Having high vitamin D levels is important for all ages. However, vitamin D levels generally decline in old age while at the same time risk of diseases linked to low vitamin D levels increases. Thus, maintaining high vitamin D levels at this age is very important. The primary reasons that vitamin D levels decrease with age are that older people spend less time in the sun, and when they do, their efficiency at making vitamin D from solar ultraviolet-B (UVB) light is much lower than for younger people. Vitamin D is made from a type of cholesterol in the skin, and the amount decreases with increasing age.

The primary diseases associated with disability and death in old age are cancer, cardiovascular disease, dementia, falls and fractures, and infectious diseases. Low vitamin D has been found to increase the risk for all of these diseases. A moderate amount of calcium supplementation, perhaps 500 mg/day, along with 250 mg/day magnesium, also helps reduce the risk of cancer and falls and fractures.

The optimal vitamin D level is at least 30 ng/ml, with indications that 40-50 ng/ml is better. To reach these levels can take 1000-4000 IU/d depending on a number of factors including weight, genetics, whether statins are being used, amount of time spent in the sun, etc. For those who don’t want to take vitamin D supplements daily, larger amounts such as 10,000 and 50,000 IU capsules are available which can be taken less frequently such as once weekly.

I have estimated the benefit of doubling vitamin D level from the world average of 20 ng/ml to 40 ng/ml, finding that mortality rate should decrease by about 15%, thereby adding two years to life expectancy. The younger one is when vitamin D level is raised to 40 ng/ml, the greater will be the benefit since the effects of vitamin D deficiency accumulate and not all can be erased.

The simplest thing to do is take a reasonable amount of vitamin D. However, to make sure that vitamin D levels are in the optimal range, it is worthwhile to have the vitamin D level measured. Any physician can order such a test. For those who would like to have a measurement made outside of the office, two non-profit organizations offer a mail-in kit that can be ordered. It comes from ZRT Laboratory. It includes a lance for drawing small amounts of blood and a card for placing two blood spots. The measurement is as accurate as those using wet blood as I determined by having blood drawn on the same day to have my vitamin D measured by three laboratories. The two organizations that offer it areGrassrootsHealth.net and VitaminDCouncil.org.

There is mounting evidence that vitamin D plays an important role in reducing risk of developing cardiovascular disease as well as the diseases that often precede it such as diabetes mellitus and chronic kidney disease. The category cardiovascular disease includes coronary heart disease (heart attack), stroke, peripheral arterial disease, and congestive heart failure.

Several observational studies found that those with low vitamin D levels had increased risk of developing cardiovascular disease in general and stroke, congestive heart failure, coronary heart disease, and peripheral arterial disease in particular. The evidence is largely from observational studies that enroll people in a study and take blood samples at that time, then follow them for several years, noting any adverse health outcomes.Risk reduces rapidly for increases of vitamin D levels above the lowest values, then more slowly as vitamin D levels reach about 40 ng/ml.

To reach this level takes 1000-4000 IU/day vitamin D3depending on a number of factors.

Vitamin D also reduces risk of several diseases that often lead to cardiovascular disease such as diabetes mellitus and, likely,chronic kidney disease.

It has also been proposed that vitamin D deficiency is a risk factor forerectile dysfunction since about half of the cases of erectile dysfunction have vascular causes.

The mechanisms whereby vitamin D reduces risk of these diseases include reducing inflammation and the risk of arterial stiffness.Vitamin D also helps maintain insulin sensitivity for proper control of glucose. There issome evidence that vitamin D reduces levels of triglycerides, LDL-cholesterol, and hemoglobin A1C (HbA1C). It is not clear whether vitamin D affects blood pressure.

Vitamin D has at least two ways of reducing the risk of infectious diseases. One is through strengthening both the innate and adaptive immune systems, the other is through reducing inflammatory responses to infection. The “innate immune system”responds to threats in a non-specific manner. The “adaptive immune system” can recognize and deal with specific threats it has faced before.

