OSTEOPOROSIS & VITAMIN D DEFICIENCY & HOMOEOPATHY

1. OSTEOPOROSIS & VITAMIN D DEFICIENCY& HOMOEOPATHY BY DR SANJEEV AGGARWAL MEDICAL OFFICER ON CONTRACT BASIS DTE OF ISM & HOMOEOPATHY,GOVT OF DELHI

2. Osteoporosis - An Overview OSTEOPOROSIS IS DEFINED AS"A DISEASE CHARACTERIZED BY LOW BONE MASS, MICROARCHITECTURAL DETERIORATION OF BONE TISSUE, OR BOTH, LEADING TO SKELETAL FRAGILITY." OSTEOPENIA IS A PRECURSOR TO OSTEOPOROSIS

3. Epidemiology OSTEOPOROSIS AFFECTS AN ESTIMATED 30 PERCENT OF POSTMENOPAUSAL WHITE AND ASIAN WOMEN IN THE U.S. RATES ARE LOWER, THOUGH NOT INCONSEQUENTIAL, AMONG OTHER GROUPS: APPROX. 10 PERCENT OF AFRICAN AMERICAN WOMEN AND 13 TO 16 PERCENT OF HISPANIC WOMEN AGE 50 AND OLDER HAVE OSTEOPOROSIS.HIP FRACTURES OCCUR IN 15 PERCENT OF ELDERLY WOMEN. ONLY ONE-THIRD OF HIP-FRACTURE PATIENTS WILL RETURN TO PRE-FRACTURE INDEPENDENCE.

4. AS OUR POPULATION AGES, THE NUMBER OF HIP FRACTURES IS EXPECTED TO TRIPLE BY 2040.LONG-TERM SEQUELAE INCLUDE FRACTURES OF HIP, SPINE, WRIST, RIBS, ETC.; CHRONIC FRACTURE PAIN; AND COMPRESSION OF INTERNAL ORGANS FROM REPEATED VERTEBRAL COMPRESSION FRACTURES AND KYPHOSIS.AS WITH POST-MENOPAUSAL WOMEN, HYPOGONADISM IN MEN MAY ACCELERATE BONE LOSS. CORTICOSTEROID THERAPY, SEVERE HYPERTHYROIDISM, AND HYPERPARATHYROIDISM CAN ALSO CAUSE RAPID BONE LOSS.

5. Risk Factors AgeFamily history of fracture in first-degree relative (particularly prior to age 80) Personal history of fracture after age 40 Current cigarette smoking

6. Prevention Peak bone mass is reached in the late twenties for women, mid-thirties for mendaily allowances of calcium and vitamin D IS AS:

7. CALCIUM AGE RECOMMENDED DAILY INTAKEINFANTS 0 TO 6 MONTHS 200 MGINFANTS 6 TO 12 MONTHS 260 MGCHILDREN 1-3 YEARS OLD 700 MGCHILDREN 4-8 YEARS OLD 1000 MGCHILDREN & YOUNG ADULTS 9-18 YRS 1300 MGADULTS 19-50 YEARS 1000 MGWOMEN AND MEN OVER 50 YEARS 1200 MG

8. VITAMIN D AGE RECOMMENDED DAILY INTAKEBIRTH TO 11 MONTHS 400 IUAGES 1 TO 70 YEARS 600 IUAGE 70 AND OVER 800 IU

9. Symptoms & Diseases Associated With Vitamin D Deficiency It is estimated that anywhere from 30 to 100% of Americans, depending upon their age and community living environments, are deficient in Vitamin D. More than half of all American children are vitamin deficient. Supposedly almost 3/4s of pregnant women are vitamin D deficient, predisposing their unborn children to all sorts of problems. Worldwide, it is estimated that the epidemic of vitamin D deficiency affects one billion people. It is clinically observed that over 80% of patients whose vitamin D levels are deficient.

10. The flu: vitamin D deficiencypredisposes children to respiratory diseases; study conducted showed that vitamin D reduces the incidence of respiratory infections in children. Muscle weakness: muscle weakness is usually caused by vitamin D deficiency because for skeletal muscles to function properly, their vitamin D receptors must be sustained by vitamin D. Psoriasis: synthetic vitamin D analogues were found useful in the treatment of psoriasis. Chronic kidney disease: patients with advanced chronic kidney diseases (especially those requiring dialysis) are unable to make the active form of vitamin D.

