How to Increase Vitamin D Levels All Year

The nickname “sunshine vitamin” makes vitamin D sound easy to manage. Sunshine, though, doesn’t come with a dosage label. The amount your skin produces varies with the season and generally declines with age. Spending longer in the sun also means more exposure to ultraviolet light.

Vitamin D helps your body absorb calcium and supports normal muscle function. Food can supply it, and supplements may help when intake falls short. The harder question is knowing if you’re getting enough in the first place. Understanding who is at greater risk and how vitamin D levels are measured can help you make an informed choice.

Vitamin D – It’s Not Like Other Vitamins

Vitamin D is an outlier in the vitamin world because its active form functions much like a hormone. Other vitamins typically act as supports for biochemical reactions, helping the body’s machinery operate. For example, vitamin C assists enzymes involved in making collagen and also acts as an antioxidant.

Acting more like a hormone, vitamin D serves as a chemical messenger that changes what cells do. Whether manufactured in skin exposed to ultraviolet light or ingested through food or supplements, it ultimately enters our cells, where it causes them to make more or less of certain proteins.

Why the Body Needs Vitamin D

Vitamin D affects important biochemical processes:

• Calcium absorption and bone health - Vitamin D helps the intestines absorb calcium from food. Without enough vitamin D, you can consume adequate calcium but still not absorb enough of it.
• Nerve and Muscle function - Vitamin D is involved in normal muscle contraction and strength. Adequate vitamin D also supports proper electrical and chemical signaling by nerves.
• Immune function - Immune cells have vitamin D receptors and use vitamin D in several aspects of their activity.
• Cell growth and regulation - Vitamin D receptors occur in many tissues throughout the body, and vitamin D influences how certain genes are switched on and off.

Symptoms of Vitamin D Deficiency

You might not even know you have a vitamin D deficiency because mild or moderate deficiency often causes no obvious symptoms. However, when symptoms do occur, particularly with a more substantial deficiency, they can include:

• Muscle weakness - This is most common in the thighs, hips, and shoulders, which might be noticeable if someone has increased difficulty climbing stairs or getting up from a chair.
• Bone pain or tenderness – This may be experienced as a dull ache in the lower back, hips, pelvis, ribs, or legs.
• Muscle aches, tingling, cramps, or spasms – These may arise from low blood calcium.
• Fatigue or a general lack of energy - Fatigue has many possible causes, but vitamin D deficiency could be one factor.
• Fragile or weakened bones – Vitamin D deficiency can contribute to osteoporosis and increase fracture risk. Prolonged, severe deficiency can cause osteomalacia, in which adult bones don't mineralize properly.

Vitamin D deficiency is particularly risky for older adults, as weakened muscles can increase the likelihood of falls, and weakened bones can lead to more fall-related fractures. Also, the National Institutes of Health has identified other groups at greater risk of inadequate vitamin D, including people who have:

• Limited sun exposure
• Darker skin
• Conditions that impair fat absorption
• Obesity conditions
• History of gastric bypass surgery

Testing for Vitamin D Deficiency

Because the symptoms mentioned above could be attributed to other causes, vitamin D deficiency generally can't be diagnosed by symptoms alone. Healthcare professionals use a blood test called 25-hydroxyvitamin D [25(OH)D], which measures the body's vitamin D status. For healthy individuals, a 20–50 nanograms/milliliter level is deemed sufficient. But if the level is less than 20 nanograms/milliliter, it indicates a deficiency of some type.

How to Increase Vitamin D Levels

So, if you’re diagnosed with a deficiency, what can you do? The following are simple ways to increase your vitamin D levels:

Eat Vitamin D-rich Foods

Although your body produces vitamin D in response to sunlight, you also acquire it through your diet. There are two categories of food when it comes to vitamin D. First are naturally occurring sources such as fatty fish (e.g. - salmon, trout, tuna, and sardines), egg yolks, cheese, and liver. The only vegan option is mushrooms exposed to UV light. The other category is fortified sources to which vitamin D is added. These foods include dairy milk, some plant-based milks, breakfast cereals, and some orange juices.

Fish liver oils and fatty fish flesh are two of the greatest vitamin D sources, while egg yolks, beef liver, and cheese have smaller amounts.

Take Vitamin D Supplements

Supplements may be the simplest and most effective way to boost vitamin D levels. Because of the risk of skin cancer associated with using sunlight to increase vitamin D levels and the potential difficulty of obtaining adequate vitamin D through diet, supplements are frequently the first line of defense for vitamin D-deficient individuals. Several multivitamin supplements contain vitamin D, and vitamin D is also available as a standalone supplement.

Vitamin D exists in two primary biological forms, D2 and D3. D2 is often derived from plants, while D3 is derived from animals. In a 2017 study, D3 is substantially more beneficial than D2 at maintaining and increasing overall vitamin D levels, so strongly consider supplements containing this type.

It's best to consult your doctor before taking any supplements to determine if they're necessary and to ensure that you're taking the correct dosage. 

Get Vitamin D from the Sun

Exposing yourself to the sun more frequently will increase your vitamin D levels. When ultraviolet rays from the sun strike your skin, they trigger a chemical process that leads to vitamin D production. Although the amount of sun required to produce sufficient vitamin D varies, the NIH notes that spending 5 to 30 minutes in the sun between 10 a.m. and 4 p.m. every day or twice weekly is probably sufficient.

That said, UV exposure is a known carcinogen, be it from the sun, a UV lamp, or a tanning bed. Consult your healthcare professional to see whether getting more UV light is right for your situation.

Sunlight has no measuring spoon. Two people can spend the same afternoon outdoors and produce different amounts of vitamin D. Neither can tell how much they made by checking the clock. Take the walk because you enjoy it, and protect your skin while you’re out. If you’re concerned about vitamin D, ask your healthcare provider to review your risk factors and what you get from food or supplements. That conversation gives you a sounder basis for deciding if anything needs to change.