Low Vitamin D: A Global Concern

Recent studies suggest that vitamin D is much more important in fighting off disease than previously thought. Being deficient in this vitamin puts one at risk of diseases such as cancer, osteoporosis, and multiple sclerosis. Chances are that if you live in a northerly geographic region you do not get enough vitamin D. Persons who live a rather sedentary lifestyle and do not get outside for at least a 15-minute daily walk in the sun are in the same position. Latinos, African-Americans and others with dark skin tend to have much lower levels of vitamin D, as do people who are overweight or obese. All around the world millions of persons suffer from vitamin D deficiency. This phenomenon is so common that it affects persons on every continent, of all ethnic groups, and across all ages. Some surveys suggest that perhaps half of the world’s population has inadequate blood levels of vitamin D. Sadly, physicians, even in industrialized countries, are seeing the resurgence of rickets, the bone-weakening disease that had been largely eradicated through vitamin D fortification.

As with most research findings, there is plenty of debate. Indeed, as opposed to what many people think, there are few certainties in science; its nature is to be open to criticism, discussion, and revision. The Institute of Medicine (IOM) released a report in November 2010 which recommends a daily vitamin D intake of 600 IU per day, for people ages 1 to 70, and 800 IU, for people over age 70—the report referred to persons living in the U.S. and Canada. The report also recognized the safety of vitamin D by increasing the upper limit from 2,000 to 4,000 IU per day, and acknowledged that even at 4,000 IU per day, there was no good evidence of harm.

Some in the scientific community believe the new guidelines are too conservative about the intake, and that they do not give due consideration to the latest findings about vitamin D and health. They contend that the new guidelines are not enough to prevent chronic disease, and they are not sufficient to help those who have problems with their bones. This is an important debate, and in order to understand it better it is necessary to know the origins of vitamin D and how it functions in the human body.

Vitamin D Sources and Function

Our body makes vitamin D and it is also a nutrient we eat. The body produces vitamin D from cholesterol, which itself is triggered by sun lighting on the skin. Yet many persons do not make enough vitamin D from the sun, persons with darker skin, those who are overweight, and persons who use products that block sunlight being among them. Correctly applied sunscreen reduces our ability to absorb vitamin D by more than 90 percent.

To be sure, not all sunlight is of the same quality and intensity: The sun’s ultraviolet B (UVB) rays—the so-called “tanning” rays, and the rays that trigger the skin to produce vitamin D—are stronger near the equator and weaker at higher latitudes. Indeed, persons who live in places prone to considerable cloudiness and rain can suffer from vitamin D deficiency. The other way we get vitamin D is to eat food that contains a lot of it. However, few foods are naturally rich in vitamin D, so the biggest dietary sources of vitamin D are fortified foods and vitamins supplements.

Vitamin D helps the body absorb and retains calcium and phosphorus, which are critical elements for building bone. Laboratory studies show that vitamin D can reduce cancer cell growth, can increase muscle strength, and can help control infections. There may yet be other functions for vitamin D, and scientists continue to explore the many other uses for this important substance.

New Vitamin D Research: Beyond Building Bones

Vitamin D research has proved to be of considerable fecundity. Although there have been many reports issued over the years, there are only a few that offer enough evidence to constitute a clear medical breakthrough. Here we provide the more promising areas of vitamin D research, highlighting the complex role of vitamin D in disease prevention—and the many unanswered questions that remain.

Vitamin D and Bone and Muscle Strength

A number of random trials have shown that high doses of vitamin D supplements help reduce bone fractures. A summary of the evidence comes from a combined analysis of 12 fracture prevention trials that included more than 40,000 elderly people, most of them women. Researchers found that high intakes of vitamin D supplements—of about 800 IU per day—reduced hip and non-spine fractures by over 20 percent, while lower intakes (400 IU or less) failed to offer any fracture prevention benefit.

It has been shown that vitamin D may also help increase muscle strength, which can help prevent elderly persons from falling, a common problem that leads to increased rates of disability and death among them. A combined meta-analysis found that taking 700 to 1,000 IU of vitamin D per day lowered the risk of falls by 19 percent; the combined studies also show that taking 200 to 600 IU per day offered no such protection. Based on this data, the International Osteoporosis Foundation recommends that adults over age 60 maintain vitamin D blood levels of 30ng/ml. This means that most people will need vitamin D supplements of at least 800 to 1,000 IU per day, and possibly higher, to reach these levels.

Vitamin D and Heart Disease

The heart, as a skeletal muscle, is a receptor of vitamin D. A number of studies have found that lack of vitamin D is linked to heart disease. The Health Professional Follow-Up Study observed the vitamin D blood levels in nearly 50,000 men who were healthy. They followed the same group for 10 years and found that men who were low in vitamin D were twice as likely to have a heart attack as men who had adequate levels of vitamin D. Other studies have linked low vitamin D levels to an increased of heart failure, sudden cardiac death, stroke, overall cardiovascular disease, and cardiovascular death. There is some evidence that vitamin D plays a vital role in controlling blood pressure and preventing artery damage. This goes some ways in explaining the findings above. However, more research is needed before a sounder conclusion can be made.

