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D-ficient teens have stiff arteries
In an article scheduled for publication in The Journal of Clinical Endocrinology & Metabolism, researchers from the Medical College of Georgia in Augusta report that African-American teenagers who are deficient in vitamin D exhibit arterial stiffness, which is a risk factor for stroke and heart disease.
Yanbin Dong, MD, PhD and colleagues randomized 44 male and female African-American teens to receive 400 international units (IU) or 2,000 IU vitamin D3 per day for 16 weeks. Arterial stiffness was assessed using pulse wave velocity at the beginning and end of the treatment period. Plasma 25-hydroxyvitamin D levels were evaluated prior to treatment and at 4, 8 and 16 weeks.
Vitamin D levels significantly increased by 8 weeks among those who received 2,000 IU and exceeded sufficient levels of at least 75 nanomoles per liter by the end of the study. Although plasma vitamin D also increased in the control group, reaching an average of 59.8 nanomoles per liter 25-hydroxyvitamin D by the end of the study, this level is still below that which is considered sufficient. While arterial stiffness increased among those who received 400 IU vitamin D, it decreased significantly in participants who received 2,000 IU compared to baseline levels.
"While we think of the sun as providing humans with most of our body's requirement of vitamin D, 95 percent of the 44 black teenagers living in sunny Georgia who took part in this study were classified as vitamin D deficient," Dr Dong observed.
"Our study is the first clinical trial of vitamin D intervention to use 2,000 IU in black subjects and to include cardiovascular risk factors as outcomes in youth," she announced. "Our study indicates that the current recommendations for vitamin D intake in black teenagers may need to be revised upward."
DHEA protects against obesity and breast tumors in animal study
Writing in the August, 2010 issue of Oncology Reports, researchers at the University of Arkansas for Medical Sciences describe the results of a study of obese rats which found that supplementation with the hormone dehydroepiandrosterone (DHEA) resulted in reduced weight gain and protection from carcinogen-induced mammary tumors. Obesity has been linked with the risk of development of breast cancer, and DHEA, which declines with age, has been used as a supplement to counter weight gain and other age-associated conditions.
“In regards to weight reduction and breast cancer development, a dietary supplement intervention that can help to reduce body weight and consequently reduce the risk of breast cancer development would be beneficial,” the authors write. “Since DHEA is marketed as a supplement with purported health benefits, including weight loss, we used DHEA as a dietary supplement to investigate its effects on both body weight and its effects on breast cancer.”
The researchers fed a control diet or a diet that contained 6 grams DHEA per kilogram chow to 43 six week old rats that were bred to develop obesity. At seven weeks of age, all of the animals received the carcinogen DMBA, which induces the formation of mammary tumors. The rats were checked for tumors weekly beginning one month after receiving DMBA until the study’s conclusion.
One hundred fifty-five days after the animals were given the carcinogen, those that received DHEA had significantly less weight gain than animals that did not receive the hormone. While 55 percent of the animals on the control diet had mammary tumors, none were detected in those that received DHEA.
“We have demonstrated that DHEA treatment can reduce body weight gain and protects against DMBA induced mammary tumor development in the obese Zucker rat model,” the authors conclude. “The mechanism for this protection remains to be defined and will be the subject of future investigation.
Children with celiac disease need vitamins
Research conducted at the University of Alberta has revealed that children who have celiac disease, an autoimmune disease that renders susceptible individuals intolerant to gluten in grains, are often deficient in such important nutrients as vitamin K and D which help protect the bones from developing osteoporosis later in life. The genetic disorder necessitates that its sufferers follow a life-long gluten-free diet in order to avoid small intestine mucosal damage.
University of Alberta professor of agricultural food and nutritional science Diana Mager and her associates studied 43 children aged 3 to 18 with celiac disease. They found that the children were consuming, on average, less than 50 percent of the recommended dietary intake of vitamin K as well as experiencing reduced levels of vitamin D. The subjects also had low bone density or osteopenia, which is likely a result of poor vitamin and mineral intake and absorption.
“Increasing awareness that these children are at equal risk of low bone mass will be useful to promote increased screening and for the development of clinical guidelines for monitoring bone mass in pediatric celiac disease and for determining the need for vitamin and mineral supplementation,” the authors write. “This is particularly necessary in pediatric celiac disease because of the risk of ongoing metabolic bone disease, independent of symptoms, particularly around the time of adolescence when bone accrual peaks.”
"Children with celiac disease are at risk for poor bone health, but by adding vitamins K and D to their diets, it can help reduce the risk of fractures and osteoporosis," Dr Mager stated.
Dr Mager also recommends that children afflicted with celiac disease increase their physical activity to help build bone strength, noting that outdoor exercise can increase vitamin D levels, although the Canadian latitude limits sunlight exposure.
