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What we should know about Vitamin D?

What we should know about Vitamin D?

Professor Sunil Wimalawansa, M.D., Ph.D., M.B.A., F.A.C.E., F.A.C.P., FRCPath., DSc

Professor Sunil Wimalawansa, M.D., Ph.D., M.B.A., F.A.C.E., F.A.C.P., FRCPath., DSc

What we should know about Vitamin D?

Vitamin D – Why do we need and how much we need?

Frontier Voice of Nutrition Remarks (February 23, 2012)

Nalin Siriwardhana, PhD, interviewed Professor Sunil Wimalawansa, M.D., Ph.D., M.B.A., F.A.C.E., F.A.C.P., FRCPath., DSc, Professor of Endocrinology, Metabolism & Nutrition from the University of Medicine and Dentistry, Robert Wood Johnson Medical School, New Jersey, USA.

Most of us have a vitamin D deficiency and do not even know. Some people are severely vitamin D deficient and still go undiagnosed. Severe vitamin D deficiency can lead to many health complications and is NOT something that we can just neglect. Vitamin D deficiency is more common in elderly populations, as well as in children, and adults suffering from diseases including cancer.

There may be multiple reasons for vitamin D deficiency, but it is predominantly due to inadequate sun-exposure. Most patients who need vitamin D supplements are either not given or provide inadequate doses. Moreover, long-term adherence (taking the drug properly) to oral vitamin D supplementation is poor.

Professor Sunil Wimalawansa, M.D., Ph.D., M.B.A., a prominent senior scientist in the field of Endocrinology, Metabolism, and Nutrition, believes that vitamin D deficiency is one of the most under-diagnosed and perhaps one of the most common medical conditions in the world. Many estimate that more than two billion people worldwide, across all ethnic and age groups have vitamin D deficiency (25-hydroxy vitamin D [25(OH)D] levels in the blood, below 20 ng/mL, or 50 nMol/L). Many individuals in industrialized countries, especially in the northern hemisphere, have low serum vitamin D levels. He believes that the recent literature on vitamin D is full of controversies on its measurements, diagnosis, benefits, and the management of deficiency. Nutrition Remarks interviewed Prof. Wimalawansa and a simplified version of the conversation is given below:

Question from Nutrition Remarks: What are the reasons that we need adequate amounts of vitamin D?

Answer from Dr. Wimalawansa: Severe vitamin D deficiency leads to rickets in childhood and osteomalacia in adults. Low vitamin D levels may precipitate and/or aggravate a variety of skeletal and non-skeletal disorders including cancer, diabetes, metabolic syndrome, infectious diseases, and autoimmune disorders. In addition to enhancing calcium absorption from the intestine and mineralization of the osteoid tissue, vitamin D is important in many other physiological effects, including neuro-modulation, muscle strength and coordination, release of insulin, and immune health. For example, cardiovascular morbidity and mortality are increased in patients with all levels of renal dysfunction, especially in those with low serum vitamin D levels.

Vitamin D levels in the body is commonly measured using serum 25(OH)D concentrations. Inadequate serum 25(OH)D concentrations are associated with decreased performance and an increased propensity to falls and fractures secondary to muscle weakness and poor neuromuscular coordination.

Question: Why is vitamin D deficiency common around the world including the US?

Answer: Ultraviolet rays should provide more than 80% of our vitamin D requirement; diet and supplements can augment it. The two major causes of vitamin D deficiency are the lack of exposure to sunlight and less than adequate dietary intakes.

Question: What are the main health issues associated with vitamin D deficiency?

Answer: Widespread vitamin D deficiency may be related to the increasing incidences of cancer, type 2 diabetes, and obesity. The effect of vitamin D on heart disease remains to be determined. The relationship of vitamin D to the skeletal disorders is well-established. However, its relationships to non-skeletal systems and the significance of non-classic functions and targets of vitamin D need further studies.

Question: How do you know if someone is vitamin D deficient and how do you describe serum levels of 25-hydroxyvitamin D [25(OH)D] greater than 30 ng/mL (75 nmol/L) to public?

