Zinc levels associated with bone mineral density in men
A study published in the September 2004 American Journal of Clinical Nutrition discovered a positive correlation between zinc intake as well as zinc plasma levels, and bone mineral density in men. Low intake and blood levels of zinc have been associated with reduced bone mass in women, but their significance in men has until now been unknown.
Three hundred ninety-six men over the age of forty-five who had taken part in the Rancho Bernardo Study of heart disease risk factors were included in the current study. Standard health questionnaires were completed, bone mineral densities were measured, and plasma zinc analyses were conducted upon enrollment. Two food frequency questionnaires with a one year interval between them were completed by the subjects, and analyzed for zinc intake. Participants returned four years after their initial visit for a second bone mineral density test.
The mean zinc intake of the group was 11.2 milligrams per day. Bone mineral density declined over the four year period in all but two areas measured. The researchers found that both dietary intake of zinc and plasma zinc concentrations were significantly reduced in men whose bone mineral density scores were diagnostic of osteoporosis of the spine or hip compared to men who did not have the disease. In men whose plasma zinc levels were in the lowest one-fourth of participants, bone mineral density values at the beginning of the study were lower in all sites but one compared to those whose zinc concentrations were in the top 25 percent.
To the authors' knowledge, this study is the first to correlate plasma zinc concentrations with bone mineral density in older men. They recommend further research to explore the role of zinc deficiency in the development of osteoporosis in this population.
Low glycemic index diets work in rodents
A report appearing in the August 28 2004 issue of The Lancet detailed experiments conducted by David Ludwig MD and colleagues of the Optimal Weight for Life obesity program at Children's Hospital in Boston which found that rats provided with a low-glycemic index diet experienced greater body fat loss and a reduction in cardiovascular disease and diabetes risk factors compared to rats who consumed a high-glycemic diet. The glycemic index of a food rates the rapidity with which it releases sugar into the bloodstream. The consumption of low as opposed to high glycemic index foods may be helpful when for weight loss and the treatment of diabetes.
In the first study, eleven rats were given a high-glycemic index diet, and ten rats received a low-glycemic index diet. After eighteen weeks, rats who received the high-glycemic index diets had a 71 percent greater amount of body fat, 8 percent lower amount of lean body mass, and a greater amount of fat in the trunk area (correlated with elevated cardiovascular disease risk) than the low-glycemic index group. Low-glycemic index fed rats also had reduced glucose, insulin and triglyceride levels.
In a second experiment, fourteen rats were fed high or low glycemic index diets for seven weeks, after which each group of rats received the diet that the other group received during the first part of the experiment. Rats changed from the low to high glycemic diet had greater elevations in glucose and insulin than those switched from the high to low-glycemic diet.
And in an experiment involving twenty mice fed high or low-glycemic index diets for nine weeks, the high-glycemic index diet was associated with a 93 percent increase in body fat compared with the low-glycemic index group.
Dr Ludwig commented, “What the study shows is that glycemic index is an independent factor that can have dramatic effects on the major chronic diseases plaguing developed nations – obesity, diabetes, and heart disease."
Citrus fruit compounds ripe for new discoveries
The 228th national meeting of the American Chemical Society held in Philadelphia this month was the site of a symposium held from August 24-25 which revealed some of the newly discovered health benefits of compounds found in citrus fruits.
Several new findings emerged for grapefruit, whose consumption has declined due to prescription drug interaction concerns. Texas A & M University researchers reported that three compounds in grapefruit have been identified which inhibit an enzyme known as CYP3A4 that metabolizes and regulates specific drugs. These enzyme-blockers, classified as furocoumarins, which are responsible for the interaction between grapefruit and certain medications, may be developed into a pharmaceutical agent that increases drug bioavailability, thereby lowering the amount of drug one needs to take. In other Texas A & M research, freeze dried grapefruit pulp was found to reduce early colon cancer lesions in animals.
Scientists at Scripps Clinic, San Diego have discovered that grapefruit may lower insulin levels, promoting weight loss. The finding explains the results of a trial conducted earlier this year in which 100 men and women who drank grapefruit juice or ate half a grapefruit with each meal lost weight. And at the University of Hawaii, researchers discovered that drinking three glasses of grapefruit juice per day lowered the activity of a liver enzyme that is believed to activate carcinogens in cigarette smoke.