Gene affected by calorie restriction protects against Alzheimer’s disease
Research described in the July 23, 2010 issue of the journal Cell reveals a protective effect for SIRT1, a gene that mediates some of the effects of calorie restriction, against the production of destructive amyloid beta peptides and the brain plaques formed by these peptides in an animal model of Alzheimer’s disease. Amyloid plaques in the brain are a hallmark of Alzheimer’s disease, and are believed to be a cause of the neurologic damage and dysfunction observed in these patients.
The SIRT1 gene, which is the mammalian version of SIRT2, produces proteins known as sirtuins, and has been demonstrated to be involved in a number of cell activities. Leonard Guarente and his colleagues at Massachusetts Institute of Technology tested the effects of SIRT1 overexpression in mice bred to develop Alzheimer’s plaques and symptoms. They found that SIRT1 directly activates the transcription of the gene that encodes a form of alpha-secretase, an enzyme that breaks apart amyloid precursor proteins into harmless protein fragments. Mice that overexpressed SIRT1 had reduced amyloid peptides, while those that had the gene inactivated experienced increased levels.
“Our findings clearly indicate that SIRT1 can suppress Alzheimer’s disease in a mouse model for this disease,” Dr Guarente and his associates write. “SIRT1 has been implicated in protection against metabolic syndrome and diabetes, and sirtuin activators may offer promising new treatments for these increasingly common disorders.”
“Our findings indicate that another important disease of aging, Alzheimer's disease, is also mitigated by genetic activation of SIRT1,” they conclude. “It may therefore be critically important to develop sirtuin activators tailored to cross the blood brain barrier to treat neurodegenerative diseases.”
Green tea supplementation reduces weight and BMI
Research described this year in the Journal of the American College of Nutrition revealed that supplementing with green tea extract or drinking green tea resulted in a decrease in weight and body mass index in obese men and women with metabolic syndrome, a precursor of diabetes.
Oklahoma State University researchers assigned 35 men and women to receive one of the following 8 week regimens: 4 cups green tea per day, 2 capsules green tea extract and 4 cups water per day, or 4 cups water per day. The green tea capsules contained a total of 460 milligrams of the active compound epiogallocatechin-3-gallate (EGCG) per day and the tea beverage provided a total of 440 milligrams EGCG. Weight, lipids, biomarkers of oxidative stress and other factors were measured upon enrollment, and at 4 and 8 weeks.
At the end of the treatment period, body mass index and weight were reduced in those who received green tea compared to the control subjects. Participants who received green tea extract lost an average of 1.9 kilograms and those who consumed the green tea beverage experienced a decrease of 2.5 kilograms in pairwise comparisons with age and gender-matched controls. Participants who received the tea beverage also experienced reductions in LDL-cholesterol, the ratio of LDL to high-density lipoprotein, and lipid peroxidation.
“To our knowledge, the study reported here is the first to show that green tea beverage and extract supplementation for 8 weeks leads to a significant weight loss in obese subjects with metabolic syndrome compared with age- and gender-matched controls,” the authors announce. “Because our test agents were commercially available green tea and green tea extracts, our study findings indicate the benefits of a feasible and cost-effective cardioprotective dietary intervention for the general public,” they conclude.
Over half the world deficient in vitamin D
In an article published in the July 2010 issue of Endocrine Today, distinguished professor emeritus of biochemistry and biomedical sciences and vitamin D expert Anthony Norman stated that half the people in North America and Western Europe do not have adequate levels of vitamin D.
"Elsewhere, it is worse, given that two-thirds of the people are vitamin D-insufficient or deficient” he added. “It is clear that merely eating vitamin D-rich foods is not adequate to solve the problem for most adults."
Dr Norman has studied vitamin D for nearly half a century, and his laboratory was responsible for the discovery of the vitamin’s conversion to a steroid hormone in the body. His research also identified the vitamin D receptor, which is present in over 37 organs.
While the Canadian government recently increased its vitamin D recommended intake, in the United States the recommended daily intake of vitamin D is 200 international units (IU) for men and women under the age of 50, 400 IU for those 51 to 70 years old, and 600 IU for older individuals. "There is a wide consensus among scientists that the relative daily intake of vitamin D should be increased to 2,000 to 4,000 IU for most adults," Dr Norman noted.
"The benefits of more research on the topic justifies why this field of research deserves additional governmental funding," he remarked. "Already, several studies have reported substantial reductions in incidence of breast cancer, colon cancer and type 1 diabetes in association with adequate intake of vitamin D, the positive effect generally occurring within five years of initiation of adequate vitamin D intake."
"There is now irrevocable evidence that receptors in the immune, pancreas, heart-cardiovascular, muscle and brain systems in the body generate biological responses to the steroid hormone form of vitamin D," he concluded.
