Nutrition Connection: Vitamin D: The Sunshine Vitamin

(reprinted from Dietary Manager, September 2009)

How many patients or residents in your facility have signs of vitamin deficiencies? Do you look for signs of vitamin deficiencies during your quarterly and annual reviews of residents? Vitamin D is the most common nutrient deficiency in older adults.

The first medical description of a Vitamin D deficiency was in 1645. English physicians observed that children who lived in the inner city had growth retardation, skeletal deformities, and bowed legs. They called the disease rickets—meaning ‘to twist or bend.’ Children who lived in rural areas did not have rickets. Two hundred years passed before the relationship between sunlight and rickets was discovered.

Vitamin D deficiency continues to be a hidden condition in adults and seniors. The effects to the skeleton of an adult with a vitamin D deficiency are more subtle. A vitamin D deficiency reduces the bone mineral density, making bones weaker. It may trigger osteoporosis or make osteoporosis worse. Vitamin D deficiency is also associated with muscle weakness and bone pain. Adults and seniors with a vitamin D deficiency have a higher risk of falls and an increased risk for chronic and autoimmune diseases. Improving vitamin D status has been shown to dramatically reduce the risk of falls in older adults. A growing number of research studies show that improving vitamin D status reduces the risk for other diseases and improves overall health and well-being.

Sources of Vitamin D: Sunlight

Vitamin D is a unique fat-soluble vitamin because 90 percent of the requirement is met by casual exposure to sunlight. Sunlight consists of UVA rays, UVB rays, and UVC rays. Only UVB rays are involved in producing vitamin D. Several factors limit the amount of UVB rays that penetrate the skin and result in the production of vitamin D. Factors include:

• age
• skin type
• where you live
• season of the year
• time of day
• use of sunscreen
• heavy cloud cover
• air pollution

Age

Studies comparing blood levels of vitamin D following seven consecutive days of sun exposure show that older adults produce much less vitamin D than younger adults. Also, older adults have minimal vitamin D production after several days of sun exposure. This research demonstrates that older adults are much more likely to be vitamin D deficient. Individuals living in healthcare facilities or who have limited exposure to sunlight are at greatest risk.

Skin Type

There are six sun-reactive skin types. The types of skin are not related to race, but sun sensitivity or the amount of melanin in the skin. Melanin absorbs UVB rays and limits the production of vitamin D. Individuals with higher levels of melanin have darker skin color and require longer exposure to sunlight to make the same amount of vitamin D compared with lighter skin types.

Location, Season of Year, and Time of Day

Where you live, the season of the year, and the time of day influence the amount of vitamin D produced from sun exposure. Vitamin D production from sun exposure is year round if you live in the southern region of the United States or countries near the equator. However, if you live north of Atlanta, Georgia, vitamin D production is best during the months of March-October. Very little vitamin D is produced from sun exposure during the winter months.

Time of day is also critical to vitamin D production. The greatest vitamin D production from sun exposure occurs between 11 am and 2 pm. In the early morning and late afternoon, very little vitamin D is produced even in the summer months.

Sunscreen

Sunscreen or sun block products are promoted to reduce the risk of skin cancer. Most of the products block primarily UVB rays—the rays that stimulate vitamin D production. However, it is the UVA rays that cause the deadly form of skin cancer melanoma.

Sunscreen products have a sun protection factor (SPF) or rating ranging from 2 to 60. The numbers refer to the product’s ability to screen or block out the UVB rays. The SPF is calculated by comparing the amount of time needed to produce a sunburn on protected skin to the amount of time needed to cause a sunburn on unprotected skin. Sunscreen products with higher SPF provide longer protection from sunburn than products with lower SPF.

Sunscreen not only prevents sunburn, it also blocks the production of vitamin D through the skin. A product with an SPF of 8 reduces the capacity of the skin to produce vitamin D by 95 percent, and those with an SPF rating of 15 reduce the capacity by 98 percent.

Individuals with a history of skin cancer or who are on medications that increase sun sensitivity need to check with their physician about increasing sun exposure and the use of sunscreen. Medical experts have different opinions about the benefits of sun exposure vs sunscreen.

Cloud Cover and Air Pollution

Rickets was first reported in children living in European cities with heavy air pollution. The presence of heavy cloud cover or air pollution reduces the UVB rays that reach the skin. Individuals living in heavily polluted areas or areas that have few sunny days are at greater risk of a vitamin D deficiency.

Sources of Vitamin D: Food and Supplements

Very few foods naturally contain vitamin D. Oily fish such as sardines, mackerel, and salmon are good sources of vitamin D. Some foods are fortified with vitamin D including milk, yogurt, orange juice, cereals, and some breads.

Vitamin supplements contain different amounts of vitamin D. Experts recommend that vitamin D supplements include calcium as well. Refer to the product label to determine the levels of vitamin D and calcium provided.

Current Recommendations for Vitamin D Intake

The Institute of Medicine has established an RDA, AI (Adequate Intake) and UL (Tolerable Upper Limit) for vitamin D. See table for values. These values are currently under review by an expert panel. The RDA and AI levels assume that dietary intake provides only 10 percent of the daily requirement for vitamin D and 90 percent will come from sun exposure.

Risk Assessment for Vitamin D Deficiency

Vitamin D deficiency is a major public health problem for adults over the age of 50 years. The primary cause is inadequate sun exposure or inadequate vitamin D intake. However, many older adults may have a vitamin D deficiency caused by other health problems such as malabsorption disorders, chronic renal failure, and severe liver disease. Anticonvulsant medications also interfere with vitamin D utilization.

The Institute of Medicine has identified two criteria for estimating vitamin D requirements:

• Blood level tests of 25(OH) vitamin D
• Skeletal health

Blood levels of 25(OH) vitamin D are ordered by the physician. Normal levels are 32 ng/L/80 nmol/L.

Skeletal health is based on bone mineral density and fracture risk. For individuals living in long-term care facilities, use the MDS to identify risk factors for poor skeletal health. Active Disease Diagnosis (Section I) associated with vitamin D deficiency include osteoporosis, hip fracture, other fracture, and malnutrition. Health Conditions (Section J) associated with vitamin D deficiency include fall history on admission, any falls since admission or prior assessment, and number of falls since admission or prior assessment.

Intervention Strategies

Individuals with a vitamin D deficiency with limited mobility, are nonambulatory, and/or who are near the end of life may not benefit from vitamin D supplementation. However, individuals who remain active will benefit from improved vitamin D status.

In a healthcare setting, there are several areas in which nutrition services can address vitamin D:

• Work with the RD and physician to provide vitamin D and calcium supplementation.
• Follow up with nursing to be sure the vitamin D and calcium supplements are accepted and well tolerated. Calcium supplements may contribute to constipation in some individuals. Additional dietary fiber and increased fluids may help with the constipation.
• Ask your food vendor for a list of vitamin D fortified foods.
• Provide more foods on your menus that are fortified with vitamin D.
• Work with Nursing, Activities Program, and families to identify opportunities for residents to have more sun exposure.

Improving vitamin D status takes a team effort. Changes in dietary intake, use of vitamin D and calcium supplements, and increased sun exposure will improve vitamin D status over time.

By Mary Litchford, PhD, RD, LDN

Mary Litchford, PhD, RD, LDN is a nationally recognized speaker and the author of Protein Powders, Potions & Elixers.