Colloquially known as the “sunshine vitamin,” our bodies make vitamin D when our skin is exposed to sunlight — a built-in production system that hints at just how essential vitamin D is for our health.
However, modern lifestyles that keep us indoors don’t lend themselves to getting enough sun for sufficient vitamin D production. As a result, experts estimate that nearly a quarter of Americans aren’t getting enough vitamin D.
Despite its significance, questions remain: How much is enough? Can supplements effectively address a deficiency? Is there a benefit to taking more than the recommended amount?
The answers to these questions remain a topic of research and debate among researchers and doctors.
Over a century ago, researchers uncovered the role of vitamin D in bone health; the initial breakthrough found that vitamin D could cure rickets — a debilitating bone disease in children.
This discovery led to the fortification of staple foods like milk and orange juice that we see in grocery stores today.
Vitamin D deficiency can have similar effects on adults by causing a condition called osteomalacia, where bones do not mineralize properly, making them more susceptible to breaks and fractures.
Vitamin D regulates calcium and phosphorus levels in the blood. These two essential minerals then go on to build strong bones and carry out myriad other bodily functions.
Even with adequate vitamin D, we only absorb between 30 and 40 percent of the calcium from food; without enough vitamin D, that number drops to only 10 or 15 percent.
Vitamin D is fat-soluble, meaning it’s absorbed with dietary fats and stored in fat tissue and the liver, ready for release when our body signals the need.
The National Institutes of Health (NIH) recommends people between the ages of 1 and 70 have 600 International Units (IU) through diet and sun exposure. Age and pregnancy status affect vitamin D requirements. For instance, infants should get 400 IU, and those over 70 should aim for 800 IU.
Some physicians and researchers argue that these guidelines, established over a decade ago, are outdated based on current research.
Your body can naturally produce vitamin D when your skin is exposed to sunlight. Since getting enough vitamin D during winter can be challenging, diet becomes especially important. Foods high in vitamin D include fatty fish, like salmon, eggs, mushrooms and cheese made with vitamin D-fortified milk.
“The skin only produces enough vitamin D for health [from the] end of April to the end of September,” says John Gallagher, a medical doctor and endocrinology researcher at Creighton University, “probably 10 minutes [in the sun] daily. Skin covered by sunscreen will not make vitamin D.”
However, very few foods naturally contain vitamin D, which makes it difficult to get enough through diet alone.
(Credit: Ekaterina Markelova/Shutterstock)
While many individuals with vitamin D deficiency might not display clear symptoms, there are subtle signs that can indicate a potential shortfall. These can include:
Difficulty in sleeping
Bone tenderness or achiness
Depression or feelings of sadness
Unusual hair loss
Weakness in muscles
Increased susceptibility to illnesses
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Various physical and lifestyle elements can hinder the body’s production and absorption of vitamin D.
Several factors can limit sun exposure, reducing the amount of sunlight your skin receives. These factors can be environmental, personal or related to health and age:
Additionally, certain conditions can interfere with the proper processing and absorption of vitamin D, leading to deficiencies. These include:
Conditions that obstruct the absorption of dietary fats
Undergoing gastric bypass surgery
Having a higher body fat percentage
Vitamin D deficiency is associated with an increased susceptibility to infections and may lead to weakened immune function. Experts have sought to decode the link between vitamin D and immune health in recent years.
Now, a growing body of research hints at a potential relationship between long-term vitamin D deficiencies and the onset of autoimmune conditions like diabetes and rheumatoid arthritis. Yet, more research is needed to confirm these links.
Taking vitamin D supplements, when directed by a healthcare professional, may be a good option for addressing deficiency or insufficiency to avoid serious health problems. There are two main types of vitamin D supplements: vitamin D2 and vitamin D3.
Vitamin D2 (Ergocalciferol) is derived from plant sources and is often used in prescription supplements. It can also be found in fortified foods. While vitamin D2 can raise blood levels of vitamin D, it is generally considered less effective at maintaining adequate levels compared to vitamin D3.
Vitamin D3 (Cholecalciferol) is naturally synthesized in the skin when exposed to sunlight. It is also available as a supplement and is typically more effective at raising and maintaining blood levels of vitamin D. Vitamin D3 supplements are widely available over-the-counter and are often preferred.
Both vitamin D2 and vitamin D3 can be used to correct deficiencies when prescribed by a healthcare provider. However, vitamin D3 is generally preferred for supplementation due to its greater efficacy in maintaining adequate vitamin D levels.
Be sure to consult with your healthcare provider to find out which vitamin D supplement to use.
While rare, consuming excessive amounts of vitamin D can pose health risks. Excessive vitamin D intake from supplements can lead to calcium buildup in the blood.
This condition can trigger a range of unpleasant symptoms, including nausea, vomiting, weakness and frequent urination. Experts note that reaching hazardous levels is generally difficult despite these potential side effects. Your body naturally regulates vitamin D, eliminating excess amounts to maintain balance.
The importance of the sunshine vitamin is undeniable, impacting our bones and maybe even our immune systems. Ensuring you get enough, whether through sun exposure, diet or supplements, is essential while still being cautious of not overdoing it.