Answer: There is compelling scientific and epidemiologic data suggesting that humans require a minimum blood level of 25(OH)D 30 ng/mL (75 nmol/L) for satisfactory health. Although controversy exists of the definition of low normal vitamin D status, there is increasing agreement that the lower limit of the circulating 25(OH)D level is to be approximately 30 to 32 ng/mL. Due to the high safety margin and the variability in measurements of serum 25(OH)D levels, to assure adequate serum vitamin D levels, aiming to achieve a value around 40 ng/ml would be useful. Currently, we believe that the optimum serum vitamin D level is between 30 and 40 ng/mL (75 to 100 nMol/L). Levels up to 60 ng/mL (150 nmol/L) are safe and in fact seems to be necessary to obtain the non-skeletal beneficial effects of vitamin D.

Question: What is your advice to people who normally do not receive enough natural sun exposure to produce vitamin D?

Answer: Obtaining vitamin D via diet is not easy. Only fatty fish, like salmon and mackerel, and liver-preparations have high amounts of vitamin D. Among the vegetables, irradiated mushrooms have the high contents of vitamin D. Leaving mushrooms in the sunshine for two hours prior to cooking, can triple its vitamin D content.

An additional 1,000 IU of vitamin D/day is generally sufficient for lighter-skinned individuals, whereas older people and dark-skinned individuals may need an extra 2,000 IU/day to maintain normal serum 25-hydroxyvitamin D [25(OH)D] levels, of over 30 ng/nL (50 nmol/L).

Compliance improves with supplementation of high-strength vitamin D 50,000 twice a month, or 100,000 IU doses administered once a month. Because of the relatively shorter half live/retention in the body, giving higher doses of vitamin D less frequently than once a month will not benefit our patients. Such a maintenance dose can be commenced following a therapeutic loading dose of 50,000 IU of vitamin D given once or twice a week for few weeks to bring the serum vitamin D levels to normal range. These doses are efficacious and safe in replenishment of vitamin D storage in the body and maintaining optimal serum 25(OH)D levels. American endocrine society guidelines indicate the upper safety limit of intake of vitamin D as 10,000 IU/day.

Question: What is your advice to people who have diseases (obesity, cancer and digestive problems) that can reduce vitamin D levels in the body?

Answer: Although no consensus exists, many endocrinologists and bone specialists prefer to keep their patients’ serum vitamin D levels between 30 and 40 ng/mL (75 to 100 nmol/L), or higher. People with intestinal diseases, obese people, and those who have had bariatric surgery have constant difficulty in maintaining serum vitamin D levels; they need higher intakes of vitamin D frequently; daily or weekly basis.

Question: How should pregnant mothers handle vitamin D?

Answer: Vitamin D deficiency during pregnancy has serious consequences for both the mother and the fetus. Changes in vitamin D metabolism can also occur during pregnancy. An increase in the maternal plasma 1,25(OH)2D levels are thought to be due to placental synthesis of the hormone. Placental transfer of vitamin D from mother to fetus is essential for establishing the newborn’s growth; the goal of ensuring adequate vitamin D status with prenatal vitamin D supplements should be encouraged. Pregnant mothers with low 25(OH)D levels also have an increased risk of preeclampsia (swelling, high blood pressure and protein excretion in urine). Therefore, supplementation is important during pregnancy, but not essential during lactation period.

Question: What are the good food sources for vitamin D?

Answer: Vitamin D is present in some foods including mushrooms, cod-liver oil, and fatty fish such as herring, mackerel, sardines, and tuna. Most other food have little vitamin D. To make vitamin D more widely available, in several countries the vitamin is added to dairy products, juices, and breakfast cereals. For developing countries, the recommended food fortification levels can be safely doubled. A healthy diet should contain a variety of fruits and vegetables (five servings a day), whole grains, and fat-free or low-fat milk and milk products.

Question: How can supplements help maintain adequate vitamin D levels?

Answer: In dietary supplements and fortified foods, vitamin D is provided as either as D2 or D3. The two forms are considered as equivalent based on their ability to cure rickets and improving bone histology. Many supplements have been reformulated to contain vitamin D3 instead of vitamin D2. In the absence of rigorous comparative studies, both forms (as well as vitamin D in foods) are considered equally effective in increasing serum 25(OH)D levels. Since retention time of vitamin D3 in the body is higher than vitamin D2, the former is preferred as supplement.