A researcher at Kanazawa Medical University in Japan reported that a compound in tangerines known as nobiletin has a protective effect against colon cancer in an animal model, and the peel of the fruit provides cholesterol-lowering compounds, as documented by a USDA study.
Citrus and other fruits have been found to yield a significant number of phytochemicals which provide an array of health benefits, and undoubtedly future research will reveal more exciting uses for these widely available and affordable additions to our diets.
Acetyl-L-carnitine improves symptoms of antiretroviral neuropathy
The July 23 2004 issue of the journal AIDS published the findings of British researchers that the amino acid acetyl-L-carnitine improves the symptoms of distal symmetrical polyneuropathy (DSP), an antiretroviral toxic neuropathy that occurs in many HIV-positive individuals treated with drugs known as nucleoside analogue reverse transcriptase inhibitors (NRTI). In addition, acetyl-L-carnitine was found to stimulate peripheral nerve regeneration in individuals with the neuropathy.
Twenty-one HIV-positive patients with antiretroviral toxic neuropathy were given 1500 milligrams oral acetyl-L-carnitne twice per day for up to thirty-three months. Skin biopsies were conducted at the beginning of the trial and at six to twelve month intervals during the course of the study. Biopsies were also obtained from five HIV-negative controls.
The skin samples obtained from those with neuropathy revealed a near total absence of nerve fibers in the epidermis, the subepidermal plexus and the vicinity of the sweat glands, whereas a normal pattern of nerve distribution was observed in the specimens taken from the control group. After six months of acetyl-L-carnitine therapy, nerve fibers were observed to have increased in these areas. These improvements continued or stabilized after two years of treatment with acetyl-L-carnitine. Neuropathic pain improved in fifteen of the twenty-one patients, and twelve of these became asymptomatic after acetyl-L-carnitine treatment.
The authors noted that participants who discontinued using acetyl-L-carnitine experienced a worsening of their symptoms, however this was not documented in the study. They discussed possible mechanisms of action for the amino acid, including foremost a direct antioxidant effect, and observe that acetyl-L-carnitine promotes peripheral nerve regeneration and function independently of its mechanism in preventing toxicity from antiretroviral drugs. Because NRTI pharmaceuticals are currently used in combination therapy for HIV, aetyl-L-carnitine may be helpful in preventing patients from discontinuing their treatment regimens.
Ginkgo to be tested in early dementia
The Imperial College London in collaboration with the London School of Hygiene and Tropical Medicine, the Royal London Homeopathic Hospital and University College London is planning to study the effects of ginkgo biloba on early dementia. Ginkgo is believed to improve blood vessel dilation, thereby increasing blood flow to the brain. It also has anticoagulant and antioxidant benefits. The herb has been used for five thousand years in Chinese medicine, and could be an inexpensive treatment for conditions involving memory loss. Pharmaceutical therapies include cholinesterase inhibitors, which help prevent the breakdown of the neurotransmitter acetylcholine.
Two hundred fifty individuals over the age of 55 with memory loss (one of dementia's early symptoms) who are still dwelling in their communities will be recruited for the double-blind trial. Participants will receive 60 milligrams ginkgo extract or a placebo twice per day for six months, and can continue any memory loss medications they are currently using. Periodic evaluations of the subjects' cognitive function, memory, behavior and quality of life will be conducted over the course of the trial.
The study will be the first to treat community dwellers with memory loss. Previous studies testing ginkgo on hospitalized patients with more advanced conditions have had mixed results. Imperial College London psychiatrist Dr James Warner, who is directing the study, commented, "We believe gingko may prove more effective if prescribed in a community setting, where patients' symptoms are usually less severe. This trial will help us to find out whether with gingko it's a case of 'the sooner the better', for patients who may benefit from taking it."
Vitamin E helps protect against upper respiratory infections in older individuals
A study published in the August 18 2004 issue of the Journal of the American Medical Association ( http://jama.ama-assn.org/ ) has found vitamin E to be protective against upper, but not lower respiratory infections.
