What makes vit d

That's where a sunscreen comes in. Look for a product with an SPF of 30 or higher. Apply your sunscreen early, often, and liberally.

These many factors explain why vitamin D deficiencies are shockingly common in the United States. And low levels of vitamin D are common even in apparently healthy young adults; in one study, more than a third of people between the ages of 18 and 29 were deficient. Numbers can never tell the whole story, but in this case, "D-ficiencies" add up to a wide range of health concerns. It's a paradox: Skeletal health is the best-known contribution of vitamin D, but it has also become the most controversial.

Although doctors agree that vitamin D deficiency increases the risk of osteoporosis and fractures, they disagree about the benefits and optimal dosage of supplements.

Without enough vitamin D, the intestines cannot efficiently absorb calcium. But because blood calcium is critical for neuromuscular and cardiac function, the body does not allow levels to fall.

Instead, it pours out parathyroid hormone, which mobilizes calcium from bone. Blood calcium levels remain normal, so your heart and nerves keep working nicely. But your bones bear the brunt: As bone calcium density falls, bones become weak and fracture-prone. Most studies show that a lack of vitamin D increases the risk of osteoporosis and the likelihood of hip and other non-spinal fractures. But there is considerable disagreement about how much supplements reduce the risk of fractures.

Some studies include only women, others both men and women; some include only frail, elderly, or institutionalized subjects, others physically active people; some use vitamin D alone, others a combination of D and varying doses of calcium; and some administer international units IU of vitamin D a day, others up to IU a day.

Some men mistakenly dismiss osteoporosis as a women's worry, but none fail to recognize the importance of prostate cancer. Vitamin D has an important role in regulating cell growth.

Laboratory experiments suggest that it helps prevent the unrestrained cell multiplication that characterizes cancer by reducing cell division, restricting tumor blood supply angiogenesis , increasing the death of cancer cells apoptosis , and limiting the spread of cancer cells metastasis.

Like many human tissues, the prostate has an abundant supply of vitamin D receptors. And, like some other tissues, it also contains enzymes that convert biologically inactive 25 OH D into the active form of the vitamin, 1,25 OH 2D. These enzymes are much more active in normal prostate cells than in prostate cancer cells. In , Harvard's Health Professionals Follow-up Study of 47, men reported that a high consumption of calcium supplements was associated with an increased risk of advanced prostate cancer.

The risk was greatest in men getting more than 2, mg of calcium a day from a combination of supplements and food. Since then, other studies have confirmed a link between very high levels of calcium intake and increased risk, but they have exonerated dietary calcium consumption. The Harvard scientists speculate that the problem is not calcium itself but a relative lack of active vitamin D. The risk of colon cancer , breast cancer, and other malignancies appears to rise in populations at latitudes far from the equator.

Sun exposure and vitamin D levels may be part of the explanation. A recent clinical trial looking at a daily 1, IU vitamin D supplement did not show a decreased risk of cancer, but it was associated with a decreased risk of cancer death. The most widely used recommended dietary allowance RDA for vitamin D is IU daily for adults up to age 69 and IU daily for people older than Is more better?

Like the other fat-soluble vitamins, vitamin D is stored in the body's adipose fat tissue. That means your body can mobilize its own reserves if your daily intake falters temporarily — but it also means that excessive doses of vitamin D can build up to toxic levels. At those extremes, vitamin D can raise blood calcium to levels that can cause grogginess, constipation , and even death.

Obesity : Research has found lower vitamin D levels in people with obesity , or a body mass index BMI of 30 or more. This link may be stem from the ways in which body fat affects vitamin D absorption. Some people with obesity may spend less time outdoors due to mobility issues.

Those who have undergone bariatric surgery may also have absorption problems. Conversely, people whose BMI of 25— The authors suggest that dietary factors are responsible for this difference. Skin type : People with darker skin need more sunlight exposure to produce vitamin D than those with lighter skin.

