February 28, 2007
Prenatal formulas inadequate to prevent vitamin D deficiency
A study reported in the February, 2007 Journal of Nutrition concluded that the majority of African-American women and almost half of Caucasian women have deficient levels of vitamin D, as do most of their infants, despite the use of prenatal supplements. Deficient levels of vitamin D can result in rickets and other childhood health conditions.
For the current study, assistant professor of epidemiology at the University of Pittsburgh Graduate School of Public Health Lisa Bodnar, PhD, MPH, and colleagues investigated the vitamin D levels of 200 African American and 200 Caucasian women participating in the Magee-Women's Research Institute's Pregnancy Exposures and Preeclampsia Prevention Study which enrolled over 2,200 women between 1997 and 2001. Blood samples were tested for vitamin D before the twenty-second week of pregnancy and prior to delivery, and the newborn infants' cord blood was also tested.
"In our study, more than 80 percent of African-American women and nearly half of white women tested at delivery had levels of vitamin D that were too low, even though more than 90 percent of them used prenatal vitamins during pregnancy," Dr Bodnar stated. "The numbers also were striking for their newborns – 92.4 percent of African-American babies and 66.1 percent of white infants were found to have insufficient vitamin D at birth."
In an accompanying editorial, American Cancer Society senior epidemiologist Marjorie L. McCullough, ScD observed, "This study is among the largest to examine these questions in this at-risk population. By the end of pregnancy, 90 percent of all women were taking prenatal vitamins and yet deficiency was still common."
"Our study shows that current vitamin D dietary intake recommendations are not enough to meet the demands of pregnancy," Dr. Bodnar concluded. "Improving vitamin D status has tremendous capacity to benefit public health."
February 26, 2007
Soy may help prevent weight gain, diabetes
An article published online on February 26, 2007 in the Journal of the Science of Food and Agriculture reported the finding of researchers in Korea that black soy bean protein given to rats on a fatty diet helped prevent weight gain and lowered cholesterol.
Shin Joung Rho of Hanyang University in Seoul and colleagues gave 32 male rats a diet containing 36 percent fat and 1 percent cholesterol. The diet provided 2, 6 or 10 percent of its calories as a black soy peptide. A control group of rats received the diet with 20 percent of its calories as casein. The animals consumed the diets for 28 days.
At the conclusion of the investigation, rats who consumed soy had less weight gain compared to those that received the casein-enriched diet, as well as lower total cholesterol and serum LDL to HDL ratio. After two weeks, rats in the group whose diets provided 10 percent of their calories from soy had gained half the amount of weight as animals in the control group. Rats in this group experienced a reduction in total cholesterol of 25 percent and a 60 percent decline in LDL.
David Bender, who is sub-dean at the Royal Free and University College Medical School, London, believes that soy protein may be affecting liver and adipose tissue fat metabolism, reducing the synthesis of new fatty acids and cholesterol, which may explain the traditional use of black soy in Asia as a diabetes treatment. "The key problem in type II diabetes is impairment of insulin action, mainly as a result of excess abdominal adipose tissue - so loss of weight often improves glycemic control," Dr Bender observed.
The authors concluded "that black soy protein can be a potent nutraceutical component for anti-obesity and hypolipidaemic benefits."
February 23, 2007
Higher antioxidant levels correlate with lower periodontitis prevalence
A report published in the March, 2006 issue of the Journal of Nutrition revealed the finding of researchers at the University of Birmingham in England and Boston University that higher serum antioxidant levels are associated with a reduction in the risk of periodontitis. Periodontitis is an inflammatory condition of the tissue surrounding the teeth which has been linked with an increase in stroke, type-2 diabetes, and heart disease.
The current study examined data from 11,480 participants in the Third National Health and Nutrition Examination Survey (NHANES III), for whom periodontal measurements and serum levels of alpha-carotene, beta-carotene, selenium, lutein, uric acid, beta-cryptoxanthin, vitamins A, C and E, bilirubin, and total antioxidant levels were available.
Fourteen percent of the subjects were found to have mild periodontitis and 5 percent had severe disease. Higher vitamin C, bilirubin, and total antioxidant levels were associated with a lower incidence of periodontitis, particularly with severe disease. Individuals whose vitamin C levels were in the top 20 percent of participants had a 39 percent lower risk of periodontitis than that of participants in the lowest fifth. For subjects who had never smoked, the risk experienced by the top fifth was half that of the lowest fifth.
Vitamin C's protective benefit against periodontitis may arise from its involvement in collagen synthesis which helps maintain the structural integrity of connective tissue. Additionally it acts as a free radical scavenger and may help reduce inflammation.
The authors remark that longitudinal studies would be necessary to determine whether periodontal therapy reduces the inflammatory burden in the peripheral vasculature and to confirm the role of antioxidant levels as risk factors for periodontal disease. They write, "If confirmed, intervention studies involving antioxidant approaches would be indicated to determine the potential for reducing the risk of periodontitis."