Vitamin D and Cancer

Nearly 30 years ago, researchers discovered an interesting correlation between colon cancer deaths and geographic location. They found that people who lived at higher latitudes, such as in the northern U.S. or Canada, had higher rates of death from colon cancer than people who lived closer to the equator. The sun’s UVB rays are weaker at higher latitudes, and in turn, people’s vitamin D levels in these high latitude locales tend to be lower. Researchers formed the hypothesis that vitamin D deficiency can lead to an increased risk for getting colon cancer

Some time has passed, but dozens of studies suggest a relationship does exist between low vitamin D levels and increased risks of colon and other cancers. The evidence is strongest for colorectal cancer, with observational studies have found that persons with lower vitamin D levels are at higher risk of getting such diseases. Vitamin D levels may also predict cancer survival, but there is as yet little evidence to support this. However, it is not yet certain that taking vitamin D supplements necessarily lowers the risk of contracting cancer. This latter idea will be tested in the VITAL trial. The VITAL trial will look specifically at whether vitamin D supplements lower cancer risk. However, it is likely to be years before the trial produces any results. Additionally, the VITAL trial could fail to detect a real benefit of vitamin D. There are several reasons for this. First, if people in the placebo group decide to take their own vitamin D supplements, the differences between the placebo group and the supplement group could be minimized. Second, the study may not follow participants for a long enough time to show a cancer prevention benefit; or study participants may be starting supplements too late in life to lower their cancer risk.

In any case, given the evidence now on hand, 16 scientists have circulated a “call for action” on vitamin D and cancer prevention. Given the high rates of vitamin D inadequacy in North America, the strong evidence for reduction of osteoporosis and fractures, the potential cancer-fighting benefits of vitamin D, and the low risk of vitamin D supplementation, these scientists recommend vitamin D supplementation of 2,000 IU per day. The Canadian Cancer Society has also recommended that Canadian adults consider taking vitamin D supplements of 1,000 IU per day during the fall and winter. They also recommend that people who are at high risk of having low vitamin D levels because of old age, dark skin, or geographic location take vitamin D supplements year round.

What Dose of Vitamin D is Most Effective?

The most beneficial dose of vitamin D supplementation needed to reduce fall risk has not been established. Douglas P. Kiel, M.D., associate professor of medicine at Harvard Medical School in Boston and the director of medical research at the Boston-based Hebrew Senior Life center, studied 125 nursing home residents with an average age of 89. There were no baseline differences across the participants, except for their age. Participants either received a placebo, 200 international units, 400 international units, 600 international units or 800 international units of vitamin D. Dr. Kiel and his colleagues found those getting 800 international units of vitamin D had a 71-percent reduction in risk of falls compared with those getting lower doses or placebo. And compared to the participants receiving 800 international units of vitamin D, the other four groups had a three- to four-fold increase in the hazard ratio for a fall.

Dr. Kiel concludes to achieve maximum benefit in the nursing home setting, vitamin D doses of 800 international units or higher may be needed.

Clinical Trial of Vitamin D

“Vitamin D supplementation at a dose sufficient to elevate serum levels above 30 ng/mL does not appear to have any symptom- or structure-modifying benefits for knee osteoarthritis,” said Timothy E. McAlindon, MD, MPH, Tufts Medical Center, Boston, Massachusetts, speaking here on November 8 at a press briefing sponsored by the ACR and, later, in an oral presentation.

Participants who markedly increased their ingestion of vitamin D supplement reduced their based pain scores by about 2.14 points compared with a reduction of 1.20 points among patients who were taking placebo as assessed by the Western Ontario and McMaster Universities Osteoarthritis Index. That difference, however, did not achieve statistical significance (P >.05).

Similarly, differences in the Chair Stand Test, tibia and femur volume and thickness, and minimum joint space width did not achieve differences that were statistically significant, said Dr. McAlindon.

In the study, 146 participants were randomised to either vitamin D 2,000 mg/day or placebo for 2 years. The goal of supplementation was to increase vitamin D levels above 30 ng/mL, achieved through an average increase of 15 ng/mL in the group taking vitamin D, while the placebo patients increased vitamin D levels by 1.8 ng/mL (P <.0001). The participants in this study were mainly white women with an average age of just over 62 years. Their average body mass index was 30.7. At baseline, their average vitamin D level was 22.3 ng/mL. The researchers performed physical-function tests and x-rays on each participant at the beginning of the study and again at 12 months. They also computed the knee-cartilage volume and thickness, and the bone-marrow lesion volume from the magnetic resonance imaging studies taken at the baseline and at 12 months to determine whether any changes had occurred. Dr. McAlindon suggested that other ongoing clinical trials with vitamin D in arthritis patients might give further direction as to how scientists might pursue further studies with the agent. He noted that, when tested in rigourous clinical trials, antioxidants, vitamin C, vitamin D, beta-carotene, and other supplements have failed to produce the positive results seen in anecdotal and observational reports. He added that he was surprised by the results. "When you spend … years on a project you hope for a positive outcome," Dr. McAlindon commented. News Source: DG News - Ed Susman

Vitamin D Help on Disease Prevention

Can vitamin D help with the symptoms of multiple sclerosis (MS)? Will vitamin D supplementation delay the progression of MS in someone who has MS?

