8% is at risk of deficiency.² People who work indoors, wear excess clothing, and have darker skin tend to be at a higher risk for vitamin D deficiency.³

Here are 6 health problems insufficient vitamin D intake can cause.

1. Low Mood

Vitamin D is needed to convert tryptophan into serotonin, a brain chemical that regulates mood, decision making, and social behavior. Low levels of vitamin D mean low serotonin, which leads to feelings of sadness and depression.⁴ Vitamin D deficiency is the reason why seasonal affective disorder, or SAD, is so common during the dreary months of winter. Many people feel lethargic, drowsy, and the need to socially hibernate.⁵ In the case of SAD, vitamin D supplements can make up for the lack of sun.

2. Poor Immunity

Nutrients like vitamin C and zinc are often associated with the immune system. However, vitamin D can aid T-helper cells, making it a vital part of the team.⁶ A 2012 study in the Journal of Investigative Medicine also found that vitamin D helps white blood cells make more bacteria-fighting proteins.⁷ So, if you don’t consume enough vitamin D, you are likely to suffer from immunity problems.

3. Respiratory Infections

Adults and children with low vitamin D levels are known to suffer from frequent coughing and upper respiratory tract infections.⁸ With vitamin D’s immunity-boosting benefits, recurring episodes may be prevented. Moreover, research has even shown benefits of vitamin D for treating and preventing tuberculosis.⁹ So, insufficient vitamin D is likely to have damaging effects on your respiratory tract.

4. Muscle Weakness

Did you know that muscles contain vitamin D receptors? However, without enough of this nutrient, muscles can become weak. This, in turn, can lead to poor balance and physical function, increasing the risk of injuries and falls.¹⁰ For older adults who stay indoors, adequate vitamin D is especially important.

5. Bone Weakness

Calcium might be vital for healthy bones, but it can’t keep bones strong by itself. Vitamin D aids absorption and maintains homeostasis of the mineral, which explains why calcium supplements often have added vitamin D. A low intake of vitamin D can lead to weakness, brittle bones, and pain, especially in the lower back, low extremities, and pelvic area.^{11 12} Over time, vitamin D deficiency can severely increase the risk of osteoporosis, especially in postmenopausal women.¹³

6. Neurodegenerative Diseases

Low vitamin D levels result in a higher risk of poor memory and motor function, which are the primary symptoms in patients with Alzheimer’s and Parkinson’s.^{14 15} And while the exact relationship is unclear, it’s certainly worth noting.

Now that you know the health risks caused by vitamin D deficiency, it’s important to know how much your vitamin D intake should be.

How Much Is Enough?

For people from ages 1 to 70, including pregnant and breastfeeding women, the recommended intake is 600 IU. Adults who are 71 and older need 800 IU.

The upper limit is 4,000 IU a day. Any more than that may lead to toxicity and cause nausea, vomiting, weight loss, and kidney damage. Only take more than 4,000 IU if your doctor says so.¹⁶

To avoid vitamin D deficiency, spend 15 to 20 minutes in the sun each day. About 40% of your skin should be exposed. If you have dark skin, talk to your doctor for a personalized recommendation as melanin can slow down vitamin D production.¹⁷