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Vitamin D Deficiency, Chances are You Have It

An estimated 1 billion people in the world are vitamin D deficient (American Journal of Clinical Nutrition). Are you one of them?

What is vitamin D?

Vitamin D is responsible for calcium absorption in the small intestine, which explains why it is linked to bone health and also why it is often coupled with calcium in fortified foods. This vitamin is also accountable for the maintenance of calcium and phosphate levels in the blood. Calcium and phosphate are two nutrients that greatly contribute to the healthy function of many body systems. Therefore, identifying vitamin D deficiency is critical, as the deficiency has been associated with an increased risk of osteoporosis, common cancers, autoimmune diseases, hypertension, and infectious diseases.

What foods contain vitamin D?

Vitamin D can be found naturally in foods such as tuna, mackerel, salmon, cod liver oil, sardines, egg yolks, and UV-exposed mushrooms. It can also be found in fortified foods such as milk, cheese, and some cereals.

Aside from food, vitamin D can be synthesized in the skin through UV radiation exposure, otherwise known as sunlight. However, there are many factors that influence the amount of vitamin D that the skin can make such as age, location, skin tone, and sunscreen use.

Why are so many people deficient?

Knowing that something as simple as taking a stroll in the sun can create vitamin D, it is baffling to know that so many people are still deficient.

Vitamin D deficiency has grown increasingly prevalent in the modern world due to an increase of jobs that require staying indoors for a majority of the day. Additionally, the scientific community has definitively determined a link between UV radiation and skin cancer. In response, we are advised to apply sunscreen or wear clothing that reduces sun exposure.

Older individuals also produce vitamin D less efficiently, as their skin is thinner and consequently there are fewer cells that can synthesize the vitamin. Living in a sunny location can help increase one’s exposure to sunlight, but on the other hand, living in a less sunny location can lead to the opposite. Lastly, skin tones can affect your ability to absorb sunlight, with lighter skin tones making it easier and darker skin tones making it more difficult.

Here’s what we recommend:

At your next doctor’s visit, ask your doctor to include a vitamin D blood test in your annual check up. From there, your doctor will inform you of your vitamin D status.

If your blood test indicates a deficiency, the doctor will recommend an appropriate dosage for a vitamin D supplement. The vitamin D supplement will contain vitamin D3, the form of vitamin D that is most easily absorbed.

It is important to note that vitamin D overdose is possible from supplementation, but not from sun exposure or diet. The guidelines from the Institute of Medicine for vitamin D supplementation is:

●Age 0 to 1 year: 400 to 1,000 International Units (IU) daily

●Age 1 to 18 years: 600 to 1,000 IU daily

●All adults over age 18: 1,500 to 2,000 IU daily

●Pregnant or nursing women under age 18: 600 to 1,000 IU daily

●Pregnant or nursing women over age 18: 1,500 to 2,000 IU daily

If you have any questions, please talk to your doctor or dietitian.

Interested in learning about weight goal and nutrition needs? Schedule a free body weight and fat% analysis with Hazel at 626-283-5128 or email to

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