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Vitamin D needed for male fertility
The June, 2011 issue of the journal Human Reproduction reported the finding of Danish researchers of a role for vitamin D in sperm motility: the movement of spermatozoa that is necessary for fertilization.
Martin Blomberg Jensen of Copenhagen University Hospital and his associates evaluated motility in sperm samples from 300 Danish men. Blood samples were analyzed for 25-hydroxyvitamin D, parathyroid hormone and other factors.
Forty-four percent of the subjects were found to have insufficient vitamin D levels, which were inversely correlated with parathyroid hormone. Increasing vitamin D levels were associated with greater sperm motility as well increased progressive motility, which is the highest grade of sperm motility, applied to sperm that swim rapidly in a straight line.
In an in vitro experiment utilizing sperm samples donated by 40 men, vitamin D3 was demonstrated to increase intracellular calcium via vitamin D receptor-mediated calcium release, improve sperm motility, and induce the acrosome reaction, which is needed for fertilization of the ovum.
"Low semen quality may have numerous causes, but it often has a fetal origin similar to some male genital malformations and testicular cancer,” remarked coauthor Anders Juul of the University of Copenhagen. “However, this study indicates that factors in adult life may also play a role for semen quality. It is important to find all factors of importance, because semen quality in Danish men is at a low level and contributing to a very high incidence of fertility problems among Danish couples.”
“Our study is not sufficient and should not be used to change existing treatment practices,” noted Dr Blomberg Jensen. “However, it uncovers some of the functions of vitamin D and generates new hypotheses. This is an intriguing finding, because it suggests that vitamin D has an effect on sperm movement and function.”
Vitamin D deficiency in African Americans more prevalent among those with MS
An article published in the May 24, 2011 issue of Neurology® reports the finding of researchers at the University of California, San Francisco of a greater incidence of vitamin D deficiency in African Americans with multiple sclerosis (MS) compared to those who do not have the disease. The study is the largest to date to examine vitamin D status in this population.
"MS is not as common in African-Americans as it is in whites, although the disease tends to be more severe in African-Americans," commented lead researcher and American Academy of Neurology member Ari J. Green, MD. "We have known that vitamin D levels are associated with MS and that African-Americans are at increased risk for having low vitamin D levels, but little research has been done to look at vitamin D levels in African-Americans with MS."
Dr Green and his associates compared the 25-hydroxyvitamin D levels 339 African American men and women diagnosed with MS to 342 who were free of the disease. Ninety-four percent of all subjects were classified as having insufficient levels of vitamin D, defined as 25-hydroxyvitamin D levels of less than 30 nanograms per milliliter. While deficiency, defined as levels of less than 20 nanograms per milliliter, was uncovered in 71 percent of participants without MS, 77 percent of those with the disease were found to be vitamin D deficient. Multiple sclerosis patients also tended to live at higher latitudes and were exposed to a lower monthly ultraviolet index. There was no correlation observed between vitamin D levels and disease severity. Dr Green suggests that MS patients request a vitamin D blood test with their physician and discuss the need for vitamin D supplementation.
“These findings may provide a mechanism to help explain how genes and the environment interact to produce MS," he concluded.
Nutritional supplements reduce pre-eclampsia risk
An article appearing online on May 19, 2011 in the British Medical Journal reports the finding of Mexican and US researchers of a protective effect for a nutritional supplement combination against pre-eclampsia, a serious condition characterized by high blood pressure and other abnormalities that can occur during pregnancy. Research suggests that a deficiency of the amino acid L-arginine and/or other nutrients could play a role in the development of the condition.
The current study included pregnant Mexican women at high risk of pre-eclampsia. Beginning in their twentieth week of pregnancy through delivery, 228 women were given a food bar that contained L-arginine and the vitamins niacin, folate, and vitamins B6, B12, C and E; and 222 received bars that contained only vitamins. An additional 222 women received placebo bars. Blood pressure and arginine levels were assessed every three to four weeks.
While over 30 percent of the women in the placebo group developed pre-eclampsia, the condition developed in 22.5 percent of those who received bars fortified with vitamins only, and in just 12.7 percent of those who received L-arginine plus vitamins. Women in the latter group also experienced a significantly lower risk of premature delivery compared to those who did not receive arginine.
