Sunshine in a Capsule: Vitamin D Supplements Explained and Who Should Take Them

Vitamin D has been linked to the maintenance of cardiovascular health, according to a systematic review meta-analysis published July 2024. More specifically, vitamin D “provides generally beneficial effects on blood pressure, blood lipid levels, and glycemic parameters.” This was especially the case among non-Westerners, participants with lower vitamin D levels, participants with a BMI under 30 and adults aged 50 and over.

Vitamin D is an important nutrient that supports healthy immune function and strengthens our bones, brains and more. Keep reading to learn more about the benefits, possible risks and who should take vitamin D supplements. Keep in mind that before taking any supplement, it is important that you consult your doctor to ensure it meets your health needs.

What is vitamin D?

Your body needs vitamin D for several crucial processes, from building healthy bones to regulating certain cellular functions. It also affects your brain, skin and muscle function.

When it comes to bone health, vitamin D plays an important role it maintains calcium and phosphorus balance by promoting absorption. Vitamin D is usually added to milk to increase calcium absorption, which takes place in the small intestine.

Vitamin D exists in two primary forms: D2 (ergocalciferol) and D3 (cholecalciferol). They function quite similar in your body, although D3 is more bioavailable and therefore more effective at increasing and maintaining adequate vitamin D levels in the bloodstream.

Good news: Your body has the ability to produce vitamin D itself when a chemical in your skin receives direct sunlight. Bad news: Most people can’t produce as much vitamin D as their body needs. This is especially true with limited sun exposure during the winter months, when the days get shorter and you spend less time outdoors. Others at higher risk of developing vitamin D deficiency include people with darker skin tones, fat malabsorption disorders, inflammatory bowel disease, or older adults.

Without enough of this vitamin, you are more susceptible to stress fractures. Some people also experience fatigue, aches and pains due to vitamin D deficiency.

If you think you may have this deficiency, ask your doctor for a blood test. They can help you determine if you are deficient in this vitamin and, if so, the best way to increase your levels. Some people benefit from adding more vitamin D-rich foods and drinks to their diet, while others need vitamin D supplements.

Foods with vitamin D

If you want to get more of this nutrient into your body in a safe, risk-free way, purchase foods with vitamin D. Some naturally occurring sources include:

• Tuna
  
• Trout
  
• Salmon
  
• Sardines
  
• Herring
  
• Mackerel
  
• Egg yolk
  
• Mushrooms
  
• Shrimp
  
• Cheese
  
• Beef liver
  

You can also find foods and drinks fortified with vitamin D. Remember, your body needs vitamin D to adequately absorb calcium. As a result, you often find it in milk and yogurt. Check the packaging. It should specifically say something like ‘fortified with vitamin D’.

You may also find vitamin D-fortified breakfast cereals, oatmeal and orange juice. In other words, food manufacturers have apparently decided that a healthy dose of vitamin D is a great way to start the day. Furthermore, these foods are fortified because they are affordable and accessible to most people.

If you have had a blood test and found that you are deficient in this vitamin, you can try switching to a D-rich diet. If another test shows that your vitamin D supplement is still low, it’s probably time to start exploring the benefits of vitamin D supplements.

Vitamin D Benefits

Whether you combine food and sunlight or add vitamin D supplements to your diet, getting enough of this nutrient makes a big difference to your body. In concrete terms, sufficient vitamin D can ensure:

Stronger bones

Studies show that vitamin D plays a crucial role in your body’s calcium absorption. And as you probably already know, calcium means strong, healthy bones. That’s why doctors often prescribe vitamin D supplements to children with diabetes rickets and people with hereditary bone disorders.

Because everyone has bones, it’s worth double-checking that you’re getting enough vitamin D. Getting enough vitamin D can help prevent and manage osteoporosis.