Four hundred fifty-one individuals aged 65 and older at 33 long-term care facilities completed a course of 200 international units vitamin E per day or a placebo from April 1998 to August 2001. In addition, all of the subjects received a daily capsule which provided 50 percent of the recommended daily allowance for essential vitamins and minerals. The incidence of upper respiratory infections, such as acute bronchitis and pneumonia, and lower respiratory tract infections, including cold, influenza, sore throat, middle ear infection and sinusitis, was documented over the course of the trial.
Fewer subjects who received vitamin E acquired one or more respiratory tract infections than those who did not receive the vitamin. While vitamin E was not found to be protective against lower respiratory infections, participants who received the vitamin experienced a 20 percent decreased risk of acquiring the common cold, which comprised 84 percent of the upper respiratory infections reported over the course of the study. In addition, those taking vitamin E had fewer colds per person. Lead author Simin Nikbin Meydani PhD of Tufts University, and colleagues concluded, “Common colds are frequent and associated with increased morbidity in this age group, and if confirmed, these findings suggest important implications for the well-being of the elderly. Future studies in elderly individuals should assess the effect of vitamin E supplementation on the common cold and incorporate microbiologic methods to allow for assessment of the impact of vitamin E on specific types of respiratory pathogens.“
Choose red wine over gin
A study published in the July 2004 issue of the journal Atherosclerosis concluded, not surprisingly, that drinking red wine is healthier than drinking gin. While the cardioprotective effects of consuming moderate amounts of alcohol has been demonstrated in several studies, researchers have faced the challenge of determining which factors involved in drinking alcohol are responsible for its benefits. The current trial is the first to compare the anti-inflammatory benefits of different drinks.
Researchers led by Emanuel Rubin, MD, of Thomas Jefferson Medical University in Philadelphia, compared the effects of drinking red wine or gin on the inflammatory biomarkers that are involved in atherosclerosis. Forty men received either two drinks per day of red wine or gin for twenty days, followed by a fifteen day period during which no alcohol was consumed. The participants' experimental regimens were then switched, so that each individual received the beverage that they did not receive during the first part of the study. Blood samples taken before and after each half of the trial were analyzed for levels of inflammatory markers, including adhesion molecules, chemokines and white blood cells.
It was found that both groups had lower levels the inflammatory marker interleukin-1, as well as decreased levels of fibrinogen, which is involved in blood clotting and is not a marker of inflammation. However, red wine was additionally associated with significantly lower levels of adhesion molecules, C-reactive protein, and monocyte and lymphocyte proteins involved in inflammation.
Gin lacks the polyphenols that are found in red wine which are believed to be responsible for the drink's benefits. Dr Rubin, who is a Professor of Pathology at Jefferson Medical College of Thomas Jefferson University, stated, “It's clear from these results that while drinking some form of alcohol lowers inflammatory markers, red wine has a much greater effect than gin.”
Better intensive care blood sugar control lowers mortality rates
A study appearing in the August 2004 issue of Mayo Clinic Proceedings reported that strictly controlling blood glucose lowers mortality patients in intensive care units (ICUs).
James Krinsley, MD, who is the director of critical care at The Stamford Hospital in Stamford, Connecticut, compared 800 patients admitted to the hospital's intensive care unit prior to the initiation of a glucose management protocol to 800 patients admitted after the protocol was adopted. The glucose management protocol specifies intensive monitoring of blood glucose and treating elevations of greater than 140 milligrams per deciliter with insulin.
The protocol was based on the work of Greet van den Berge, MD, PhD, of the University of Leuven in Lueven, Belgium, who found decreased mortality and less organ dysfunction in surgical ICU patients requiring ventilation who received intensive glucose management.
Earlier work by Dr Krinsley, inspired by the work of Dr van den Berge and also published in Mayo Clinic Proceedings, revealed a positive relationship between glucose levels and mortality in critically ill individuals. In the current study, Dr Krinsley observed a reduction in deaths of 29.3 percent in patients treated with the protocol compared to those who were admitted before the protocol was initiated, representing 49 lives. In addition, new cases of kidney failure, the need for blood transfusions, and length of intensive care stay were reduced in the treated patients.