Recall the old days when people with tuberculosis went to sunny locations to cure their illness? The primary benefit was production of vitamin D from solar ultraviolet-B (UVB) exposure, followed by strengthening the innate immune system.

There is also good evidence that vitamin D protects against other bacteria. The earliest evidence for other bacteria was for bacteria associated with dental cavities. A vitamin D supplementation study in 1928 noted that for children taking vitamin D, there were fewer cavities and the cavity-causing bacteria were dead. Several studies from the 1930s to 1950s reported that young people living in sunnier locations in the United States had fewer dental cavities than those living in the less sunny locations. A recent review reported that many studies found reduced number of dental cavities for those with vitamin D supplementation.

There is also good evidence that vitamin D reduces risk of sepsis (blood infection). This infection often sends people to the hospital, or may be acquired in the hospital, perhaps after an operation. Thus, those planning to enter the hospital should consider making sure their vitamin D level is above 30-40 ng/ml.

Pneumonia is yet another bacterial infection that vitamin D can help prevent. For example, during the 1918-19 epidemic influenza in the United States, the primary cause of death after contracting influenza was pneumonia. However, those living in the sunnier communities had lower death rates after developing influenza than those living in the less sunny communities. Vitamin D helped in two ways: first by reducing the aggressive immune response that among other things ruptured some of the lining of the lungs, thereby permitting the ever present bacteria to invade, and second, by helping the innate immune system to fight the bacteria that lead to pneumonia.

There is also good evidence that vitamin D reduces the risk of viral infections. Influenza is more common in winter for two reasons: cold temperatures and low solar UVB doses and vitamin D production. A randomized controlled trial on Japanese school children found that those taking 1100 IU/d vitamin D3 had about one-third the rate of type A influenza as those taking 200 IU/d. Type A influenza is the most common type of influenza, such as the A/H1N1 influenza during the 1918-19 pandemic influenza and the recent “swine flu” epidemic. This reduction is similar to the effectiveness of influenza vaccination.

Both observational and randomized controlled trials have found that vitamin D reduces risk of acute respiratory infections.

There is also mounting evidence that vitamin D is beneficial for those with HIV/AIDS through strengthening the innate immune system.

So, what should one do regarding vitamin D to reduce the risk of bacterial and viral infections? Based on several studies, one should aim for vitamin D blood levels above 30 ng/ml or for better protection above 40 ng/ml. To achieve these levels takes anywhere from 1000 to 4000 IU/d vitamin D3, depending on amount of UVB exposure and weight.

Adequate vitamin D levels are very important during pregnancy and lactation. In addition to the classical role of vitamin D in calcium and phosphate absorption and metabolism, vitamin D during pregnancy protects against infection, helps ensure proper fetal development, and reduces the risk of adverse pregnancy outcomes. How vitamin D protects against infection is discussed in another blog. Infection during pregnancy has been linked to adverse effects on fetal development, so is to be avoided if possible.

Vitamin D helps with fetal development not only through calcium and phosphate effects but also through effects on gene expression. Vitamin D affects the expression of hundreds of genes, turning some on, turning others off. Since fetal development is controlled to a large extent by genes, this is a very important role for vitamin D.

A number of adverse pregnancy outcomes have been linked to low vitamin D levels. One study found that the risk of primary Cesarean section delivery increased as vitamin D levels decreased. One role of vitamin D is to strengthen muscles, which may help explain why vitamin D reduces risk of primary Cesarean section delivery.

Several studies have reported increased risk of gestational diabetes for those with low vitamin D levels. Vitamin D also reduces risk of both type 1 and type 2 diabetes mellitus.

Lower vitamin D levels are also associated with increased risk of pre-eclampsia.

Other studies have found links between vitamin D deficiency and both preterm delivery and small birth weight. These effects are more common among black-Americans, who have lower vitamin D levels than white Americans primarily due to having darker skin. Black-Americans are also more likely to have infants with rickets.

