News Release Distributed 05/11/10
Studies show many older adults are not getting enough vitamin D. Together with calcium, vitamin D helps protect older adults from osteoporosis, says LSU AgCenter nutritionist Beth Reames.
“Vitamin D helps the body absorb and use calcium to build strong bones and teeth and maintain muscle strength,” Reames says. “Without sufficient vitamin D, bones can become thin, brittle or misshapen.”
Vitamin D is called the “sunshine vitamin” because you can get it from being out in the sun, Reames says.
“The body makes Vitamin D when skin is exposed to sunlight's UV rays, and most people meet their vitamin D needs that way,” Reames says.
Vitamin D also plays a role in maintaining the body’s immune function and reducing inflammation, she adds. Recent research suggests that a lack of vitamin D may also play a role in reducing risk of certain types of cancer, diabetes, cardiovascular disease, autoimmune disease and obesity.
Reames says good food sources of vitamin D include vitamin D-fortified milk and orange juice, fortified breakfast cereals, fatty fish such as salmon, mackerel, tuna and sardines, and fish oils, especially cod liver oil. Small amounts of vitamin D are found in beef liver and egg yolks.
The Dietary Reference Intake recommendation for vitamin D is measured in international units – IUs – and increases with age. People younger than 50 years old, including pregnant and lactating women, need 200 IUs, Reames says. People between 50 and 70 need 400 IUs, and those over 70 need at least 600 IUs each day.
Although a suggested recommendation to meet vitamin D needs is approximately five to 30 minutes of sun exposure between 10 a.m. and 3 p.m. at least twice a week, excessive sun exposure should be avoided. The American Academy of Dermatology advises that protective measures, such as using sunscreen, be taken whenever one is exposed to the sun.
“Increasing age and having dark skin decrease the body’s ability to make vitamin D from sun exposure,” Reames says. “At age 70, vitamin D production is only 30 percent of what it was at age 25.”
The 2005 Dietary Guidelines recommends that older adults, people with dark skin and people with insufficient exposure to sunlight should consume extra vitamin D – about 1,000 IUs – from vitamin D-fortified foods or supplements.
Because vitamin D is fat-soluble and is stored in the body, it could become toxic at high levels, the dietitian says. This toxicity is more likely to occur from too much dietary supplement rather than from too much vitamin D-fortified foods and does not occur with excessive sun exposure. The recommended upper limit of vitamin D from foods and supplements is 1,000 IUs a day for those younger than one year old and 2,000 IUs a day for others.
Experts have suggested possible links between vitamin D and certain chronic diseases, including the following:
– Osteoporosis. More than 25 million U.S. adults have or are at risk of developing osteoporosis, a disease characterized by fragile bones that significantly increases the risk of bone fractures. Osteoporosis is most often associated with inadequate calcium intake, but insufficient vitamin D contributes to osteoporosis by reducing calcium absorption. A recent report concluded that supplements of both vitamin D3 at 700-800 IUs a day and calcium at 500-1,200 milligrams a day decreased the risk of falls, fractures and bone loss in elderly individuals 62-85 years old.
– Cardiovascular disease. Studies suggest that low levels of vitamin D may adversely affect the cardiovascular system and that treating vitamin D deficiency could reduce cardiovascular risk. Vitamin D promotes healthy vascular smooth muscles and the inner lining of blood vessels.
– Cancer. A growing body of evidence shows vitamin D may have helpful effects on some types of cancer. According to the National Cancer Institute, some studies suggest higher intakes of vitamin D and higher levels of vitamin D in the blood are associated with reduced risks of colorectal cancer, though overall research results have been inconsistent.
The National Cancer Institute does not recommend vitamin D supplements to reduce the risk of colorectal or any other type of cancer, Reames says.
– Diabetes. Vitamin D deficiency has been observed to impair both insulin synthesis and insulin secretion. It may play a role in development of metabolic syndrome and type 2 diabetes.
Metabolic syndrome is a condition associated with increased risk of heart disease and diabetes.
Type 1 diabetes is an autoimmune disease that occurs when the body launches an immune response and destroys the insulin-producing cells in the pancreas. Evidence suggests vitamin D may enhance immunity and offer protection against various autoimmune diseases. Other autoimmune diseases that have been suggested as having links to vitamin D deficiencies include multiple sclerosis and rheumatoid arthritis.
“Currently, routine vitamin D supplementation for people with diabetes has not been recommended,” Reames says.
– Obesity. Studies have shown that obesity, higher waist circumference and higher serum insulin are associated with low blood levels of vitamin D. Obesity does not affect the skin's capacity to make synthesize vitamin D, but greater amounts of body fat hold more of the vitamin and alter its release into the blood.
“Most evidence for the role of vitamin D in disease prevention is based on laboratory, animal and epidemiological studies,” Reames says. “Randomized clinical trials are needed to provide definitive data for establishing public health and patient care recommendations.”
Reames points out that the 2005 Dietary Guidelines for Americans says, “nutrient needs should be met primarily through consuming foods. Foods provide an array of nutrients and other compounds that may have beneficial effects on health. In certain cases, fortified foods and dietary supplements may be useful sources of one or more nutrients that otherwise might be consumed in less than recommended amounts. However, dietary supplements, while recommended in some cases, cannot replace a healthful
diet.”
Rick Bogren