Although there has been much debate over the benefit of vitamin D supplements, the jury is still out. More people than ever are taking vitamin D supplements but there is some controversy surrounding the recommendations. This leaves many people confused.               

Here are answers to some of the most common questions, and what we know for sure.

What is vitamin D?

Vitamin D is an essential nutrient needed for strong, healthy bones. We get it through things we eat and through sunshine.

Research shows that vitamin D is crucial for our skeletal health because it helps the body absorb calcium from our diets. Not enough and we can develop osteoporosis and potential bone fractures.

New evidence indicates that vitamin D may also affect our immune and cardiovascular systems. In fact, some studies have associated low vitamin D levels with neuromuscular disease, cancer, and obesity. However, there is no concrete evidence that links these diseases with a vitamin D deficiency.

How are Vitamin D levels determined?

A simple blood test can determine your vitamin D level.  Unfortunately, there is no clear recommendation on who should be tested and it is not typically included in the routine blood work ordered for an annual physical. The exceptions are for patients who are at higher risk for developing a vitamin D deficiency. These include patients who have or are at risk for developing osteoporosis, malabsorption syndromes, celiac disease, or have had gastric bypass surgery.

When a patient reports symptoms of fatigue, malaise, or depression, a doctor may order a test. Many people do take vitamin D supplements, believing that it will help with fatigue or depression, although there is no concrete evidence to support this theory. If you feel you may be at risk for being vitamin D deficient, discuss it with your health care provider.

What are the signs of low vitamin D?

Some individuals have few or no symptoms, while others may experience bone pain, muscle weakness or difficulty walking, which may increase the risk for falls.

Depending on the duration and severity of the deficiency, low levels of vitamin D can cause osteoporosis and increase your risk for fractures. An extreme and prolonged deficiency will cause rickets. There are also possible links between a vitamin D deficiency and many autoimmune diseases, cardiovascular disease, multiple sclerosis, and diabetes. However, evidence is inconsistent and only demonstrates an association between low levels of vitamin D and increased occurrences of these diseases. 

What foods have vitamin D?

Vitamin D dietary sources are somewhat limited, but it can be found in fish like salmon, tuna, mackerel, and fish liver oils. It is also found in small amounts in cheese, egg yolks, shiitake mushrooms, and beef liver. Vitamin D is also fortified in many foods such as milk, dairy products, orange juice, tofu, breads, and cereals.

When should I take a supplement? 

Vitamin D is sometimes called the “sunshine vitamin” because it is made in the skin after exposure to ultraviolet light. During the winter months in many parts of the country, the sun’s rays are not strong enough for the body to produce vitamin D. Our society has also changed significantly in the past decade. Few spend as much time outdoors as they used to, meaning their skin sees less exposure to sunlight. Also, while more people are using sunscreen to protect themselves, that means less exposure to the sun’s ultraviolet B rays.

Older individuals, people who have darker skin, and those who are overweight also have a more difficult time producing vitamin D. Some studies estimate that as much as 40 percent of the population may be deficient in vitamin D. 

As a rule, supplements are best for those who do not get regular sun exposure. Healthy adults should aim for at least 600-800 IU of vitamin D daily. Those over 70 should have at least 800 IU units. Individuals who have a confirmed vitamin D level of below 12ng/ml should take higher levels of vitamin D as directed by their health care provider. For reference, most multivitamins contain about 400 units of vitamin D.


Taking extremely high doses of a supplement can be a health hazard. Usually, toxicity does not occur unless you consume 40,000 IU daily for a period of several months. Those with elevated calcium levels should also avoid taking vitamin D. For most individuals, a daily 600 IU vitamin D supplement is most likely a safe and good idea. Of course, a supplement should be taken as part of a healthy diet and a regular exercise routine, preferably outdoors.

As with any supplement, it is wise to set up an appointment with a primary care provider beforehand to ask questions and be sure the supplement is right for you.

Coastal Medical Primary Care Team

Coastal Medical Primary Care Team provides crucial services for your long-term health and well-being at several locations in Rhode Island.