Natural sources of vitamin D and the role it plays in our health

Kiran Campbell, RDN - Registered Dietitian Nutritionist

Did you know there are other natural sources of vitamin D besides sunshine? Including natural sources of vitamin D in your diet can prevent deficiency, which can lead to other health issues.

Read on to learn about the importance of vitamin D in our body and how to get your daily dose.

Why do we need natural sources of vitamin D?

Natural sources of vitamin D and other nutrients are the most ideal means for our bodies to absorb and assimilate them properly. Vitamin D is a fat-soluble vitamin that also functions as a hormone or prohormone within our bodies. Like hormones, it controls different pathways that affect our health.

Because it is a fat-soluble vitamin, our bodies require some fat from our diet to help absorb it.

What does vitamin D do for your body?

Vitamin D is vital in many bodily functions, from helping absorb nutrients to enhancing mood. It is most famous for keeping bones and teeth healthy, strong, and dense through calcium absorption. Without adequate vitamin D, bones can become thin, misshapen, and easily broken. Vitamin D also provides these other functions, including:

Helping the body absorb calcium and phosphorus
Supporting immune function
Reducing inflammation
Maintaining muscle strength
Preventing high blood pressure and heart disease

Mental health and other roles

Maintaining adequate levels of vitamin D is also crucial to mental health, as low vitamin D levels have been associated with higher rates of depression.

Additionally, as the prevalence of diabetes and vitamin D deficiency rises, researchers are also exploring the link between low vitamin D levels and the development of type 1 and 2 diabetes. Some studies show that healthy vitamin D levels may support pancreatic function, which produces insulin, a critical hormone that carries sugar out of the blood and into the body's tissues.

Recommended daily intake of vitamin D

One national survey indicated that U.S. adults aged 20-29 were more likely to be vitamin D deficient, especially those with a lower income.

The FDA's Food and Nutrition Board established a Recommended Dietary Allowance (RDA) for vitamin D based on minimal sun exposure, as shown below.

How much vitamin D do I need?

Age	Males and Females	Pregnancy and Lactation
19-70 years	15 mcg (600 IU)	15 mcg (600 IU)
Over 70 years	20 mcg (800 IU)

The tolerable upper intake level (UL) for supplemental vitamin D is 100 mcg (4000 IU) for everyone ages nine and older. This is the maximum daily level advised without adverse health effects, and it should not be exceeded unless advised by a doctor.

Natural sources of vitamin D

We can get vitamin D naturally from two different sources: sunlight and food.

Sunlight and vitamin D synthesis

Maybe you’ve heard vitamin D called the “sunshine vitamin?" Most people meet at least half their vitamin D needs through sunlight exposure.

Vitamin D is synthesized when the skin absorbs UV rays from sunlight. Approximately 5-15 minutes of sun exposure without sunscreen on about 6% of the body (face, arms, legs, or back) two to three days per week should lead to adequate vitamin D synthesis.

Your body can only synthesize a limited amount of vitamin D from sunlight, so you must be cautious about excessive sun exposure to prevent skin cancer.

However, getting adequate amounts of vitamin D from sunlight can be difficult in some parts of the world, especially in the northern hemisphere during fall and winter. Individuals with limited sun exposure should consider taking a vitamin D supplement. Most multivitamin-mineral supplements contain at least 400 IU of vitamin D, a sufficient daily dose.

Can you get vitamin D through a window?

Unfortunately, the UVB rays responsible for vitamin D synthesis do not penetrate glass, so you cannot get vitamin D through a window.

Foods rich in vitamin D

It is challenging to get adequate vitamin D from food because very few foods naturally contain it. The richest sources of vitamin D include:

Fatty fish (trout, tuna, salmon, and herring)
Cod liver oil
Beef liver
Cheese
Egg yolks
Foods fortified with vitamin D (milk, yogurt, cereals, and orange juice)

Are you at risk for vitamin D deficiency?

Only high-risk individuals should get their levels tested routinely.

Those at highest risk of vitamin D deficiency include:

Children and adolescents 18 and younger
Individuals 75 and older
Pregnant women
People with prediabetes

In addition, those with dark complexions and overweight individuals are also more likely to be vitamin D deficient. Ask your doctor if your vitamin D level should be tested. Supplements can help you get it to a desirable level if it is low.

Including natural sources of vitamin D daily can reap the benefits of bone health, strengthen your immune system, and build your prevention arsenal against type 1 and type 2 diabetes, high blood pressure, and heart disease.

Natural sources of vitamin D and the role it plays in our health

Why do we need natural sources of vitamin D?