6 Risk Factors for Vitamin D Deficiency
An estimated 1 billion people worldwide, across all ethnicities and age groups, have a vitamin D deficiency according to a review published in the Journal of Pharmacology & Pharmoacotherapeutics . Vitamin D deficiency is being recognized as a world problem that can have serious health consequences for children and adults. Vitamin D is a fat-soluble vitamin that is produced from ultraviolet rays from the sun that strike the skin to trigger vitamin D production. Vitamin D promotes calcium absorption in the gut and maintains calcium and phosphate levels to give us strong bones. It also supports muscle function, cell growth, neuromuscular function and immunity.
In the body, vitamin D is linked with:
- Immune function
- Blood pressure regulation
- Muscle strength and mass
- Absorption of calcium
- Healthy weight management
- Overall bone and teeth health
Vitamin D deficiency can go undetected as the signs and symptoms are asymptomatic, but lead to several health problems like:
- Risk of stress fractures
- Muscle aches and weakness
- Muscle twitching
Several factors influence vitamin D levels. Here are the six important ones!
- Location. The further away from the equator you live, the less vitamin D producing UVB light that reaches the earth’s surface during winter. For example, residents in Minnesota may receive little if any of the vitamin from October through February. Short days and wearing clothing that covers arms and legs also limits UVB exposure.
- Skin color. Dark-skinned people tend to require more UVB exposure than light-skinned people to produce the same amount of vitamin D. This is due to melanin in the skin that makes it dark. It competes for UVB that stimulates the body’s vitamin D production. Sun screen will also limit skin’s ability by 97%.
- Body Composition. People who carry excess weight do not have a change in vitamin D production, but higher body fat concentrations affect levels of vitamin D in the blood. Remember that vitamin D is fat soluble, which means the more body fat the more diluted it gets. If you are overweight or obese with a BMI >30 you may need more vitamin D.
- Gastrointestinal disorders. Vitamin D is a fat-soluble vitamin, so fat is necessary for absorption. Those with Crohn’s, Celiac, or Inflammatory Bowel Disease are unable to absorb fat properly leading to a deficiency in fat soluble vitamins, like vitamin D.
- Aging. Skin production of vitamin D in older adults decreases due to skin changes with a reduced amount of the vitamin D precursor. Lifestyle factors with limited outdoor exposure and more layers of clothing also negatively impact vitamin D production. Lastly, renal production of vitamin D decreases due to diminishing renal function with age. These changing factors in vitamin D metabolism generate a higher risk for vitamin D deficiency.
- Dietary intake. Few foods contain vitamin D naturally, and if you avoid milk or follow a strict vegan diet you are at an increased risk. Since most of the natural sources are animal based, including fish and fish oils, egg yolks, fortified milk, and beef liver.
Limited intake requires fortified sources. Fortified means vitamin D has been added. Foods that contain vitamin D include; Fatty fish like mackerel, salmon, halibut, tuna, sardines and herring. Fortified sources include; milk, orange juice, yogurt and cereal. Mushrooms and egg yolks also contain traces of vitamin D. The recommended dietary allowances for vitamin D for male and females under the age of 70 is 600 units, and 800 for people over 70. For those under 12 months calls for an intake of 400 units a day.
Vitamin D content in food sources include:
- 6 oz. fortified yogurt = 80 IU
- 3 oz. of salmon = 794 IU
- 1 cup of fortified cereal = 40 IU
- 1 cup of fortified milk = 120 IU
- 1 egg yolk = 41 IU
- 1 cup of fortified orange juice = 137 IU
Vitamin D is important to overall health. The best way to have a healthy level of vitamin D is consuming foods rich in vitamin D and getting adequate sun exposure when possible. It’s important to note that resources and blood tests available to determine if you are vitamin D deficient. For more information, you should consult with your physician, dietitian or health practitioner before taking a vitamin D supplement or if you feel you are at risk for vitamin D deficiency.
Interested in learning more about your vitamin D status? Check out the website of the Vitamin D Society for more information. A more comprehensive table of Vitamin D concentrations and health are found here via the National Institute of Health.
As a registered dietitian nutritionist, I am very passionate about vitamin D an overall health. In addition to this article will be another illustrating the important role vitamin D plays in athletic performance.
In good health,
Wendi Irlbeck, MS, RDN