11. Diabetes: 10,366 children were given 2000 international units (IU)/day of vitamin D3 per day during their first day of life. The children were monitored for 31 years and in all of them, the risk of type 1 diabetes was reduced by 80 percent. Asthma: Vitamin D may reduce the severity of asthma attacks. Periodontal disease: Those suffering from this chronic gum disease that causes swelling and bleeding gums should consider raising their vitamin D levels to produce defensins and cathelicidin, compounds that contain microbial properties and lower the number of bacteria in the mouth.

12. Cardiovascular disease: women with low vitamin D levels (17 ng/m [42 nmol/L]) had a 67 percent increased risk of developing hypertension. Schizophrenia and Depression: it was discovered that maintaining sufficient vitamin D among pregnant women and during childhood was necessary to satisfy the vitamin D receptor in the brain integral for brain development and mental function maintenance in later life. Cancer: increased doses of the sunshine vitamin were linked to a 75 percent reduction in overall cancer growth and 50 percent reduction in tumor cases among those already having the disease, vitamin D supplementation to help control the development and growth of breast cancer specially estrogen-sensitive breast cancer.

13. How much vitamin D do I need ? If your blood level is above 45ng/ml and for maintenance, I recommend 2,000-4,000 IU daily depending on age, weight, season, how much time is spent outdoors, where one lives, skin color and obviously blood levels. In other words if you are older, larger, living in the northern latitudes during the winter, are not getting sun and have dark skin, I recommend the higher maintenance dose. If your blood level is 35-45 ng/ml, I recommend you correct it with 5,000 of vitamin D3 a day for 3 months under a doctor’s supervision and then recheck your blood levels. If your blood level is less than 35 ng/ml, I recommend you correct it with 10,000 of vitamin D3 a day under a doctor’s supervision and then recheck your blood levels after 3 months. It takes a good 6 months usually to optimize your vitamin D levels if you’re deficient. Once this occurs, you can lower the dose to the maintenance dose of 2,000 – 4,000 IU a day.

14. What are the symptoms of vit D deficiency? There is no clear pattern of symptoms. In fact many people remain asymptomatic despite low levels. But here are common symptoms Fatigue General muscle pain and weakness Muscle cramps Joint pain Chronic pain Weight gain High blood pressure Restless sleep Poor concentration Headaches Bladder problems Constipation or diarrhea

15. Diseases associated with Vitamin D deficiency Osteoporosis and Osteopenia 17 varieties of Cancer (including breast, prostate and colon) Heart disease High blood pressure Obesity Metabolic Syndrome and Diabetes Autoimmune diseases Multiple sclerosis Rheumatoid arthritis Osteoarthritis Bursitis Gout Infertility and PMS Parkinson’s Disease Depression and Seasonal Affective Disorder Alzheimer’s Disease Chronic fatigue syndrome Fibromyalgia Chronic Pain Periodontal disease Psoriasis

17. Individuals at High Risk for Vitamin D Deficiency Individuals most likely to have vitamin D deficiency are those who do not take supplements, are elderly, are darkly pigmented, are obese, have osteoporosis or osteopenia, avoid any sun exposure without sunscreen, are typically veiled,live in a highly polluted environment,or have Crohn's disease or other reasons for fat malabsorption.

18. Recommendations for Treatment of Vitamin D Deficiency or Insufficiency Serum 25(OH)D Level (ng/mL) 20-30 ; 12-20 ; < 12 (asymptomatic) Vitamin D3 Suppl Dose (IU) 1,000-2,000 2,000 4,000-5,000 Frequency of Vitamin D Supplementation Daily < 12 (symptomatic) 30,000 weekly

19. Why do we need vitamin D? A main action of vitamin D is to help calcium and phosphorus in our diet to be absorbed from the gut. Calcium and phosphorus are needed to keep bones healthy and strong. So, vitamin D is really important for strong and healthy bones. In addition, vitamin D seems to be important for muscles and general health. There is also some evidence that vitamin D may also help to prevent other diseases such as cancer, diabetes and heart disease.