Diets that contain more vitamin E associated with less dementia
Researchers from Erasmus Medical Center in Rotterdam, Netherlands and Harvard University report in the July, 2010 issue of the Archives of Neurology the finding of an association between a greater intake of vitamin E from one’s diet and a lower risk of developing dementia.
Elizabeth E. Devore, ScD, and her associates evaluated data from 5395 participants aged 55 and older in the Rotterdam study, which was designed to investigate determinants of disease in older populations. Dietary questionnaires completed between 1990 and 1993 were analyzed for levels of beta-carotene, flavonoids and vitamins C and E. Over a 9.6 year average follow-up period, dementia developed in 465 subjects, including 365 cases of Alzheimer’s disease.
A significant association was observed between vitamin E intake and a reduced risk of developing dementia. Participants in the top one-third of vitamin E intake had a 25 percent lower adjusted risk of developing dementia over follow-up compared with those whose intake was among the lowest third. A similar protective effect was observed for the vitamin against Alzheimer’s disease. Primary food sources of vitamin E included margarine, sunflower oil, butter, cooking fat, soybean oil and mayonnaise. No significant effects were found for vitamin C, beta-carotene and flavonoids in this study.
"The brain is a site of high metabolic activity, which makes it vulnerable to oxidative damage, and slow accumulation of such damage over a lifetime may contribute to the development of dementia," the authors write. "In particular, when beta-amyloid (a hallmark of pathologic Alzheimer's disease) accumulates in the brain, an inflammatory response is likely evoked that produces nitric oxide radicals and downstream neurodegenerative effects. Vitamin E is a powerful fat-soluble antioxidant that may help to inhibit the pathogenesis of dementia."
Soy could reduce menopausal weight gain
A presentation at the Annual Meeting of the Society for the Study of Ingestive Behavior (SSIB), held July 13-17, 2010 in Pittsburgh, revealed an anti-obesity effect for soy phytoestrogens in a rat model of menopause. The decline of estrogen that occurs during menopause is believed to be responsible, in part, for the increased weight gain that can occur during and following this transition, including a gain in dangerous abdominal fat. In laboratory animals, administration of estradiol reduces this effect, however, estrogen replacement therapy is contraindicated for some women. Because soy phytoestrogens such as isoflavone are structurally similar to estrogen and have been purported to have estrogenic benefits, Michelle Murphy and her colleagues at the Monell Chemical Senses Center in Philadelphia evaluated the effects of soy on 16 female rats that had their ovaries surgically removed to mimic menopause and 15 rats that received sham surgeries. Half of the animals in each group were given diets rich in soy isoflavones while the remainder received phytoestrogen-free control diets.
In ovariectomized as well as sham-operated rats, animals that received soy had lower body weights compared to the control groups at the end of the study. Measurement of food intake, activity, oxygen consumption and carbon dioxide production for four days revealed greater heat production and activity in animals that received soy. “These findings suggest that soy isoflavones inhibit obesity-related symptoms of menopause by increasing physical activity and energy expenditure” the authors concluded.
"These results have implications for the development of alternative natural treatments for obesity in post-menopausal women," Dr Murphy commented. "In this world of an ever-increasing obesity epidemic, finding natural dietary solutions and treatments to combat obesity are of the utmost importance both to worldwide health and economy."
High tocopherol and tocotrienol levels linked to lower Alzheimer’s disease risk
Researchers at the Karolinska Institutet in Stockholm and the University of Perugia report the finding of a protective benefit for high vitamin E levels against Alzheimer’s disease.
The study, published in the in the July, 2010 issue of the Journal of Alzheimer’s Disease, included 232 participants in the Kungsholmen Project, a longitudinal study on aging and dementia based in Stockholm. The subjects were 80 or more years of age and free of dementia at the beginning of the study. Plasma levels of vitamin E components alpha, beta, delta and gamma tocopherol and tocotrienols were measured upon enrollment, and participants were followed for 6 years, after which 57 cases of Alzheimer’s disease were diagnosed.
Francesca Mangialesche and her associates found that participants whose plasma levels of tocopherols, tocotrienols, or total vitamin E were in the highest one-third of participants had a 45 to 54 percent lower risk of developing Alzheimer’s disease compared to those whose levels were among the lowest third. “Vitamin E is a family of eight natural components, but most studies related to Alzheimer’s disease investigate only one of these components, alpha-tocopherol", stated Dr Mangialasche. "We hypothesized that all the vitamin E family members could be important in protecting against AD. If confirmed, this result has implications for both individuals and society, as 70 percent of all dementia cases in the general population occurs in people over 75 years of age, and the study suggests a protective effect of vitamin E against AD in individuals aged 80+."
"Elderly people as a group are large consumers of vitamin E supplements, which usually contain only alpha-tocopherol, and this often at high doses," she noted. "Our findings need to be confirmed by other studies, but they open up for the possibility that the balanced presence of different vitamin E forms can have an important neuroprotective effect."
