Looking a little thin up top? Hair loss can occur for a variety of reasons, the most common of which is hormonal hair loss caused by male pattern baldness. Other common causes of hair loss include stress and, in some cases, deficiencies of important vitamins and minerals.
If you’ve searched online for information about vitamins and hair loss before, you might have heard of a link between vitamin D and hair loss.
Although research is somewhat limited, there’s evidence that vitamin D deficiency can affect healthy hair growth, potentially resulting in shedding, thinning and patchy hair loss that affects certain parts of your scalp.
Below, we’ve discussed what vitamin D is and how it fits into the hair growth process. We’ve also explained how vitamin D deficiency may affect your hair, as well as what you can do to make sure you have optimal vitamin D levels throughout the year.
Vitamin D is an essential, fat-soluble vitamin that plays a role in numerous biological processes within your body.
Unlike most vitamins, vitamin D isn’t commonly found in foods. While some foods, such as milk, soy and certain types of fish, contain vitamin D, most vitamin D is produced endogenously when UV rays from sunlight come into contact with your skin.
In its natural form, vitamin D is biologically inert. To use vitamin D, your body needs to convert it into a usable form using the liver and kidneys. This complex, multi-step process is referred to as hydroxylation, and allows your body to use vitamin D for a variety of important processes.
Vitamin D plays a role in countless biological processes within your body. It’s responsible for:
Vitamin D also plays a key role in preventing certain diseases. People with low levels of vitamin D have an increased risk of developing rickets and osteomalacia — two diseases that can affect the health and integrity of your bones.
Low levels of vitamin D are also linked to certain forms of hair loss — a topic we’ve discussed in more detail below.
Research has shown that people who are deficient in vitamin D often experience some degree of hair loss. For example, one study of women aged between 18 and 45 found that low levels of vitamin D2 were associated with two common types of hair loss.
A separate study published in 2014 found that vitamin D deficiency is linked to alopecia areata — a form of patchy hair loss that’s caused by an autoimmune disorder.
Although the precise role of vitamin D in hair growth isn’t well understood, research shows that vitamin D receptors play an important role in the anagen phase of the hair cycle — the phase in which new hairs grow from the follicle to their full length.
In short, vitamin D deficiency definitely appears to be associated with hair loss. However, being deficient in vitamin D isn’t the only reason you may lose hair. Other common causes of hair loss include:
If you’re shedding more hair than normal and think that you could be deficient in vitamin D, the best thing to do is to talk to a healthcare professional.
Your healthcare provider will be able to diagnose vitamin D deficiency via a 25-hydroxy vitamin D blood test. This is a type of blood test that checks for 25-hydroxy vitamin D — a common form of vitamin D that circulates in your blood.
Vitamin D deficiency is surprisingly common. Up to one billion people worldwide, approximately 13 percent of the world’s entire population, are deficient in vitamin D.
If you’re severely deficient in vitamin D, you may notice certain symptoms other than hair loss. Common symptoms of vitamin D deficiency include:
Certain factors, such as your age, ethnicity and habits, may increase your risk of being deficient in vitamin D. You may have a higher risk of vitamin D deficiency if you:
Vitamin D deficiency is also common in breastfed infants. If you have an infant who is breastfed, your healthcare provider may recommend providing them with a vitamin D supplement to avoid developing a vitamin D deficiency.
If you’ve been diagnosed with a vitamin D deficiency, your healthcare provider will likely recommend the use of a vitamin D supplement. They may also recommend making some changes to your diet and habits to increase the amount of vitamin D you consume via food or produce naturally.
You can get more vitamin D by:
Although it’s important to take in a certain minimum amount of vitamin D for optimal health, it’s definitely possible to get too much vitamin D.
Your body limits the amount of vitamin D that it will produce due to sun exposure. This means that there’s no real risk of you “overdosing” on vitamin D if you spend too much time outside on a sunny day, although there are obviously other risks involved in excessive sun exposure.
However, overusing vitamin D supplements can cause something called vitamin D toxicity — a potentially harmful condition that can cause nausea, vomiting, constipation, weakness, weight loss, reduced appetite, heart rhythm problems and even damage to your kidneys.
To avoid vitamin D toxicity, only use vitamin D supplements as recommended by your healthcare provider or other healthcare professional.
If you’ve noticed your hair shedding or looking thin and think that it could be due to a vitamin D deficiency, talk to your healthcare provider. They will be able to test you for a vitamin D deficiency and, if appropriate, may recommend using a vitamin D supplement.
You may also be able to increase your vitamin D levels by changing your diet to include more foods that contain vitamin D, or by spending 10 to 15 minutes outside during sunny weather a few times each week.
There are numerous reasons that you might lose hair. While a vitamin D deficiency could be a cause of your hair loss, it may also be due to male pattern baldness, stress, use of medication or many other factors.
Dealing with hair loss can be a stressful experience. Luckily, several science-backed treatment options are available that can help you slow down or stop hair loss. Some might even help you to regrow hair in areas of your scalp where your hair has started to thin.
Our guide to minoxidil and finasteride goes into detail on the science behind two of the world’s most effective hair loss treatments to explain how they work and how you can use them to take control over your hair for good.