In The News: July 2018

A recently published study examined the possible association between higher levels of plasma 25-hydroxyvitamin D and lower risk of type II diabetes, in view of past reports suggesting this link.*

The researchers focused on a cohort of 903 adults with vitamin D levels at what they described as the high end of normal, above 32 ng/mL, because there had previously been no adequate data in that range.

The subjects were free of diabetes or prediabetes from 1997 to 1999 during testing at the National Institutes of Health Lipid Research Centers clinic. Over subsequent years, through 2009, subjects were tested for fasting plasma glucose and oral glucose tolerance, as well as vitamin D levels.

Ultimately, there were 47 diabetes cases and 337 cases of prediabetes. Compared to levels of vitamin D below 30 ng/mL, subjects with higher vitamin D blood levels had a lower risk of developing type II diabetes.

Those with the highest vitamin D levels, above 50 ng/mL, had the lowest risk. This is the blood level (over 50 ng/mL) typically seen in people who supplement with 3,000 IU to 8,000 IU a day of vitamin D3 with a meal containing some fat.

Editor’s Note: This study tested for an association between vitamin D and lower diabetes risk, but did not establish a causal relationship. The researchers encourage further study to determine if high doses of vitamin D might prevent type II diabetes or the transition of prediabetes to diabetes.

A promising avenue for preventing or treating esophageal cancer is suggested by a recent study that shows zinc can impede progression of the disease.*

While a link between zinc deficiency and esophageal cancer had already been noted in previous studies, the mechanism underlying the mineral’s apparent anticancer effects was previously unknown.

The study, led by Zui Pan of the College of Nursing and Health Innovation at the University of Texas at Arlington, found that zinc inhibits the growth and proliferation of esophageal cancer cells by blocking a particular calcium channel that is known to contribute to cancer growth.

Zinc was not found to have the same effect on healthy cell lines.

Compared to other types of cancer, the prognosis for esophageal cancer is generally poor, with a five-year survival rate for only 20% of cases. Pan and fellow researchers are optimistic that zinc supplementation could be a viable approach for prevention and/or treatment of the disease.

Editor’s Note: Study leader Zui Pan remarks: “Our study, for the first time to our knowledge, reveals that zinc impedes overactive calcium signals in cancer cells, which is absent in normal cells, and thus zinc selectively inhibits cancer cell growth.”

Those being treated for esophageal cancer should ensure they are obtaining 25-50 mg of zinc each day.

An article appearing in Breast Cancer Research and Treatment reported an association between greater consumption of soy foods and cruciferous vegetables and a lower risk of experiencing side effects from breast-cancer therapy.*

The study included 173 non-Hispanic Caucasian and 192 Chinese-American breast-cancer survivors. Dietary intake data was obtained from responses to mailed questionnaires. Telephone interviews obtained information concerning treatment-related symptoms, including joint problems, fatigue, hair loss or thinning, memory problems and menopausal symptoms.

Consuming 24 grams per day or more of soy was associated with a 49% lower risk of experiencing menopausal symptoms and a 57% lower risk of fatigue compared to no soy.

In comparison with subjects whose intake of cruciferous vegetables was less than 33 grams per day, consuming 70.8 grams or more was associated with half the risk of menopausal symptoms. The associations were significant for Caucasian breast-cancer survivors.

Editor’s Note: It was suggested that isoflavones occurring in soy and glucosinolates in cruciferous vegetables could be responsible for the reduction in symptoms observed in the study.

A trial reported in the Journal of the American College of Nutrition found improvement in glucose metabolism as well as a decrease in oxidative stress and advanced glycation end products (AGEs) among individuals with diabetic nephropathy (kidney damage caused by diabetes) who received coenzyme Q10 (CoQ10) compared to those who received a placebo.*

The trial included 50 participants with diabetic nephropathy who, for 12 weeks, received either 100 mg of CoQ10 per day or a placebo. Blood samples collected before and after the treatment period were analyzed for insulin, hemoglobin A1c, plasma malondialdehyde (MDA, a marker of lipid peroxidation) and AGEs.

At the end of the trial, participants who received CoQ10 had lower serum insulin, less insulin resistance, less oxidative stress, and lower levels of AGEs compared to levels measured before treatment, while the placebo group failed to experience improvements in these factors.

Editor’s Note: AGEs are proteins or fats that become glycated during exposure to glucose, which can damage tissue.