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 deficiency causes low levels of the mood-enhancing brain chemical serotonin, resulting in sadness and irritability


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

Because vitamin D plays a role in the production of bacteria-fighting proteins, its deficiency can cause immunity problems


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

Insufficient vitamin D intake can cause respiratory tract 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

A lack of vitamin D is likely to make muscles weak and increase the risk of injury and fall


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

Vitamin D deficiency can hamper calcium absorption, causing weak bones


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

A low vitamin D intake increases the risk of neurodegenerative diseases like Alzheimer’s and Parkinson’s


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