Vitamin Information Center

Low serum vitamin D levels in older men are associated with a higher risk of cardiovascular mortality, noncancer mortality, and noncancer, noncardiovascular mortality, according to research presented here at the American Society for Bone and Mineral Research (ASBMR) 30th Annual Meeting.

Although low 25-hydroxy vitamin D (25-OH vitamin D) levels have previously been associated with an increased risk of fractures and some diseases in older men, few studies of all-cause and cause-specific mortality have previously been conducted in elderly males, said Peggy Cawthon, California Pacific Medical Center Research Institute, San Francisco, California, who presented results from the prospective study here on September 12.

“There’s been a lot of interest in vitamin D levels and various health conditions in older adults, and some recent observational studies have suggested there is an association between higher vitamin D and protection for mortality, so the more vitamin D you have, the less likely you are to die,” Cawthon explained.

To test the hypothesis that low serum levels of vitamin D are associated with an increased risk of mortality in older men, the researchers looked at 5,995 men aged 65 years and up at 6 clinics in the United States. All subjects were participating in the Osteoporosis Fractures in Men study. An analysis sample of 1,608 men was randomly selected, and the subjects were followed for 6.1 years.

Proportional hazards models were used to test associations between low vitamin D levels and overall mortality, noncancer mortality, and cancer mortality as well as cardiovascular death. Adjustments were made for factors such as age, clinical centre, and season of the blood draw.

The study found that men with vitamin D deficiency (≤15 ng/mL) had a 2.2-fold increased risk of death due to causes besides cancer, with no significantly increased mortality for those with levels of 15 to 30 ng/mL (P = .008).

The researchers also found, however, that there was no significant association between 25-OH vitamin D deficiency and death due to all types of cancer combined (relative hazard = 0.6; confidence interval, 0.2-1.4), with results for vitamin D deficiency similar to results in the lowest quartile of 25-OH vitamin D levels (≤20 ng/mL) compared to those in men in the highest quartile (≥30 ng/mL) (P = .12).

“We saw the opposite of what we expected,” Cawthon noted. “There’s not any other information in the literature that would suggest that association, and we’re not really sure why that is.”

Potential harmful effects of higher vitamin D levels should be investigated further in larger studies with better power, the investigators concluded. “We’d like to look at this in [the setting of] a randomised, controlled trial,” Cawthon said.

Increased intake of calcium and vitamin D can help prevent or slow bone loss in men, according to a pair of studies conducted by researchers from Deakin University in Melbourne, Australia.

An estimated 75 million women and men in the United States, Europe and Japan suffer from osteoporosis, a disease in which bones become thin and brittle.

Prior research has demonstrated that both calcium and vitamin D are important for the bone health of women, who are four times more likely to develop osteoporosis than men. In a 2006 study published in the journal Bone, scientists also found that older men who drank fortified milk daily experienced a 1.8 percent increase in the bone mineral density of their hip bones and a 1.5 percent increase in the density of their wrist bones.

The fortified milk contained 500 milligrams of calcium and 400 IU of vitamin D3, as well as other vitamins and minerals. The researchers noted that because the participants were given fortified milk instead of individual vitamin supplements, it was not possible to determine whether the bone density increase came from the calcium, the vitamin D, both, or some combination of those nutrients with others found in the milk.

The researchers also noted that while calcium intake was higher in participants who drank fortified milk than in control participants, this difference was not statistically significant.

In a more recent study, published in the American Journal of Clinical Nutrition, researchers followed up with 109 of the original study participants 18 months after that study’s conclusion. During that time, the participants had not been provided with fortified milk, but the bone-density improvements from the first study were still apparent.

The researchers suggested that supplementation of milk with calcium and vitamin D3, as is done in Canada, could lead to long-term bone health benefits for older men.

An abundance of vitamin C in the diet may help lower a person’s risk of developing type 2 diabetes, new research suggests.

In a study of middle-aged and older men and women, those with the highest blood levels of vitamin C were significantly less likely to develop diabetes over 12 years than those with the lowest levels, researchers found.

Fruits and vegetables are the main source of vitamin C in Western diets, and blood levels of vitamin C are good markers of fruit and vegetable intake, Dr. Nita G. Forouhi, at the Institute of Metabolic Science at Addenbrooke’s Hospital, Cambridge, England, and colleagues note.

The current findings “re-endorse the public health message of the beneficial effect of increasing total fruit and vegetable intake,” the investigators wrote in Archives of Internal Medicine.

Forouhi’s team followed 21,831 healthy men and women who were 40 to 75 years old for the development of type 2 diabetes. At study entry, all participants provided detailed health and lifestyle information, as well as blood samples, which investigators used to determine vitamin C levels.

Over the course of the study, 423 men and 312 women developed type 2 diabetes, an overall rate of 3.2 percent.

According to the investigators, the likelihood of developing diabetes was 62 percent lower in men and women with the highest circulating vitamin C levels, relative to men and women with the lowest vitamin C levels.

Factoring out other characteristics associated with diabetes risk, such as older age, gender, family history, alcohol intake, physical activity, smoking status and body weight did not significantly alter these associations.

These data offer “persuasive evidence of a beneficial effect of vitamin C and fruit and vegetable intake on diabetes risk,” Forouhi and colleagues conclude.