When you think of vitamin D, you think of the sun. You remember your parents reminding you to put on more sunscreen or to get under the beach umbrella for fear of a brutal sunburn or eventual skin cancer. Vitamin D can be absorbed from the sun as well as select foods or vitamins and is responsible for increasing intestinal absorption of calcium, magnesium and phosphate as well as many other biological effects. While many know vitamin D is necessary, there are many risks that come with too much – or even too little – intake, and the effects are more common than many think. Healthy New Albany Magazine talked with Dr. Mark Bechtel, dermatologist at The Ohio State University Wexner Medical Center, to learn more about deficiency and excess of vitamin D.
Healthy New Albany: Should the average person be consuming vitamin D supplements or do most people typically get the correct amount on their own?
Dr. Mark Bechtel: The need for vitamin D supplementation varies widely from one individual to another. A majority of Americans have adequate vitamin D levels from their diet or sun exposure. The major source of vitamin D is the synthesis in the skin for vitamin D3 after exposure to ultraviolet B radiation from the sun. Vitamin D is not found in many foods. Fortified milk and cereal, salmon, mackerel, canned tuna, eggs, and mushrooms contain vitamin D.
HNA: What are the main causes for vitamin D deficiency and what are the symptoms?
MB: The most accurate way to determine vitamin D deficiency is a blood test. Vitamin D deficiency is defined by some experts as a 25-hydroxy vitamin D level <20ng/ml. Insufficiency of vitamin D is defined as levels between 20-29ng/ml. Individuals with limited sun exposure, living in northern latitudes, wearing head coverings for religious reasons or extensive sunscreen use are at risk of a vitamin D deficiency. Individuals with obesity, malabsorption syndromes, and kidney and liver disease, as well as the elderly, may have decreased vitamin D levels. Darker skin, with its increased melanin pigment, may decrease skin synthesis of vitamin D. Inadequate vitamin D may cause rickets in children, osteomalacia and osteoporosis. The bones become soft, thin and brittle, resulting in greater risk of bone fractures and deformities.
HNA: What are the main causes for vitamin D toxicity, and what are the symptoms?
MB: Vitamin D toxicity is called hypervitaminosis D. A significant elevation in vitamin D causes abnormally high blood levels of calcium. This can cause increased calcification of bones, soft tissues and the heart, as well as kidney stones. This is usually due to mega doses of vitamin D supplements.
HNA: How does the correct amount of vitamin D benefit your body?
MB: Vitamin D plays an important role in the regulation of calcium and phosphorus, which is important for bone health. Adequate vitamin D may help reduce the risk of osteoporosis, which is common in postmenopausal women and older men. There is ongoing research on the impact of vitamin D in diabetes, hypertension, the immune system and cancer.
HNA: How long would it take for someone to be absorbing too much or too little vitamin D for it to have a negative effect on the body?
MB: Excessive or inadequate intake of vitamin D can begin producing negative effects in weeks or months. The adverse effects progress over time.
HNA: How would one reverse the effects of vitamin D deficiency or toxicity?
MB: If vitamin D toxicity occurs, discontinuing or lowering intake of high-dose vitamin D supplements is important. The maximum daily intake of vitamin D that is unlikely to cause health risks is 4,000 International Units (IU) per day. It may be necessary to lower the amount of calcium in the diet. Vitamin D levels will need to be carefully monitored until they are normal. Vitamin D deficiency is carefully managed by a health care provider using diet and vitamin D supplements. Treatment is based on the vitamin D level.
HNA: What is the most frequent problem you see in patients regarding vitamin D?
MB: The most frequent problem I see with my patients is vitamin D deficiency. Due to concerns for skin cancer from sun exposure, many of my patients use sunscreens. The continued use of sunscreens is important for skin cancer prevention, and adequate vitamin D levels can be maintained by diet and supplementation of vitamin D.
HNA: How much vitamin D is the right amount? Why do you think people struggle to get enough/avoid consuming too much?
MB: The Institute of Medicine has published guidelines on adequate daily intake of vitamin D from all sources.
Infants 0-12 months 400 IU
Children 1-18 years 600 IU
Adults 18-70 years 600 IU
Adults over 70 years of age 800 IU
Primary care physicians and specialists often monitor vitamin D levels with routine physical exams. This helps provide guidelines for dietary intake and vitamin D supplements.
HNA: How would a person recognize that he or she is having a problem with vitamin D intake?
MB: It is very difficult to recognize problems with vitamin D intake. The symptoms are very subtle and difficult to recognize. One should consider vitamin D concerns with symptoms of bone pain, muscle weakness, confusion or irritability.
HNA: Is there any advice you have for our readers regarding vitamin D?
MB: Sunlight is an important cause of vitamin synthesis and also skin cancer. Maximum vitamin D synthesis in the skin can occur with only several minutes of sun exposure. Patients with a history of skin cancer or previous sun damage should continue sunscreens and depend on vitamin D supplements and diet for adequate vitamin D levels.
Laura Cole is a contributing writer. Feedback welcome at feedback@cityscenemediagroup.com.
About the Expert
Dr. Mark Bechtel is a professor of medicine and director of the division of dermatology at The Ohio State University College of Medicine. He previously served as chief of dermatology at Nationwide Children’s Hospital.
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