20. Where the body is unable to make enough vitamin D This can occur for various reasons: People who get very little sunlight on their skin are at risk of vitamin D deficiency. This is more of a problem in the more northerly parts of the world (including the UK)  where there is less sun. In particular: People who stay inside a lot. For example, those in hospital for a long time, or housebound people. People who cover up a lot of their body when outside. For example, wearing veils such as the niqab or burqa. Strict sunscreen use can potentially lead to vitamin D deficiency, particularly if high sun protection factor (SPF) creams (factor 15 or above) are used. Nevertheless, children especially should always be protected from the harmful effect of the sun's rays and should never be allowed to burn or be exposed to the strongest midday sun.

21. Elderly people have thinner skin than younger people and so are unable to produce as much vitamin D. This leaves older people more at risk of vitamin D deficiency. People who have darker skin. For example people of African, African-Caribbean and South Asian origin, because their bodies are not able to make as much vitamin D. Some medical conditions can affect the way the body handles vitamin D. People with Crohn's disease, coeliac disease, and some types of liver and kidney disease, are all at risk of vitamin D deficiency. Rarely, some people without any other risk factors or diseases become deficient in vitamin D. It is not clear why this occurs. It may be due to a subtle metabolic problem in the way vitamin D is made or absorbed. So, even some otherwise healthy, fair-skinned people who get enough sun exposure can become deficient in vitamin D. Vitamin D deficiency can also occur in people taking certain medicines. Examples include: carbamazepine, phenytoin, primidone, barbiturates and some anti-HIV medicines.

22. How common is vitamin D deficiency? It is very common. A recent survey in the UK showed that more than half of adults in the UK did not have enough vitamin D. In the winter and spring about 1 in 6 people have a severe deficiency. It is estimated that about 9 in 10 adults in the UK of South Asian origin may be vitamin D-deficient. Most affected people either don't have any symptoms, or have tiredness or vague aches and pains, and are unaware of the problem.

23. What are the symptoms of vitamin D deficiency? Many people have no symptoms, or only vague ones such as tiredness or general aches. Because symptoms of vitamin D deficiency are often very nonspecific or vague, the problem is often missed. The diagnosis is more easily reached in severe deficiencies with some of the classical (typical) symptoms and bone deformities.

24. Cautions when taking vitamin D supplements Care is needed with vitamin D supplements in certain situations: If you are taking certain other medicines: digoxin (for an irregular heartbeat - atrial fibrillation) or thiazide diuretics such as bendroflumethiazide (commonly used to treat high blood pressure). In this situation, avoid high doses of vitamin D, and digoxin will need monitoring more closely. If you have other medical conditions: kidney stones, some types of kidney disease, liver disease or hormonal disease. Specialist advice may be needed. Vitamin D should not be taken by people who have high calcium levels or certain types of cancer. You may need more than the usual dose if taking certain medicines which interfere with vitamin D. These include: carbamazepine, phenytoin, primidone, barbiturates and some medicines for the treatment of HIV infection.

25. The outlook is usually excellent. Both the vitamin levels and the symptoms generally respond well to treatment. However, it can take time (months) for bones to recover and symptoms such as pain to get better or improve.The complications of severe deficiency have been mentioned. Rickets can occur in children, and osteomalacia in adults. These diseases affect the strength and appearance of bones, and can lead to permanent bone deformities if untreated or if treatment is delayed.Vitamin D has been linked to other diseases. In recent years there have been associations with conditions such as cancer, heart disease, infectious disorders, autoimmune disease and diabetes. This does not mean that all people with vitamin D deficiency will get these problems. Nor does it mean that if you have one of these illnesses, a vitamin D deficiency is the cause. In these cases, vitamin D is thought to be just one factor.

26. How Does Vitamin D Protect Against Radiation-Induced Damage? Scientists have identified a total of nearly 3,000 genes that are upregulated by vitamin D, so it makes sense that it would have "multifaceted protective actions," as researchers noted in the International Journal of Low Radiation. The report found that the most active molecular form of vitamin D -- D3 (also known as calcitriol) -- may offer protection against a variety of radiation-induced damages, including those caused by background radiation or a low-level nuclear incident, through the following mechanisms: Cell cycle regulation and proliferation Cellular differentiation and communication Programmed Cell Death (PCD) Anti-angiogenesis (a process that stops tumors from making new blood vessels, which means they stop growing)

27. Three Points to Remember About Vitamin D When using vitamin D therapeutically, it's important to remember the following: Your best source for vitamin D is exposure to the sun, without sun-block on your skin, until your skin turns the lightest shade of pink. While this isn't always possible due to the change of the seasons and your geographic location (and your skin color), this is the ideal to aim for. Vitamin D supplementation or use of a safe tanning bed can fill the gaps during the winter months outside of the tropics, when healthy sun exposure is not an option. If you supplement with vitamin D, you'll only want to supplement with natural vitamin D3 (cholecalciferol). Do NOT use the synthetic and highly inferior vitamin D2. Get your vitamin D blood levels checked! The only way to determine the correct dose is to get your blood tested since there are so many variables that influence your vitamin D status.