Question: What is vitamin D toxicity and how common is it?

Answer: Humans have sophisticated built-in system to control the generation of active form of vitamin D. Therefore, excessive sun exposure will not cause vitamin D toxicity. Hypervitaminosis D is extremely rare, but can be a potentially serious problem. It can cause kidney damage, growth retardation, calcification of soft tissues, and even death. Vitamin D toxicity may manifest as a variety of non-specific symptoms, including nausea, vomiting, and constipation, loss of appetite, dry mouth, metallic taste, fatigue, sleepiness, headaches, weakness, irritability, and weight loss. Most of these signs and symptoms are due to raised blood calcium levels. . Daily doses consumed over 15,000 IU regularly can lead to vitamin D toxicity.

Question: What are the most important research areas that scientists should do more work on vitamin D?

Answer: We need more controlled clinical studies on dose-responses of vitamin D and correlations with the serum 25(OH) D levels achieved following supplementation with vitamin D. We also need properly conducted controlled clinical studies with reference to non-skeletal outcomes such as cancer, heart disease, all-cause deaths, etc.

Question: What is important information that we did not discuss here?

Answer: Low vitamin D levels may aggravate a variety of non-skeletal disorders including cancer, diabetes, metabolic syndrome, infectious diseases, and autoimmune disorders. While we wait for such studies which may take 10 years or more, it is rational to advice physicians to keep their patients serum vitamin D levels above 30 ng/mL (75 nmol/L) that we currently believe will reduce the disease burden of our patients.

This news release was based on the original scientific article published by Prof. Wimalawansa in Current Osteoporosis Reports journal. (2012). Additional general background information was acquired from PubMed and NIH sources.

Original work; Wimalawansa Sunil, Vitamin D in the New Millennium, Current Osteoporosis Reports. 2012; 10 (1) 4-15.

Professor Sunil Wimalawansa is a University Professor, Professor of Medicine, Endocrinology, Metabolism, and Nutrition, and the former Chief of Endocrinology at the University of Medicine and Dentistry, Robert Wood Johnson Medical School, New Jersey, USA. He is also a Professor of Physiology and Integrative Biology at the University of Medicine and Dentistry, Graduate School Biomedical Sciences. He holds an Executive Master’s of Business Administration Degree from the Rutgers University School of Business and a Diploma in Medical Administration from Johns Hopkins School of Business.

He had his education at Ananda College, Colombo and postgraduate studies at the University of Peradeniya in Sri Lanka, Royal Postgra­duate Medical School in United Kingdom, Rutgers and Johns Hopkins Universities in the United States. He is a member or a board director of several committees of national and international scientific societies. He is the founder-president of several charitable organizations, including the International Foundation for Revitalization, Empowerment, Education, and Development; Hela Empowerment Foundation–International; International Foundation for Chronic Disabilities; and the chairperson of the Education Trust Fund for Needy Children, and the Wimalawansa Charitable Foundation.

His original contributions to science and medicine include current worldwide practiced standard of care in some medical methods. He holds 6 medical patents, and has given more than 170 invited presentations at national and international scientific and medical meetings. He has published over 130 peer-reviewed scientific articles, 4 medical books, and 45 scientific book chapters; and has made 260 scientific presentations worldwide.

Dr. Wimalawansa is the recipient of many awards including Dr. Oscar Gluck International Humanitarian award in 2007, and the prestigious Lifetime Achievement Award in 2005 from the Sri Lankan Foundation for his worldwide contributions to science, philanthropic work, and humanity. Other awards he received include an International Award for Clinical Excellence in Metabolic Bone Diseases in 1991, multiple young-investigator scientific awards, and American Endocrine Society Glen Foundation Awards. He is also the recipient of The Doctor of Science (D.Sc.) degree in 2001.

More about Prof. Wimalawansaand work






Prof. Wimalawansa does not have conflicts of interest, except he has published a book for primary care physicians on vitamin D; title “Vitamin D: Everything you need to know” (Publisher, Karu & Sons, Homagama), 2012.

Written by Nalin Siriwardhana, PhD. and Amanda Fields

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