The study is the first to demonstrate that intensive management of blood glucose reduces mortality among a general population of critically ill patients similar to those found in most intensive care units. Dr Krinsley predicted, "This is a low-cost, effective intervention that can profoundly affect patients. Intensive glucose management will eventually become a standard of care in ICUs (intensive care units) worldwide."
Iodine levels associated with IQ in children
A study conducted in Spain published in the August 2004 Journal of Clinical Endocrinology and Metabolism has found a positive relationship between iodine intake and intelligence quotient (IQ) in children between the ages of six and sixteen.
Piedad Santiago-Fernandez, MD, of the Unidad de Endocrinología, Complejo Hospitalario Ciudad de Jaén, and colleagues measured the urinary iodine levels of 1,221 southern European children to determine iodine intake. Dietary questionnaires and IQ tests were completed by all participants. The children were examined for the presence of goiter (a disease caused by iodine deficiency characterized by enlargement of the thyroid gland), and blood samples were analyzed for thyroid hormones.
Goiter was diagnosed in 19.4 percent of the children and was more prevalent in girls than boys. The mean IQ was 97.2 (average IQ is 100). Gender, education level and the presence of goiter had no effect on IQ, but iodine levels greater than 100 micrograms per liter were significantly associated with having a higher IQ. Compared to those whose urinary iodine levels were 150 micrograms per liter or higher, children with levels that were 25 micrograms per liter or less experienced more than double the risk of having an IQ in the lowest 25 percent.
When the diets of the children were analyzed, iodized salt and dairy product consumption were associated higher urinary iodine levels. The risk of having an IQ in the bottom one-fourth of participants was significantly associated with using non-iodized salt, and with consuming milk less than once per day as opposed to three times per day. Of children who used iodized salt, 4.4 percent had IQs below 70, compared to 8.2 percent of participants who did not use it. These results suggest that improving dietary iodine intake could enable many children to increase their IQ scores.
Vitamin D receptor gene variations increase the risk of breast and prostate cancer
Research published in the August 15 2004 issue of the American Association for Cancer Research journal Clinical Cancer Research, and the August issue of its sister journal, Cancer Epidemiology, Biomarkers & Prevention found that variations known as polymorphisms in the vitamin D receptor gene predisposed its carriers to increased risks of breast and prostate cancer.
In the study published in Clinical Cancer Research, researchers at St. George's Hospital Medical School in London found that Caucasian women who had certain variations in the vitamin D receptor gene had an increased risk of breast cancer as well as a greater risk of metastasis. Two of three known variants were found to double breast cancer risk, and while the third, called the F variant, was not associated with the risk of breast cancer, it greatly increased risk of the disease when coupled with one of the other genotypes as well as increased metastatic disease. In the study published in Cancer Epidemiology, Biomarkers & Prevention, the F variant was found to increase the risk of prostate cancer in African-American men who had two copies of the polymorphism. These men also had an increased risk of developing the advanced form of the disease. Caucasian men with these vitamin D receptor gene alterations did not experience a similar increase in prostate cancer risk. There were also fewer Caucasians who were found to have the polymorphism, providing a possible explanation for the comparatively greater incidence of prostate cancer in African-Americans.
It is known that vitamin D inhibits the growth of breast and prostate cancers, and that this is mediated by the vitamin D receptor. Identification of alterations in the gene for the vitamin D receptor may be useful in determining which men and women would particularly benefit from preventive therapies for these cancers.
Another virus found to play a role in cancer
The common BK virus, a polyomavirus which lives in the kidneys and remains inactive except in people with depressed immune function, may play a role in the development of prostate cancer according to research published July 19, 2004 online in the journal Oncogene (http://www.nature.com/onc/index.html). Scientists from the University of Michigan Medical School have discovered DNA and proteins from the BK virus in prostate tissue with abnormal changes known as atrophic lesions, which are precursors of prostate cancer.
The BK virus uses a protein known as Tantigen (TAg) to induce cell division in its host cell because the virus does not have enough genes to reproduce by copying its own DNA. However, by interrupting the normal cell cycle of the host cell to force it to divide, abnormal cell division is sometimes a result.