Women who use fish oil supplements experience a lower risk of breast cancer
A report published online on July 8, 2010 in the American Association for Cancer Research journal Cancer Epidemiology, Biomarkers & Prevention reveals a protective effect for fish oil supplements against cancer of the breast. Fish oil contains high amounts of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), omega-3 fatty acids that are frequently reduced in modern diets.
The current study included 35,016 postmenopausal women who were members of the VITamins And Lifestyle (VITAL) Cohort. Questionnaires completed from 2000 to 2002 provided information concerning the frequency and duration of use of non-vitamin, non-mineral supplements including fish oil and supplements that target menopausal symptoms, such as black cohosh.
At the 6 year follow-up, 880 cases of breast cancer were diagnosed among the participants. Women who had reported regular use of fish oil supplements had a 32 percent lower risk of invasive ductal breast cancer, the most common form of the disease, compared to those who did not report being current users. Other supplements did not appear to effect risk.
The study is the first to reveal an association between supplementing with fish oil and a decrease in breast cancer risk. "It may be that the amount of omega-3 fatty acids in fish oil supplements is higher than most people would typically get from their diet," remarked Emily White, PhD of the Fred Hutchinson Cancer Research Center in Seattle, who led the research. "Without confirming studies specifically addressing this, we should not draw any conclusions about a causal relationship."
Future research in the form of a clinical trial, also known by the name of VITAL, plans to enroll 20,000 older men and women to test the effects of omega-3 fatty acids and fish oil on the risk of heart disease, stroke and cancer.
DHEA improves conception rates in women undergoing treatment for infertility
An article published in AYALA, the journal of the Israeli Fertility Association, reveals a benefit for the hormone dehydroepiandrosterone (DHEA) in improving the rate of conception and live births in women treated for infertility. DHEA is a steroid produced in the adrenal glands and the brain, and is available in the United States as an over-the-counter supplement.
Professor Adrian Shulman of Tel Aviv University's Sackler Faculty of Medicine and the Meir Medical Center and associates conducted a clinical trial which evaluated the effects of DHEA in 20 women receiving pharmaceutical treatment for poor ovulation. The women were divided to receive 75 milligrams DHEA 40 days before beginning treatment with the drug and continued for up to 5 months.
Women who received DHEA were three times likelier to conceive compared with those being treated with fertility drugs alone. "In the DHEA group, there was a 23% live birth rate as opposed to a 4% rate in the control group," reported Dr Shulman, who is director of the IVF of the Obstetric and Gynecology Department at Meir Medical Center. "More than that, of the pregnancies in the DHEA group, all but one ended in healthy deliveries."
The trial is the first controlled study of the effects of DHEA in infertility. Dr Shulman hopes that future studies will reveal a mechanism for the hormone. "We need to look into what the drug actually does to make the body more fertile,” he remarked. “It could be affecting components such as the quality of the eggs or the follicles."
"We recommend that women try this DHEA treatment, in conjunction with fertility treatments, for four to five months," Dr Shulman stated. He added that women should consult their medical practitioner before initiating therapy.
Vitamin D insufficiency associated with metabolic syndrome
A study reported at The Endocrine Society's 92nd Annual Meeting in San Diego revealed an increased risk of metabolic syndrome among older adults with insufficient vitamin D levels.
Metabolic syndrome is a cluster of risk factors which include low HDL cholesterol, high triglycerides, hypertension, abdominal obesity, and disordered blood glucose. The condition is estimated to affect 25 percent of adults and is a precursor of diabetes and cardiovascular disease.
The current investigation was a substudy of the Longitudinal Aging Study Amsterdam (LASA), an ongoing cohort study of a sample of older individuals in the Netherlands. Researchers at VU University Medical Center in Amsterdam analyzed data from 630 men and 659 women aged 65 and older of whom 36.9 percent had metabolic syndrome determined during 1995-1996. They found that 48 percent of the subjects had insufficient levels of vitamin D, which were associated with an increased risk of having three or more metabolic syndrome criteria. Those with serum 25-hydroxyvitamin D levels below 50 nanomoles per liter had a 32 percent higher risk of metabolic syndrome than those with higher levels, with low HDL and greater waist circumference being the components mainly associated with insufficient vitamin D. No significant differences between men and women were observed.
The researchers plan to evaluate data from a 2009 follow-up to determine the number of participants who developed diabetes. "Because the metabolic syndrome increases the risk of diabetes and cardiovascular disease, an adequate vitamin D level in the body might be important in the prevention of these diseases," co-author Marelise Eekhoff, MD, PhD stated. "It is important to investigate the exact role of vitamin D in diabetes to find new and maybe easy ways to prevent it and cardiovascular disease.”