Reduced risk of heart disease and diabetes

Across the country, heart disease is the most common main cause of death. While many factors are at play here, studies have linked low levels of vitamin D to:

• Heart disease
  
• Myocardial infarction
  
• Hypertension
  
• Type 2 diabetes
  

If you’re looking for a way to defend yourself against some of the country’s most common health problems, it may be time to consider these benefits of vitamin D supplements.

A stronger immune system

Although low vitamin D levels can make you sick, the opposite can also be true. This vitamin works to activate your T cells, which helps your body fight infections. That means the benefits of vitamin D supplements may include a reduced chance of getting sick, along with the risk of getting sick reduce your risk for dysregulated immune system conditions such as rheumatoid arthritis, asthma and diabetes. However, more research is needed to fully understand the extent of vitamin D’s impact on these conditions.

A more balanced mood

Studies link insufficient vitamin D and depression. Additionally, even if you don’t suffer from a depressive disorder, low vitamin D levels can contribute to depressive symptoms such as low mood and apathy.

Reduced cognitive decline

Speaking of your brain: vitamin D can help with that. Studies appear to show a link between vitamin D deficiency and impaired cognitive function. Beyond that, early research suggests that low vitamin D levels may contribute to cognitive decline as we age.

In short, those vitamin D supplements can help you stay sharp, now and for years to come.

Disadvantages of vitamin D supplements

All this said, you can definitely have too much of a good thing when it comes to vitamin D supplements.

While experts recommend approximately 600 international units (IU) vitamin D per day is an intake of 4,000 IU per day or more for most adults considered unsafeespecially for those taking supplements without a known vitamin D deficiency. These high doses, especially over a longer period of time, are related to:

Hypercalcemia

Taking too much vitamin D can lead to: hypercalcemiaThis means that you have too much calcium in your blood. This can cause kidney stones and contribute to the hardening of your arteries, lungs and heart.

Nausea and vomiting

Too much vitamin D supplements can upset your stomach, leading to nausea and vomiting. If you have recently started taking these supplements and are feeling nauseous, it could be a sign that you are overdoing it.

Dehydration

Taking extremely high levels of vitamin D can cause toxicity. One of the main symptoms of vitamin D toxicity is intense dehydration.

Confusion

While some of the biggest benefits of vitamin D supplements center around your brain, too much can cause the opposite effect. People who take too much often report it disorientation and confusion.

Should You Take Vitamin D Supplements?

Screening for vitamin D is actually not currently recommended because the evidence is “insufficient to assess the balance of benefits and harms of screening for vitamin D deficiency in asymptomatic adults,” according to the U.S. Preventive Services Task Force. Instead, doctors test more for diagnostic purposes, such as if someone has a suspicious symptom. If you are concerned, consult your doctor.

If you are deficient in vitamin D, adjusting your diet may be enough to tip the balance. If you’re still low on this important nutrient after eating more D-rich foods, or you live in a climate where you don’t get enough sunlight, supplements can help. Your body needs vitamin D to keep your bones strong, boost your immune response and support the health of your heart and brain. Make sure you monitor your intake levels. About 600 to 800 IU per day should be sufficient, unless your doctor tells you otherwise.

Can you take too much vitamin D?

According to the National Institutes of Health, too much vitamin D can be harmful. This is known as vitamin D toxicity or hypervitaminosis D. More than 375 nmol/l or 150 ng/ml vitamin D in your blood is considered very high and can cause:

• Nausea
• Vomiting
• Muscle weakness
• Confusion
• Pain
• Loss of appetite
• Dehydration
  
• Excessive urination
  
• Thirst
  
• Kidney stones
  

Extremely high levels of vitamin D can lead to irregular heartbeat, kidney failure and death. This is usually caused by taking too many vitamin D supplements.

For example, for adults 19 years and older, 100 mcg (4,000 IU) is the daily upper limit for vitamin D from all sources, including supplements, foods, and beverages. However, a doctor may recommend a different upper limit if you have a vitamin D deficiency.