Patients with multiple sclerosis are often vitamin D deficient. Since vitamin D deficiency causes muscle weakness, correcting their vitamin D deficiency significantly improves overall muscle function. If you have multiple sclerosis, there is no reason not to have your vitamin D status checked, be treated for your vitamin D deficiency, and prevent the recurrence of vitamin D deficiency.

In milk to moderate cases of osteopenia (the prelude to osteoporosis), would taking adequate vitamin D and calcium be enough to prevent osteoporosis, thus eliminating need for osteoporosis medications?

May men and women who present with milk or moderate osteopenia are vitamin D deficient and calcium deficient. It is recommended that the calcium be taken in two or three divided doses, rather than all at once, because it will be more bioavailable. The vitamin D can be taken any time.

Does vitamin D have any association with scoliosis in adolescent girls? Can vitamin D supplementation help correct spinal curvature?

It’s not aware of any association between scoliosis and vitamin D deficiency in adolescent girls. However, many adolescent girls are vitamin D deficient, and to maximize their bone health, they should be receiving an adequate amount of vitamin D and calcium. But vitamin D supplementation will not correct spinal curvature. Unfortunately, this is a permanent deformity. But if the vitamin D deficiency is exacerbating the spinal curvature, correcting vitamin D deficiency may help prevent further curvature from occurring. Keep in mind that vitamin D will also improve muscle strength; a study out of Lebanon showed that 2,000 IU a day to girls ten to seventeen years old did just that. Another recent study, which examined the influence of vitamin D levels on bone mass, bone turnover, and muscle strength in 301 healthy Chinese adolescent girls, also confirmed the importance of adequate vitamin D in reaching peak bone mass and muscle strength.

Would the recommendation be the same for Down’s syndrome and intellectual disability patients?

It is recommended that children over one year and adults receive at least 1,400 to 2,000 IU of vitamin D a day if they are not getting adequate exposure to sunlight. This also applies to patients with Down’s syndrome and with intellectual disabilities.

I have primary hyperparathyroidism and my calcium is elevated and I am vitamin D deficient. My doctor says taking vitamin D will increase my calcium level and therefore I should avoid vitamin D. True?

This is not true. Two studies have proved that, if anything, your parathyroid hormone and calcium levels will be improved by correcting the vitamin D deficiency.

I have sarcoidosis and my doctor says I should not take vitamin D because it could cause my calcium to elevate above normal. True?

It is true that excessive exposure to sunlight or taking too much vitamin D can cause the macrophages in the sarcoid tissue to make too much activated vitamin D. however, patients should not remain vitamin D deficient, because that can cause muscle weakness and symptoms of osteomalacia (aches and pains in bones and muscles).

I have kidney disease and am on dialysis. My doctor said that since my kidneys cannot make activated vitamin D from 25-vitamin D, there is no need for me to take vitamin D to maintain my blood levels of 25-vitamin D above 30 nanograms per milliliter. Is this correct?

No. the National Kidney Foundation recommend that all patients with kidney failure – even patients with no kidneys – should maintain 25-vitamin D levels of 30 to 100 nanograms per milliliter.

What about people who have a vitamin D receptor (VDR) defect and need more vitamin D?

Patients who have a VDR defect can sometimes benefit by increasing their vitamin D intake. It depends upon the severity of the alteration in the VDR gene. Patients with the VDR gene mutation known as vitamin D-resistant rickets or vitamin D-dependent rickets type II will sometimes benefit from being treated not only with vitamin D but also with the active form of vitamin D.

I take medications that make me extra sensitive to the sun. What should I do?

If you cannot expose yourself to the sun for any amount of time, then supplementation is key. Ami to take 2,000 IU of vitamin D a day year-round. This can be in addition to any multivitamins containing vitamin D, vitamin D-fortified foods and beverages, and vitamin D-rich fish you consume.

A lot of women are being given gabapentin for hot flashes instead of estrogen. Can it lower 25-vitamin D levels?

It is not known that whether gabapentin (brand name Neurontin or Gabarone) used for treating hot flashes will lower 25-vitamin D levels. However, we do know that many drugs will enhance the destruction of vitamin D in the body. Thus, at a minimum taking at least 2,000 IU of vitamin D a day and having your blood level of 25-vitamin D monitored.

The current recommendation of 400IU of vitamins D per day may not be enough to prevent vitamin D deficiency during the winter months. USANA’S supplement has 2000 IU of vitamin D per tablet.