February 21, 2007
Plant derived fatty acids help protect bone
In addition to the known protective effect of fish-derived omega-3 polyunsaturated fatty acids (PUFAs) on bone, a study conducted at Penn State University found that omega-3 fatty acids derived from plant sources have a protective benefit as well.
As part of a larger study investigating the effects of omega-3 fatty acids on cardiovascular health, Penn State associate professor of nutrition Rebecca Corwin and colleagues assigned twenty men and three postmenopausal women to three consecutive diets over a twenty-four week period. For the first six weeks, the participants consumed one of two diets high in polyunsaturated fatty acids or an average American diet. After a three week break during which they followed their regular eating patterns, the group resumed the study with one of the diets they had not previously followed. This was followed by another three week period of normal eating, after which the participants were assigned to the remaining diet for the final six weeks of the study.
The high in polyunsaturated fatty acid diets were either high in the omega-3 fatty acid alpha-linolenic acid (ALA) or the omega-6 fatty acid linoleic acid (LA). Walnuts supplied 50 percent of the fat in both diets, and flaxseed oil was used in the high alpha-linolenic acid diet. Blood tests for markers of bone formation and bone resorption were conducted before and after the dietary periods.
The researchers found that N-telopeptides, a biomarker for bone resorption, significantly decreased during the diet high in ALA and to a lesser extent during the LA diet compared with the average American diet. Bone-specific alkaline phosphatases which measure bone formation were not affected.
"If less bone is being resorbed and the same amount of bone is being created, then there is a positive balance for bone health," Dr Corwin concluded.
February 19, 2007
Watercress lowers DNA damage, cancer risk
The February 2007 issue of the American Journal of Clinical Nutrition published the discovery of researchers in Northern Ireland that consuming watercress is associated with a reduction in DNA damage, which in turn reduces the risk of cancer. Watercress is a member of the cruciferous family of vegetables that includes broccoli and cabbage, which have been associated with a lower risk of several cancers when included in the diet.
Thirty men and women, half of whom were smokers, were randomized to consume their usual diet or receive the addition of 85 grams raw watercress daily for eight weeks. After a seven week period in which no watercress was consumed, the subjects switched regimens for an another eight weeks. Fasting blood samples were collected at the beginning and end of each eight week phase of the trial and several measures of lymphocyte DNA damage assessed. Plasma lutein, retinol, alpha-tocopherol and beta-carotene levels were also measured.
Significant reductions in DNA damage occurred when the participants consumed watercress. These reductions were of a greater magnitude in smokers. Plasma lutein levels doubled following watercress supplementation, and beta-carotene concentrations rose by approximately one third, although the increase proved to be greater among nonsmokers.
Watercress may exert its protective effect on the genes due to its rich antioxidant content, in particular, lutein and beta-carotene. Analysis of watercress leaves detected several phenolic components such as rutin, as well as a number of glucosinolates, which may also contribute to its protective effect. The difference in beta-carotene levels between smokers and nonsmokers in this study could be due to a greater requirement of the vitamin by individuals who smoke. The authors conclude that their findings "provided important evidence that supports the hypothesis that consumption of watercress, a cruciferous vegetable, can reduce cancer risk in humans via a decrease in DNA damage."
February 16, 2007
Women who consume more seafood have children with better neurologic function
Contrary to the belief that a diet containing unrestricted amounts of seafood could harm the unborn children of expectant mothers due to seafood's high methylmercury levels, a study published in the February 17, 2007 issue of The Lancet found that pregnant women who consumed the most seafood had children with a higher verbal IQ than women whose intake was lower. Seafood is the best dietary source of omega-3 fatty acids, which are needed for optimum fetal brain development, however pregnant women in the United States are advised to limit seafood intake.
Joseph Hibbeln of the National Institutes of Health in Bethesda, Maryland and his colleagues analyzed data from the the Avon Longitudinal Study of Parents and Children (ALSPAC) for the current study. Mothers who participated in ALSPAC completed questionnaires concerning diet, social circumstances, education, and behavioral and developmental outcomes four times during their pregnancies and at specific time points thereafter. The children's IQ was measured at age 8.
It was found that women whose intake of seafood was less than 340 grams had an increased risk of giving birth to children whose verbal IQ was in the lowest 25 percent of the children in the study compared with women whose intake was greater. Children born to women who consumed low amounts of seafood also had a greater risk of suboptimal scores for prosocial behavior, fine motor, communication, and social development.
"We recorded no evidence to lend support to the warnings of the US advisory that pregnant women should limit their seafood consumption," the authors conclude. "In contrast, we noted that children of mothers who ate small amounts (<340 g per week) of seafood were more likely to have suboptimum neurodevelopmental outcomes than children of mothers who ate more seafood than the recommended amounts."