The researchers examined twenty-one prostate tissue samples obtained from men with prostate adenocarcinoma. The samples contained normal, precancerous and cancerous cells. The team found the BK virus in 71 percent of the samples, however TAg was present in only the atrophic lesions, and not in normal or cancerous tissue. They also found a protein made by the tumor suppressor gene p53 in the cell's cytoplasm. Lead researcher and professor of microbiology and immunology at the University of Michigan, Michael J. Imperiale, PhD, commented, "We know that for p53 to function as a tumor suppressor gene, its protein product must be in the cell's nucleus. TAg apparently sequesters p53 protein in the cell's cytoplasm, preventing it from entering the nucleus and giving the signal for the cell to stop dividing and die."
Dr Imperiale concluded, “Our results do suggest that the virus plays a role in the transition from normal to uncontrolled growth of prostate cells."
Tea drinking associated with reduced hypertension risk
In a study published in the July 26 2004 issue of the American Medical Association Journal Archives of Neurology, Taiwanese researchers found that drinking green or black tea was associated with a lower risk of developing high blood pressure.
The researchers, from the Medical College of National Cheng Kung University in Tainan, Taiwan, examined data collected from a community-based study of chronic diseases which enrolled 2,416 men and women in 1996. Medical examinations and interviews of the subjects were conducted upon enrollment to ascertain dietary habits, medical histories, blood pressure, and other information. Of these, 1,507 did not have a history of hypertension and were included in the current analysis.
Six hundred participants in the current study reported consuming 120 milliliters or more tea per day for at least one year. Individuals who consumed 120 to 599 milliliters tea per day experienced a 46 percent lower risk of having newly diagnosed hypertension than those who were nonhabitual tea drinkers. In those whose tea consumption was greater than 600 milliliters per day, the risk was 65 percent lower than non-tea drinkers. Drinking tea for longer than a year was not associated with greater benefits.
These findings contrast with that of a couple of short term studies that did not find a blood pressure lowering effect associated with tea consumption, indicating that longer periods of consumption may be necessary to elicit this benefit.
Tea contains theanine, which has lowered blood pressure in spontaneously hypertensive rats. The endothelial dysfunction involved in the development of hypertension may be reduced by the antioxidant activity of the polyphenols that occur in tea, offering an explanation for the decrease in high blood pressure risk found to be associated with tea consumption in this study.
Cystic fibrosis patients have lower nutrient levels, greater oxidative stress
A study published in the August 1 2004 issue of the American Journal of Clinical Nutrition (http://www.ajcn.org/) compared adults with cystic fibrosis (CF) to a healthy group of individuals and found that the CF patients had lower levels of several nutrients and higher indicators of oxidative stress.
In healthy people there is a balance between oxidation and antioxidant processes, but this balance is disturbed in people with cystic fibrosis. Impaired digestion and malabsorption diminish the available supply of antioxidant nutrients, and immune cells chronically stimulated by the disease as well as invading microorganisms increase the amount of free radicals produced in these patients. In the current study, researchers in Germany sought to determine if the changes in antioxidant status and oxidative stress were due to the progression of cystic fibrosis or merely an effect of age by comparing 22 CF patients of varying ages with 35 healthy controls.
Fasting blood samples were analyzed for beta-carotene, beta-cryptoxanthin, lycopene, alpha-tocopherol, vitamin C, and markers of oxidative stress. Buccal mucosal cell samples (obtained from the oral cavity) were analyzed to provide tissue levels of alpha-tocopherol. Breath condensate provided levels of F2 alpha-isoprostane, a marker of oxidation.
In the cystic fibrosis patients, plasma vitamin C, and plasma and tissue alpha-tocopherol decreased significantly with age. Plasma beta-carotene, beta-cryptoxanthin and lycopene were lower in participants with CF than in healthy subjects in all age groups. In CF patients over the age of eighteen, plasma and tissue alpha-tocopherol and plasma vitamin C were lower and oxidative stress markers higher than in controls in the same age group. The authors suggest that “innovative supplementation strategies should be applied to optimize the antioxidant status of patients with CF.”