L-arginine’s protective effect against pre-eclampsia has been attributed to an ability to help maintain healthy blood flow via increased production of nitric oxide. While authors Felipe Vadillo-Ortega and his colleagues admit that it is unknown whether the benefits observed in the current study were due to L-arginine or the combination of the amino acid and antioxidant vitamins, they conclude that "This relatively simple and low cost intervention may have value in reducing the risk of pre-eclampsia and associated preterm birth."
Antioxidant defense impairment implicated in asthma
A presentation on May 16 at the American Thoracic Society’s 2011 International Conference revealed the finding of Emma Larkin, PhD and her associates at Vanderbilt University of a role for the body’s antioxidant defense system in the development of asthma.
“Oxidative stress, which is a relative increase of oxidants over antioxidants, is known to be important in many diseases, including asthma,” Dr Larkin explained. “It’s a battle between charged oxygen species that produce damage and our body’s ability to fight them off.”
The current study involved 453 participants in the Shanghai Women’s Health Asthma and Allergy Study. One hundred fifty women who developed asthma after enrolling were matched with 294 healthy control participants. Urinary F2-isoprostane, a measure of oxidative stress, and serum antioxidant enzymes platelet-activating factor acetylhydrolase (PAF-AH), superoxide dismutase and paraoxonase were measured upon enrollment. Dr Larkin and her colleagues found that high levels of the enzyme PAF-AH (which prevents the formation of platelet-aggregating factor), was associated with a lower risk of asthma.
“In our study, we took a multi-step approach to understanding the development of asthma, by looking at the enzymatic and the non-enzymatic ways that the body manages oxidative stress in the development of adult-onset asthma,” she remarked. “Specifically, we focused on the enzymatic defense system that precedes the onset of asthma symptoms and diagnosis.”
“Because this study helps us understand what is occurring in the body prior to the development of symptomatic asthma, the results may point us to nutrients or classes of drugs that could be studied to prevent asthma in those who are high-risk,” she said. “There are a lot of data on the dietary intake of antioxidants and levels of antioxidants in the blood – the non-enzymatic defenses. By focusing on the enzymatic defenses, this study helps give us a clearer picture of the complete asthma development process.”
Ability of selenium supplementation to elevate glutathione varies
An article published in the latest issue of the journal Nutrition and Cancer reveals the finding of researchers from Penn State University of elevations in the level of glutathione in response to supplementation with the mineral selenium in Caucasians. Glutathione is a tripeptide antioxidant compound that has been associated with protection against reactive oxygen species. Previous research suggests that the protective effect of selenium against some cancers is the result of the reduction in oxidative stress caused by the mineral’s ability to enhance concentrations of glutathione and GCL, an enzyme involved in its synthesis.
For the current investigation, John P. Richie, Jr of Penn State Cancer Institute and his associates utilized data from 161 African American and 175 Caucasian men and women who participated in a study of residents of southeastern and mid-Westchester County, New York. The researchers observed a correlation between higher selenium levels and increased concentrations of glutathione as well as increased GCL activity. Higher levels of selenium were measured in Caucasian subjects compared to African Americans.
At the conclusion of a small trial of selenium supplementation previously conducted by the researchers, a 114 percent increase in plasma selenium concentrations was observed among Caucasian subjects, while only a 50 percent increase occurred in African Americans. Glutathione increased by 35 percent among the Caucasian participants, yet no increase was observed in the African American subjects.
“These results suggest that decreases in selenium status and its subsequent effects on glutathione and oxidative stress may be playing an important role in the mechanism by which Blacks are at greater risk for certain cancers, including prostate cancer,” the authors write. “These findings may translate into race-specific prevention strategies involving selenium-containing compounds, many of which are currently under development for use as chemopreventive agents.”
Insufficient vitamin D levels prevalent in obese adolescents
An article appearing in the May, 2011 issue of the Journal of Adolescent Health, reports the finding of researchers from Hasbro Children’s Hospital and Brown University Medical School of low vitamin D levels among obese adolescent boys and girls.
