Key takeaways:
Your body relies on vitamin D to keep your bones, heart, and immune system healthy.
Most vitamin D comes from the sun. But it’s also found in some foods, and can be taken as a supplement.
Vitamin D deficiency can increase the risk of developing some health conditions or worsen them.
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You need vitamin D for strong, healthy bones, but that’s not all it’s good for. Research shows that having too little vitamin D, also known as vitamin D deficiency, is related to a host of conditions — from heart disease to dementia.
What is vitamin D deficiency?
Vitamin D deficiency is when the level of vitamin D in the body falls below what the body needs to stay healthy. Your vitamin D level can be determined with a blood test.
If you’re not getting or absorbing enough vitamin D, it can affect your health. That’s because vitamin D is important for strong bones, muscles, and immune system.
How does vitamin D deficiency affect the body?
Vitamin D deficiency leads to hypocalcemia (low calcium levels). That’s because vitamin D plays a role in regulating calcium levels. Hypocalcemia then triggers hyperparathyroidism (overactive parathyroid glands), as your parathyroid glands attempt to normalize the calcium level. These glands do this by activating the cells that break down bone to release calcium. Over time, this weakens and thins the bones.
In addition to weaker bones, vitamin D deficiency can lead to other health problems. (More on this below.) In most adults, low vitamin D doesn’t cause any symptoms. But, if it’s severe or chronic, it can cause vague symptoms, like fatigue and pain. In young children, vitamin D deficiency can lead to rickets, a painful condition that causes bone deformities and dental problems.
How much vitamin D do you need?
The amount of vitamin D that you need every day depends on your age and, in some cases, other factors. The chart below details how much daily vitamin D you should be getting based on your age, according to the U.S. Food and Nutrition Board.
Age range | Recommended daily intake of vitamin D | Maximum recommended daily intake of vitamin D |
|---|---|---|
0-12 months | 400 IU | 1000-1500 IU |
1-13 years | 600 IU | 2500-3000 IU |
14-18 years | 600 IU | 4000 IU |
19-70 years | 600 IU | 4000 IU |
71+ years | 800 IU | 4000 IU |
Pregnant and breastfeeding people of any age | 600 IU | Refer to your prenatal care team. |
If you live in cooler, grayer areas or if you have a darker skin tone, you might need to take in more vitamin D than someone who lives in a sunnier environment or has lighter skin. That’s because exposure to sunlight is the main way you absorb vitamin D.
Which conditions and diseases are linked to vitamin D deficiency?
Below, we discuss seven conditions and diseases that have been linked to vitamin D deficiency.
1. Diabetes
If you have a vitamin D deficiency, you’re more likely to develop Type 2 diabetes. A vitamin D deficiency can also make it harder for you to control your blood sugar if you already have diabetes. That’s because vitamin D helps your body make more insulin. And it helps your body use insulin better.
Vitamin D also helps control inflammation in the body. Too much inflammation can lead to higher blood sugar. That may be particularly important for people with diabetes who have foot ulcers. Without enough vitamin D, foot ulcers and other skin wounds heal more slowly.
2. Heart disease
You probably know about common risk factors for heart disease, like high blood pressure and high cholesterol. But low levels of vitamin D can also increase your risk of heart disease.
Vitamin D helps your blood vessels relax and widen. Without enough vitamin D, your blood vessels aren’t as stretchy, and inflammation and clotting are more likely to occur. Vitamin D also helps lower your risk of heart disease by lowering your risk of diabetes.
3. Colorectal and bladder cancer
Higher vitamin D levels have been linked to lower risk of colorectal and bladder cancer. Unfortunately, experts don’t yet know exactly how or why vitamin D deficiency might be linked to cancer. It’s also unclear why supplementing vitamin D doesn’t help prevent cancer. Research is ongoing.
4. Dementia
The exact relationship between vitamin D and brain function isn’t known. But it’s true that patients with dementia — including Alzheimer’s disease — are more likely to be vitamin D deficient than not. More research is needed to determine if supplementation can help prevent dementia.
5. Depression
By stimulating the brain to release “happy hormones,” like serotonin and dopamine, vitamin D plays an important role in mental health and mood. These hormones are the ones that help you feel a sense of well-being and happiness. This may explain why people who are vitamin D deficient are more likely to have symptoms of depression. Studies suggest vitamin D supplementation may improve these symptoms.