28. Factors influence skin synthesis of vitamin D SKIN SYNTHESIZES VITAMIN D WHEN EXPOSED TO SUNLIGHT (UVB RADIATION), WHICH IS USUALLY SUFFICIENT TO MEET THE DAILY REQUIREMENTSSKIN PRODUCTION OF VITAMIN D3 DECREASES WITH AGE BEGINNING IN THE THIRD DECADETHE 25-OH VITAMIN D3 LEVELS WERE THREE TIMES LOWER IN ELDERLY PEOPLE AGE 62 TO 80 THAN IN PEOPLE AGE 22 TO 30 GIVEN THE SAME SUNLIGHT EXPOSURE

29. variation in vitamin D synthesis occurs because sunlight exposure and UVB radiation absorption vary with degree of skin pigmentation, season, latitude, time of day, atmospheric conditions, and duration of exposurevitamin D synthesis is significantly decreased and sometimes completely stopped by the application of sunscreenchronic use of sunscreens can reduce serum vitamin D levels

30. CLOTHING, GLASS, PLASTIC, AND PLEXIGLAS ALSO PREVENT UVB RADIATION ABSORPTIONDARK SKIN PIGMENTATION MAKES INDIVIDUALS MORE VULNERABLE TO VITAMIN D DEFICIENCY AS MELANIN BLOCKS ABSORPTION OF UVB RADIATIONIN DEVELOPED COUNTRIES, FORTIFICATION OF DAIRY PRODUCTS WITH VITAMIN D HAS REDUCED THE INCIDENCE OF OSTEOMALACIA

31. VITAMIN D IS CRUCIAL TO NORMAL BONE GROWTH AND DEVELOPMENTWHEN UV LIGHT SHINES ON A LIPID PRESENT IN SKIN CELLS, THE COMPOUND IS TRANSFORMED INTO VITAMIN DPEOPLE NATIVE TO EQUATORIAL AND LOW LATITUDE REGIONS OF THE EARTH HAVE DARK SKIN PIGMENTATION AS A PROTECTION AGAINST STRONG, NEARLY CONSTANT EXPOSURE TO UV RADIATION

32. INCREASED MELANIN PIGMENTATION, PRESENT IN PEOPLE NATIVE TO LOWER LATITUDES, REDUCES THE PRODUCTION OF VITAMIN DTHE DOSE OF ULTRAVIOLET LIGHT REQUIRED TO STIMULATE SKIN SYNTHESIS OF VITAMIN D IS ABOUT SIX TIMES HIGHER IN AFRICAN AMERICANS THAN IN PEOPLE OF EUROPEAN DESCENTSUSCEPTIBILITY TO VITAMIN D DEFICIENCY IS INCREASED IN THESE POPULATIONS BY THE TRADITIONAL CLOTHING OF MANY CULTURAL GROUPS NATIVE TO LOW LATITUDES

33. What is used to to synthesize Vitamin D in skin cells? Sun exposure and cholesterol. Sun exposure converts 7-dehydrocholesterol to previtamin D3, which is then converted to Vitamin D. Does Skin Synthesize Vitamin D?Yes. In presence of ultraviolet rays cholesterol in blood is converted into vitamin D. Which gets one hydrogen atom attached in liver and another in kidney to from active form of vitamin D

34. What Part of the skin synthesizes vitamin D? The Stratum Spinosum and Basale from the Epidermis. What activates the skin to start process of producing Vitamin D? vitamin c When might skin not be able to produce enogh vitamin D? when the skin has not absorbed sufficent sunlight specifiallyu.v rays

35. Sun Protection Practices AVOID SUN BURNING, INTENTIONAL TANNING, AND USING TANNING BEDS.APPLY SUNSCREEN GENEROUSLY.WEAR SUN-PROTECTIVE CLOTHING, WIDE-BRIMMED HAT, AND SUNGLASSES.SEEK SHADE.USE EXTRA CAUTION NEAR WATER, SNOW, AND SAND.GET VITAMIN D THROUGH DIET AND VITAMIN D SUPPLEMENTS.