February 14, 2007
Many older individuals not meeting vitamin K requirement
The January, 2007 issue of the journal Current Opinion in Clinical Nutrition and Metabolic Care, published an article by Sarah Booth of Tufts University USDA Human Nutrition Research Center on Aging which reviewed studies concerning vitamin K status among the elderly. Dr Booth found that even though they appear to consume more of the vitamin than younger individuals, many are not receiving the recommended intake.
Vitamin K deficiency has been linked with chronic diseases involving abnormal calcification. "Research has shown poor vitamin K intake may be associated with conditions such as bone fractures, bone loss, hardening of the arteries, and osteoarthritis," Dr Booth observed.
While dietary intake of the vitamin is important, other factors may be involved its status. "One promising area of research is the interrelationship between estrogen and vitamin K, as studies indicate that low estrogen levels in menopause may change the way vitamin K is metabolized," Dr Booth noted. "More research is also needed to determine vitamin K status of elderly men, as well as to determine what populations, if any, might benefit from vitamin K supplements."
In a study published in the January, 2007 issue of Nutrition, Metabolism & Cardiovascular Diseases, Dr Booth and her colleagues evaluated the diets of over 40,000 men and determined that while vitamin K levels did not appear to be an independent marker of reduced cardiovascular disease risk, men with higher levels of the vitamin had improved dietary habits, were more likely to exercise or take dietary supplements, and were less likely to be smokers. The authors concluded that "...In large population groups, phylloquinone may provide a more robust assessment of overall cardiovascular risk status than assessing multiple individual diet and lifestyle habits."
"Evidence is emerging to support recommendations to increase intakes of vitamin K among the elderly to reduce bone loss and fracture risk," Dr Booth concluded.
February 12, 2007
Optimal levels of folate and vitamin B12 needed for maintaining cognitive function
In a report published in the January 2007 issue of the American Journal of Clinical Nutrition, researchers at Tufts University presented evidence that folic acid and vitamin B12 work together to protect cognitive function, and that high levels of folate do not necessarily mask the signs of a vitamin B12 deficiency as has been the concern for several decades.
Martha Savaria Morris, PhD and colleagues analyzed data from the National Health and Nutrition Examination Survey (NHANES) for the current study. "We found a strong relationship between high folate status and good cognitive function among people 60 and older who also had adequate levels of vitamin B12," Dr Morris reported.
"People with normal vitamin B12 status performed better if their serum folate was high," Dr Morris explained, "but for people with low vitamin B12 status, high serum folate was associated with poor performance on the cognitive test. For seniors, low vitamin B12 status and high serum folate was the worst combination. Specifically, anemia and cognitive impairment were observed nearly five times as often for people with this combination than among people with normal vitamin B12 and normal folate."
"When folate fortification was considered, opponents raised the possibility that because more folate might mask anemia, many cases of vitamin B12 deficiency would go undetected, causing people with the condition to suffer neuropsychiatric consequences," she observed. "But in our study, the people with low vitamin B12 who also had high serum folate were more likely to exhibit anemia and cognitive impairment than subjects with low vitamin B12 status and normal serum folate. So although having high serum folate had an impact on cognitive function in our study, it did not cure anemia, as opponents of food fortification have suggested."
She added, "We hope our findings both inform the continuing debate about folic acid fortification and influence future efforts to detect and treat low vitamin B12 status among seniors."
February 9, 2007
Vitamin D3 helps protect skin from infection
In a report published online on February 8, 2007 in advance of publication of the March, 2007 issue of the Journal of Clinical Investigation, researchers at the University of California, San Diego (UCSD) School of Medicine described their finding that fluctuations in vitamin D3 levels affect the skin's ability to heal.
In African Americans it has been observed that low levels of the active form of vitamin D3 that often occur in this population correlate with increased susceptibility to infection. The vitamin may also be involved in the immune response to tuberculosis.
Professor of medicine Richard L. Gallo, MD, PhD and colleagues found that genes controlled by the active form of vitamin D (1,25D3)play a role in how the innate immune system is controlled in the skin. They discovered that cathelicidin, an antimicrobial peptide produced by white blood cells in wounds when bacteria are sensed, is elevated when skin cells called keratinocytes surrounding wounds raise their production of vitamin D3, which increases the expression of genes that detect microbes.
"Our study shows that skin wounds need vitamin D3 to protect against infection and begin the normal repair process," Dr Gallo stated. "A deficiency in active D3 may compromise the body's innate immune system which works to resist infection, making a patient more vulnerable to microbes."
"Our finding – that multiple, diverse genes controlled by 1,25D3 are increased after injury to the skin – suggests that the availability of D3 is essential to the wound. These responses are a previously unrecognized part of the human injury response," he added.