Pediatrician Zeev Harel, MD and his colleagues reviewed data from 68 obese adolescents with a mean age of 17 years. Serum sample analysis provided 25-hydroxyvitamin D levels and other factors.
Insufficient levels of vitamin D were found in 22 percent of the boys and 28 percent of the girls, and deficiency was revealed in 69 and 72 percent. Participants with insufficient vitamin D levels were subsequently treated with 800 international units (IU) vitamin D per day for three months, and those with deficiency received 50,000 IU vitamin D per week for 6 to 8 weeks. Blood levels of vitamin D after treatment determined whether the subjects received an additional course of treatment, followed by repeat serum 25-hydroxyvitamin D measurement.
"The prevalence of low vitamin D status among obese adolescents in this study is greater than previously reported for this age group,” Dr Harel remarked. “It is concerning to us that only 28 percent of the adolescents were able to reach normal vitamin D levels through one course of treatment of the recommended dose of vitamin D, while the other 72 percent failed to normalize their levels even with repeat treatments".
"Based on the findings from this study, we are calling for increased surveillance of obese adolescents whose vitamin D levels do not normalize after initial course of treatment,” he stated. “In addition, prospective studies are needed to evaluate whether normalizing vitamin D levels in obese adolescents will help lower the health risks associated with obesity."
Aspirin use associated with reduced risk of prostate cancer recurrence
On May 1, 2011 a presentation at the 93rd Annual Meeting of the American Radium Society revealed that prostate cancer patients who regularly used aspirin had a lower risk of their cancer recurring compared with men who did not use aspirin.
Mark Buyyounouski, MD, MS and colleagues evaluated data from 2,141 men with prostate cancer who were treated with radiation at Fox Chase Cancer Center between 1989 and 2006. A decade following the completion of their treatment, 31 percent of the 761 men who used aspirin during or after radiotherapy experienced biochemical failure as indicated by rising prostate specific antigen (PSA) levels, in comparison with 39 percent of the subjects who did not report aspirin use. Additionally, ten year survival improved by 2 percent in aspirin users.
"Hopefully, these clinical results will provide feedback to laboratory researchers to try to explain the underlying mechanism so that we can better study the clinical effects in targeted populations," stated Dr Buyyounouski, who is a radiation oncologist with Fox Chase Cancer Center. "It’s possible aspirin therapy is making the radiation more effective or preventing the cancer from spreading."
“It's a little premature to say that men need to start taking aspirin if they have a history of prostate cancer," he added.
“We know that prostate cancer has a long natural history and 15 years or more may be necessary to detect significant difference in survival," Dr. Buyyounouski noted. "Longer follow-up is needed, but these results warrant further study."
Reduced vitamin D levels associated with anemia in children
A presentation on May 1, 2011 at the annual meeting of the Pediatric Academic Societies held in Denver revealed the finding of pediatricians from Johns Hopkins Children's Center of an association between childhood anemia and decreased vitamin D levels. Anemia is diagnosed by measuring hemoglobin in the blood, which, when reduced, indicates an insufficient amount of oxygen-carrying red blood cells.
Johns Hopkins pediatric nephrologist Meredith Atkinson, MD, MHS and colleagues examined hemoglobin and 25-hydroxyvitamin D levels in blood samples obtained from 9,460 boys and girls between the ages of 2 and 18 who were enrolled in the in the National Health and Nutrition Examination Survey (NHANES) 2001-2006. Nine percent of African American children were found to be anemic compared with just 1 percent of Caucasian children. African American children also had, on average, much lower levels of vitamin D, with levels averaging 18.0 nanograms per milliliter compared to 27 ng/mL in Caucasian children.
Children with vitamin D levels of less than 20 ng/mL had a 50 percent higher risk of anemia than those whose levels were 20 ng/mL or more. The risk of anemia declined by 3 percent for each 1 ng/mL increase in vitamin D.
It has long been known that anemia is more prevalent among African American children, yet the reason for this disparity has yet to be defined. "The striking difference between black and white children in vitamin D levels and hemoglobin gives us an interesting clue that definitely calls for a further study," Dr Atkinson commented.