36. IOM Recommendation on Vitamin D Recommended Dietary Allowances (RDAs)*:0- 12 mo: 400 IU/d1- 70 yrs: 600 IU/d **71+ yrs: 800 IU/d* Covering the requirements of ≥ 97.5% of population** Includes pregnant and nursing women

37. Sunlight exposure is the primary source of vitamin D for most people. Solar ultraviolet-B radiation (UVB; wavelengths of 290 to 315 nanometers) stimulates the production of vitamin D3 from 7-dehydrocholesterol (7-DHC) in the epidermis of the skin vitamin D is actually more like a hormone than a vitamin, a substance that is required from the diet. Vitamin D3 enters the circulation and is transported to the liver, where it is hydroxylated to form 25-hydroxyvitamin D3 (calcidiol; the major circulating form of vitamin D). In the kidneys, the 25-hydroxyvitamin D3-1-hydroxylase enzymecatalyzes a second hydroxylation of 25-hydroxyvitamin D, resulting in the formation of 1,25-dihydroxyvitamin D3 (calcitriol, 1alpha,25-dihydroxyvitamin D]—the most potent form of vitamin D

38. Vitamin D Miracles Sunlight and vitamin D are critical to all life forms. The principal function of vitamin D is to promote calcium absorption in the gut and calcium transfer across cell membranes, thus contributing to strong bones and a calm, contented nervous system. It is also well recognized that vitamin D aids in the absorption of magnesium, iron and zinc, as well as calcium. Actually, vitamin D does not in itself promote healthy bone. Vitamin D controls the levels of calcium in the blood. If there is not enough calcium in the diet, then it will be drawn from the bone. High levels of vitamin D (from the diet or from sunlight) will actually demineralize bone if sufficient calcium is not present.

39. Vitamin D will also enhance the uptake of toxic metals like lead, cadmium, aluminum and strontium if calcium, magnesium and phosphorus are not present in adequate amounts. Vitamin D supplementation should never be suggested unless calcium intake is sufficient or supplemented at the same time. Receptors for vitamin D are found in most of the cells in the body and research during the 1980s suggested that vitamin D contributed to a healthy immune system, promoted muscle strength, regulated the maturation process and contributed to hormone production.

40. During the last ten years, researchers have made a number of exciting discoveries about vitamin D. They have ascertained, for example, that vitamin D is an antioxidant that is a more effective antioxidant than vitamin E in reducing lipid peroxidation and increasing enzymes that protect against oxidation. Vitamin D deficiency decreases biosynthesis and release of insulin. Glucose intolerance has been inversely associated with the concentration of vitamin D in the blood. Thus, vitamin D may protect against both Type I and Type II diabetes. The risk of senile cataract is reduced in persons with optimal levels of D and carotenoids.

41. PCOS (Polycystic Ovarian Syndrome) has been corrected by supplementation of D and calcium. Vitamin D plays a role in regulation of both the "infectious" immune system and the "inflammatory" immune system. Low vitamin D is associated with several autoimmune diseases including multiple sclerosis, Sjogren's Syndrome, rheumatoid arthritis, thyroiditis and Crohn's disease. Osteoporosis is strongly associated with low vitamin D. Postmenopausal women with osteoporosis respond favorably (and rapidly) to higher levels of D plus calcium and magnesium. D deficiency has been mistaken for fibromyalgia, chronic fatigue or peripheral neuropathy.

42. Infertility is associated with low vitamin D. Vitamin D supports production of estrogen in men and women. PMS has been completely reversed by addition of calcium, magnesium and vitamin D. Menstrual migraine is associated with low levels of vitamin D and calcium. Breast, prostate, skin and colon cancer have a strong association with low levels of D and lack of sunlight. Activated vitamin D in the adrenal gland regulates tyrosine hydroxylase, the rate limiting enzyme necessary for the production of dopamine, epinephrine and norepinephrine. Low D may contribute to chronic fatigue and depression. Seasonal Affective Disorder has been treated successfully with vitamin D. In a recent study covering 30 days of treatment comparing vitamin D supplementation with two-hour daily use of light boxes, depression completely resolved in the D group but not in the light box group.