People with pale skin or a history of skin cancer may avoid sun exposure to protect their skin from damage. Age : The ability to convert vitamin D to calcitriol may decline with age due to decreased kidney function.

As a result, calcium absorption will fall. Kidney and liver health : People with liver disease and kidney disease tend to have lower vitamin D levels. Pregnancy : The need for vitamin D may increase during pregnancy, but experts remain unsure whether supplements are a good idea. The authors of a Cochrane review concluded that taking supplements during pregnancy may reduce the risk of preeclampsia , gestational diabetes, low birth weight, and severe bleeding after delivery.

However, it may also increase the risk of preterm birth, which is birth before 37 weeks. The authors called for further research. Breastfeeding infants : Human milk is low in vitamin D, which means that breastfeeding infants are at risk of a deficiency. The Centers for Disease Control and Prevention CDC recommend giving a vitamin D supplement to all breastfeeding infants from the first few days of life until they consume 1 l or more of formula milk each day.

Supplementation becomes unnecessary at this point because formula milk contains added vitamin D. In , experts published a report on data from — They looked at how vitamin D deficiencies affect specific populations in the U. The findings suggested that African American adults have the highest risk of a deficiency, followed by Hispanic people. A vitamin D deficiency may produce no symptoms, or symptoms may take several years to appear.

However, it may increase the risk of long term health problems. Osteoporosis : The bones become thin or brittle. The first sign may be a bone breaking easily as a result of minor trauma. It often affects older people. Osteomalacia : This can affect children. The bones become soft, resulting in bone deformities, short stature , dental problems, fragile bones, and pain when walking. Researchers are looking into whether other symptoms or conditions, such as depression , bone pain , and weakness, may result from low vitamin D levels.

Can low vitamin D levels lead to hair loss? Find out here. If a blood test shows that a person has or is at risk of a vitamin D deficiency, the doctor is likely to advise them to increase their intake. The ODS recommend the following intake each day:. Furthermore, vitamin D may enhance the anti-inflammatory effects of glucocorticoids.

This benefit makes it potentially useful as a supportive therapy for people with steroid resistant asthma. A review suggests that pregnant women who are deficient in vitamin D may have a greater risk of developing preeclampsia and giving birth preterm. Doctors also associate poor vitamin D status with gestational diabetes and bacterial vaginosis in pregnant women.

It is also important to note that in a study , researchers associated high vitamin D levels during pregnancy with an increased risk of food allergy in the child during the first 2 years of life.

Absorbing sunlight is essential for the skin to produce vitamin D. Covering the skin with clothing can inhibit vitamin D production also.

Geographical location: People who live in northern latitudes or areas of high pollution, work night shifts, or are homebound should aim to consume vitamin D from food sources whenever possible. Breastfeeding: Infants who exclusively breastfeed need a vitamin D supplement, especially if they have dark skin or have minimal sun exposure.

The American Academy of Pediatrics recommend that all breastfed infants receive international units IU per day of oral vitamin D. Supplement drops for babies are available online. Although people can take vitamin D supplements, it is best to obtain any vitamins or minerals through natural sources wherever possible. Read more on vitamin D deficiency. If Vitamin D deficiency continues for long periods, it may result in complications , such as:.

Getting sufficient sunlight is the best way to help the body produce enough vitamin D. Plentiful food sources of vitamin D include:. Here, learn how to get more vitamin D from the sun. People can measure vitamin D intake in micrograms mcg or international units IU. One microgram of vitamin D is equal to 40 IU. The recommended daily intakes of vitamin D are as follows:. Sensible sun exposure on bare skin for 5—10 minutes, 2—3 times per week, allows most people to produce sufficient vitamin D.

However, vitamin D breaks down quite quickly, meaning that stores can run low, especially in winter. The upper limit that healthcare professionals recommend for vitamin D is 4, IU per day for an adult. Excessive consumption of vitamin D can lead to over calcification of bones and the hardening of blood vessels, kidney, lung, and heart tissues.