Another frequent development during pregnancy is periodontal disease. Those who develop periodontal disease during pregnancy often have adverse pregnancy outcomes. There is mounting evidence that vitamin D reduces the risk of periodontal disease. Thus, periodontal disease during pregnancy can be considered a warning sign of vitamin D deficiency.

The benefit of high vitamin D levels during lactation is that the nursing infant gets its vitamin D directly from the mother rather than having to take supplements.

Most of the findings just discussed are from observational studies. Health policy makers prefer randomized controlled trials to observational studies. One such trial was reported in 2011. The pregnant women were given as much as 4000 IU/d vitamin D3. The researchers found that it took 4000 IU/d to increase vitamin D levels to above 40 ng/ml, which was high enough to raise the active form of vitamin D to the optimal level. The active form of vitamin D activates gene expression and protects against infection. There were no adverse effects such as extra calcium in the blood or urine. They also found that those taking 4000 IU/d had significantly reduced risk of primary Cesarean section delivery and pre-eclampsia. They had too few women enrolled to find significant results for other pregnancy outcomes.

There is a large body of evidence that vitamin D reduces the risk of many types of cancerand improves survival after cancer diagnosis. Solar ultraviolet-B (UVB) light is the primary source of vitamin D for most people. The idea that UVB and vitamin D could reduce the risk of cancer was proposed in 1980 by the brothers Cedric and Frank Garland after seeing the map of colon cancer mortality rates in the United States and recognizing that the lowest rates were in the Southwest, which is the sunniest part of the country while the highest rates were in the Northeast, which is the least sunny part of the country. This geographical statistical correlation approach has been used to link increased solar UVB doses to reduced risk of about 15 types of cancer: bladder, breast, colon, endometrial, esophageal, gallbladder, kidney, ovarian, pancreatic, prostate, rectal, stomach, vulvar cancer, Hodgkin’s and non-Hodgkin’s lymphoma.

Since these studies were based on solar UVB, additional studies are required to show that production of vitamin D provides the link between UVB light and cancer risk reduction. Observational studies, in which vitamin D levels for those who develop cancer are compared to those who do not, have provided strong evidence for vitamin D reducing the risk of breast, colon, pancreatic, and rectal cancer. Observational studies for breast cancer show that risk is highest for levels below 15 ng/ml and lowest above 30-40 ng/ml. For comparison, African-Americans have an average of 16 ng/ml while white-Americans have an average of 26 ng/ml.

There is also increasing evidence that higher vitamin D levels at time of cancer diagnosis are associated with better survival rates. The cancers for which this has been reported include breast, colon, lung, prostate, rectal cancer, lymphoma, and Hodgkin’s lymphoma. For colon and rectal cancer, those with higher vitamin D levels had twice the survival rate as those with low vitamin D levels.

So, what can the individual do to reduce the risk of cancer with sunlight and vitamin D? The most efficient way to increase vitamin D level is through taking vitamin D3 and calcium supplements. In the absence of testing, taking 1000-4000 IU/day vitamin D3 plus about 500 mg/day calcium and 250 mg/day magnesium is recommended. Since different people reach different vitamin D levels for the same vitamin D intake, measuring vitamin D levels before and after starting to take vitamin D supplements can be used to adjust the intake. Tests can be ordered through one’s physician or through two websites. GrassRootsHealth.net and VitaminDCouncil.orgoffer test kits from ZRT Laboratory that include a lance for pricking the finger and a piece of paper for two blood spots. The cost is about $70. The test is very accurate as I determined by comparing test results with those from two national testing companies. Both organizations also have large amounts of information on vitamin D.

Solar UVB is the primary source of vitamin D for most people, so exposing as much of the body as possible when the sun is high in the sky for an amount of time less than it takes to have any signs of burning (pinkness) daily is worthwhile. However, in the northern parts of the United States, it is not possible to make any vitamin D from sunlight during the four-to-five darkest months of the year. The fears about skin cancer and melanoma are largely overblown, so the sun should not be feared.

Additional information about the health benefits of vitamin D can be found at vitamindwiki.com and pubmed.gov.