43. High stress may increase the need for vitamin D or UV-B sunlight and calcium. People with Parkinsons and Alzheimers have been found to have lower levels of vitamin D. Low levels of D, and perhaps calcium, in a pregnant mother and later in the child may be the contributing cause of "crooked teeth" and myopia. When these conditions are found in succeeding generations it means the genetics require higher levels of one or both nutrients to optimize health. Behavior and learning disorders respond well to D and/or calcium combined with an adequate diet and trace minerals.

44. Vitamin D and Heart Disease Research suggests that low levels of vitamin D may contribute to or be a cause of syndrome X with associated hypertension, obesity, diabetes and heart disease. Vitamin D regulates vitamin-D-binding proteins and some calcium-binding proteins, which are responsible for carrying calcium to the "right location" and protecting cells from damage by free calcium. Thus, high dietary levels of calcium, when D is insufficient, may contribute to calcification of the arteries, joints, kidney and perhaps even the brain. Many researchers have postulated that vitamin D deficiency leads to the deposition of calcium in the arteries and hence atherosclerosis, noting that northern countries have higher levels of cardiovascular disease and that more heart attacks occur in winter months.

45. Scottish researchers found that calcium levels in the hair inversely correlated with arterial calcium—the more calcium or plaque in the arteries, the less calcium in the hair. Ninety percent of men experiencing myocardial infarction had low hair calcium. When vitamin D was administered, the amount of calcium in the beard went up and this rise continued as long as vitamin D was consumed. Almost immediately after stopping supplementation, however, beard calcium fell to pre-supplement levels. Administration of dietary vitamin D or UV-B treatment has been shown to lower blood pressure, restore insulin sensitivity and lower cholesterol.

46. The Battle of the Bulge Did you ever wonder why some people can eat all they want and not get fat, while others are constantly battling extra pounds? The answer may have to do with vitamin D and calcium status. Sunlight, UV-B, and vitamin D normalize food intake and normalize blood sugar. Weight normalization is associated with higher levels of vitamin D and adequate calcium. Obesity is associated with vitamin-D deficiency. In fact, obese persons have impaired production of UV-B-stimulated D and impaired absorption of food source and supplemental D.

47. When the diet lacks calcium, whether from D or calcium deficiency, there is an increase in fatty acid synthase, an enzyme that converts calories into fat. Higher levels of calcium with adequate vitamin D inhibit fatty acid synthase while diets low in calcium increase fatty acid synthase by as much as five-fold. In one study, genetically obese rats lost 60 percent of their body fat in six weeks on a diet that had moderate calorie reduction but was high in calcium. All rats supplemented with calcium showed increased body temperature indicating a shift from calorie storage to calorie burning (thermogenesis).

48. The Right Fats The assimilation and utilization of vitamin D is influenced by the kinds of fats we consume. Increasing levels of both polyunsaturated and monounsaturated fatty acids in the diet decrease the binding of vitamin D to D-binding proteins. Saturated fats, the kind found in butter, tallow and coconut oil, do not have this effect. Nor do the omega-3 fats. D-binding proteins are key to local and peripheral actions of vitamin D. This is an important consideration as Americans have dramatically increased their intake of polyunsaturated oils (from commercial vegetable oils) and monounsaturated oils (from olive oil and canola oil) and decreased their intake of saturated fats over the past 100 years.

49. In traditional diets, saturated fats supplied varying amounts of vitamin D. Thus, both reduction of saturated fats and increase of polyunsaturated and monounsaturated fats contribute to the current widespread D deficiency. Trans fatty acids, found in margarine and shortenings used in most commercial baked goods, should always be avoided. There is evidence that these fats can interfere with the enzyme systems the body uses to convert vitamin D in the liver.

50. Vitamin D Therapy Single, infrequent, intense, skin exposure to UV-B light not only causes sunburn but also suppresses the immune system. On the other hand, frequent low-level exposure normalizes immune function, enhancing NK-cell and T-cell production, reducing abnormal inflammatory responses typical of autoimmune disorders, and reducing occurrences of infectious disease.26;67;68-71 Thus it is important to sunbathe frequently for short periods of time, when UV-B is present, rather than spend long hours in the sun at infrequent intervals. Adequate UV-B exposure and vitamin-D production can be achieved in less time than it takes to cause any redness in the skin. It is never necessary to burn or tan to obtain sufficient vitamin D.