6. Erectile dysfunction
As mentioned earlier, vitamin D can help relax and widen the blood vessels. Having stretchy blood vessels is critical to getting an erection, which requires blood to be able to flow freely into the vessels in the penis. If those vessels are too stiff, you may not be able to get or keep an erection, a condition known as erectile dysfunction.
7. Osteoporosis and bone disorders
Perhaps one of the most well-known consequences of vitamin D deficiency is osteoporosis. This condition causes bones to be weak and brittle due to a lack of calcium. Likewise, a condition known as rickets, which is characterized by weakened bones and stunted growth, affects children who have prolonged low vitamin D levels.
What are common symptoms of vitamin D deficiency?
How do you know if your vitamin D levels are low? Depending on how low your levels are, you might notice one or more of these symptoms:
Bone or muscle pain
Slow healing of wounds
Depressed or irritable mood
Fatigue and tiredness
Hair loss
Delays in growth or development (for children)
Hard-to-control blood sugar
Muscle twitches
Being prone to breaking bones
Issues with memory or concentration
However, many of these signs could be related to another condition. And many people with low vitamin D levels don’t notice symptoms at all. So, it’s a good idea to get your vitamin D level checked.
How is vitamin D deficiency diagnosed?
A simple blood test can determine your vitamin D level. Specifically, it measures 25-hydroxyvitamin D. You can ask your primary care provider or other healthcare professional about getting your vitamin D level checked.
How is vitamin D deficiency treated?
Vitamin D mainly comes from sunlight, select foods, and supplements.
Sunlight
You can get more vitamin D through direct exposure to the sun. That’s because when your skin is exposed to UV rays, it triggers vitamin D synthesis. Some experts recommend up to 30 minutes of UV exposure per day to maintain a healthy vitamin D level. But some studies suggest that as little as 9 minutes per day can help.
Foods
Most foods aren’t high in vitamin D, unless they’re fortified with it. Most of the U.S. milk supply is fortified with vitamin D, as are breakfast cereals and orange juice. And you may get some vitamin D from fatty fish (like salmon and tuna), mushrooms, and egg yolks.
Supplements
If you don’t get enough vitamin D from sun and food, supplements are a good option. How much you need depends on your age and which types of supplements you take. Vitamin D supplements come in two forms: vitamin D2 and vitamin D3.
You can find safe supplements that are verified by the U.S. Pharmacopeia (USP). It’s always a good idea to tell your doctors and pharmacist about any supplements you’re taking, including vitamins.
Frequently asked questions
Both supplements increase vitamin D levels in the blood. But vitamin D3 tends to have a greater effect, and the effect lasts longer. Both forms are absorbed well in the gut.
Vitamin D is a fat-soluble vitamin that’s absorbed by the gut. So, people with digestive conditions that prevent fat absorption may not get enough vitamin D through diet or supplements.
The evidence regarding sunscreen’s effects on vitamin D levels is a bit mixed. Some studies don’t show a link between sunscreen use and low vitamin D levels, whereas some do.
Both supplements increase vitamin D levels in the blood. But vitamin D3 tends to have a greater effect, and the effect lasts longer. Both forms are absorbed well in the gut.
Vitamin D is a fat-soluble vitamin that’s absorbed by the gut. So, people with digestive conditions that prevent fat absorption may not get enough vitamin D through diet or supplements.
The evidence regarding sunscreen’s effects on vitamin D levels is a bit mixed. Some studies don’t show a link between sunscreen use and low vitamin D levels, whereas some do.
The bottom line
Not having enough vitamin D is a common problem. But most people don’t have symptoms or know that their levels are low.
Over time, vitamin D deficiency can increase the risk of some health conditions. And, for people who already have those conditions, it can make treatment more difficult. Your healthcare team can help you check your vitamin D level and develop a plan to increase it, if needed. This can help lower your risk of disease and improve your physical and mental health in the long run.
Why trust our experts?
References
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Oncer, C., et al. (2020). Vitamin D and male erectile function: An updated review. The World Journal of Men’s Health.
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USP. (n.d.). USP verified products.
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