Take a look in your fridge, and you may find a bottle of orange juice or soy milk with a label that proudly declares it’s “fortified with vitamin D.” But why is this fact so important to call out in the packaging? The reason for the labeling is, vitamin D is an important nutrient that plays a role in keeping our bones and immune system strong. Unfortunately, many people, including those living with HIV, may have lower-than-ideal levels of this essential vitamin.

In this article, we’ll explore the role of vitamin D in our health and its relationship with HIV. While you read this, keep in mind that just because studies have found associations between HIV and vitamin D deficiency, this does not mean that HIV infection directly causes this deficiency or that raising your vitamin D levels will improve your HIV symptoms. Read on to learn more about vitamin D.

Vitamin D Is an Important Nutrient Our Bodies Need

There are several ways vitamin D assists the body, including:

• Building strong bones, by helping your body absorb and use calcium
• Supporting your immune system, which helps your body fight infections
• Keeping cells healthy by supporting cell growth and activity

Sources of Vitamin D

You may have heard vitamin D called the “sunshine vitamin,” based on the fact that a substance in your skin called 7-dehydrocholesterol is transformed into vitamin D when it’s exposed to sunlight — specifically ultraviolet (UV) light B. The amount of vitamin D your body makes depends on how much sun you get and your skin color.

Additionally, certain foods serve as good sources of vitamin D, including:

• Fatty fish, such as salmon, mackerel, and tuna
• Fortified foods, including cow’s milk, plant-based milk, orange juice, and breakfast cereal
• Egg yolks

What’s the Right Amount of Vitamin D?

A doctor can measure your vitamin D levels using a blood test. While individual levels vary, a blood vitamin D concentration of 50 to 125 nanomoles per liter (or 20 to 50 nanograms per milliliter) is considered to be the “normal” range.

Health experts recommend that people between the ages of 1 and 70 should aim to have 600 international units (IU) of vitamin D per day. People over 70 should aim for 800 IU. Getting too little or too much can lead to either vitamin D deficiency or toxicity.

Vitamin D Deficiency

Also known as vitamin D insufficiency, vitamin D deficiency is when you have too little vitamin D in your body. This can cause osteoporosis (thinning of your bones) as well as muscle weakness and cramping. Low vitamin D can also make you more vulnerable to infectious diseases and illnesses due to a compromised immune system.

Some groups of people have an increased risk of developing a vitamin D deficiency. If you have darker skin, the melanin pigment in your skin may block the sun’s rays and interfere with making vitamin D from sun exposure. Likewise, people who wear clothing that covers much of their body — such as dresses, robes, or head coverings — or who spend most of the time inside have an increased risk of vitamin D deficiency, because UV rays are needed to make vitamin D.

Older people may have low vitamin D levels because as we age, our bodies may not produce as much vitamin D when exposed to sunlight. Additionally, older adults often spend more time indoors, further reducing their sun exposure.

People who have trouble digesting fat, like those with ulcerative colitis, Crohn’s disease, or celiac disease, are also more likely to have vitamin D deficiency. Vitamin D is fat-soluble, meaning it dissolves in fat. For your body to absorb vitamin D from food, it needs to be able to digest and absorb fat.

Finally, people with obesity or who’ve had gastric bypass surgery may be at higher risk for vitamin D deficiency. Fat under the skin traps vitamin D, so the more you have, the more vitamin D is needed from your diet to maintain normal levels. In gastric bypass surgery, the part of the small intestine where vitamin D is absorbed is bypassed, limiting what vitamin D can be gained from your diet.

Vitamin D Toxicity

Elevated levels of vitamin D can also be harmful and can cause vitamin D toxicity (called hypervitaminosis D). When this happens, your body builds up too much calcium in your blood. In the short term, this can cause nausea, increased thirst, kidney stones, and weakness. Having vitamin D levels that are too high for a long time can lead to kidney and heart problems.

Vitamin D Deficiency and HIV

According to a 2018 study, nearly 30 percent of the U.S. population has a vitamin D deficiency. In people with HIV, the prevalence of vitamin D deficiency is significantly higher — between 70.3 percent and 83.7 percent.

Causes of Vitamin D Deficiency in People With HIV

People with HIV may develop vitamin D deficiency for the same reasons as the general population, but several HIV-specific risk factors may also contribute.

Chronic inflammation associated with HIV infection may play a role in decreasing the amount of the active form of vitamin D in the body. Complications and hospitalization from infections may lead to decreased exposure to sunlight and malnutrition from a lack of food that is rich in vitamin D.

A few studies have even linked certain HIV antiretroviral therapy (ART) drugs, like efavirenz, to lower vitamin D levels and decreased bone health.

Health Effects of Vitamin D Deficiency in People With HIV

Long-term inflammation and HIV disease progression have been linked to vitamin D deficiency in people with HIV. A few studies have indicated an association exists between vitamin D levels and higher CD4-positive cell counts, but this exact connection is not fully understood. CD4 cells are white blood cells that help fight infection.

Additionally, low levels of vitamin D have been linked to weight loss and loss of muscle mass in people with HIV. Vitamin D deficiency has also been associated with several conditions in people living with HIV including:

• Osteoporosis and osteopenia — Thinning and weakening of the bones, which increases the risk of bone fractures (breaks)
• Osteonecrosis — Weakening and potential collapse of part of the bone that doesn’t get enough blood
• Heart disease
• Diabetes
• Worse outcomes with tuberculosis infections

Although these conditions are associated with low vitamin D levels in people with HIV, more research is needed to determine whether the low levels directly contribute to these health outcomes.

Can Vitamin D Supplements Help Treat HIV?

Studies investigating the effects of vitamin D supplementation have had mixed results, and there’s not much information from research trials about the best amount of vitamin D for adults with HIV. This highlights the need for further research to determine whether taking vitamin D supplements can prevent or treat the conditions associated with low vitamin D levels in people with HIV.

Given that many people with HIV are deficient in vitamin D, your doctor may monitor your vitamin D levels using blood tests. Additionally, they might measure your bone density using a type of imaging test called a DEXA scan to make sure you are not developing osteoporosis. Based on the test results, your doctor might suggest either taking vitamin D and calcium supplements as part of your treatment plan or increasing your vitamin D levels by incorporating more vitamin D-rich foods and beverages into your diet.

You should never start any new supplements without discussing it with your doctor first. Currently, there is no established safe dose for vitamin D supplements for people living with HIV. Taking too much vitamin D could potentially cause more harm than good.

If your doctor does recommend vitamin D supplements, bear in mind that the U.S. Food and Drug Administration (FDA) does not regulate supplements as rigorously as it does medications. Supplement packaging may make claims that aren’t backed by science and may not accurately reflect a product’s ingredients. To purchase supplements from reputable sources, look for verification from respected third-party testing agencies, such as ConsumerLab.com, NSF International, UL, or U.S. Pharmacopeia.

Your Doctors Are Your Best Resource

While having a healthy level of vitamin D is beneficial for your overall health, vitamin D supplementation is not a cure for HIV. Antiretroviral therapy is the standard treatment for HIV treatment, effectively managing the virus and enabling people with HIV to lead fulfilling lives.

If you think you may be deficient in vitamin D, talk with your doctor or other health care providers. They can measure your vitamin D levels and follow up with medical advice if the levels are outside the normal range.

Talk With Others Who Understand

On myHIVteam, the social network for people with HIV and their loved ones, more than 37,000 members come together to ask questions, give advice, and share their stories with others who understand life with HIV.

Has your doctor tested you for vitamin D deficiency in light of your HIV status? Share your experience in the comments below, or start a conversation by posting on your Activities page.