Dr Gallo's team is beginning clinical trials at UCSD Medical Center to test whether oral and topical vitamin D3 will help improve the immune defenses of individuals with disorders in antimicrobial peptide production such as atopic dermatitis.
February 7, 2007
Benign prostatic hyperplasia may not be so "benign"
A report published in the February, 2007 issue of the Journal of Urology revealed that benign prostatic hyperplasia (BPH), a disease characterized by an enlarged prostate gland and urinary urgency and frequency, is actually a pair of disorders, and one of them can lead to serious complications.
Robert Getzenberg, PhD of Johns Hopkins university and colleagues found that men with more severe BPH have higher tissue levels of a protein made by the gene JM-27. The team also developed a blood test to measure the protein in men with severe symptoms. In these men, the increased pressure of an enlarged prostate can lead to functional changes in the bladder if untreated. By diagnosing this form of BPH earlier, the damage could be prevented.
In the current study, blood samples from 68 men with symptomatic or asymptomatic benign prostatic hyperplasia were tested for JM-27 protein levels. Seventeen men had prostate cancer. The researchers discovered a significant difference in the levels of the protein between the groups. Although tissue levels of JM-27 are elevated in men with more severe symptoms, blood levels of the marker are lower.
"Our experiments show that the expression of this marker is related to the presence of the severe form of BPH and not to the size of the prostate or to the presence or risk of prostate cancer," Dr Getzenberg commented. "What we're looking at is two diseases: BPH that produces more mild symptoms and is less likely to lead to bladder and other urinary tract damage, and BPH that is highly symptomatic with increased potential to do damage to the bladder."
"The next step is to figure out which drugs work best on which form of the disease as differentiated by JM-27," Dr Getzenberg stated.
February 5, 2007
Garlic to be tested for infection in cystic fibrosis patients
Researchers at The University of Nottingham in England are planning to conduct a pilot study to determine whether garlic will help eradicate chronic lung infection with the bacteria Pseudomonas aeruginosa in cystic fibrosis patients. Cystic fibrosis is an inherited disease characterized by an overproduction of mucus in the lungs, which can lead to chronic lung-damaging chest infections.
Garlic has been used to prevent gangrene, to treat colds, and is also believed by some to help combat cancer. The researchers plan to give garlic capsules or a placebo consisting of olive oil to cystic fibrosis patients for two months. Sputum samples will be evaluated for Pseudomonas before and after the treatment to assess its effectiveness.
Treatments for Pseudomonas in cystic fibrosis patients attempt to destroy the bacteria when the infection initially appears. Established infection is treated with antibiotic nebulisers which are time consuming and often do not prevent the necessity of hospitalization. The current study will determine whether oral garlic supplements disrupt the communication of the Pseudomonas bacteria, thereby helping to prevent infection. Project team leader Dr Alan Smyth of the University of Nottingham's School of Human Development explained, “The garlic components inhibit a bacterial communication system called quorum sensing (QS). This is responsible for the germ forming tenacious colonies in the lungs called 'biofilms'. The QS molecules also switch on bacterial weapons such as 'elastase', an enzyme which breaks down elastic tissue in the lung.
“The beauty of this approach is that we may be able to render the germ harmless without killing it. If we use a conventional antibiotic which kills the Pseudomonas, there will always be some survivors, some of which may develop antibiotic resistance. The trick is not to allow Pseudomonas to use natural selection as a weapon against us.”
February 2, 2007
Antioxidants improve reduced endothelial dysfunction in divers
The February 1, 2007 issue of The Journal of Physiology published the discovery of researchers at the University of Split School of Medicine in Croatia and the Norwegian University of Science and Technology that consuming vitamins C and E before a scuba dive reduces some of the alterations in vascular endothelial function that can occur with this activity. It was recently determined that cardiovascular changes occur after each dive, although most of the changes have not been considered serious.
In one experiment, a group of seven men performed an initial scuba dive preceded and followed by ultrasound examination of endothelial and heart functions. For the second dive, the men were given 2 grams of vitamin C and 400 international units vitamin E two hours in advance. The depth and time of the dives were similar to those performed by recreational divers. In a second, randomized experiment, divers were given the vitamins or a placebo before two successive dives, and were evaluated one half hour, 24 hours, 48 hours and 72 hours later.
A single dive was associated with mild cardiac function changes and significantly decreased endothelial function. In both experiments, arterial endothelial dysfunction was reduced with antioxidant treatment, although heart and pulmonary artery function were not affected. Cardiovascular changes after diving lingered for up to three days, suggesting longer lasting adverse effects than had previously been determined.
In previous research, the team had discovered that a four week course of vitamins C and E protected against post-dive changes in endothelial function. They remark that the current experiments found this benefit with only a single oral dose. “Our data support the hypothesis that oxidative mechanisms play a major role in the changes observed after a single air dive,” they write.
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