ABSTRACTS

CATSKILL, NEW YORK. Patients with kidney failure require long-term hemodialysis in order to remove waste products from the blood. It is estimated that about 350,000 patients in the USA alone require regular dialysis treatments. Although modern dialysis methods are effective in cleaning up the blood they do produce side effects. Uremic pruritus or renal itch (localized or generalized itch in patients with chronic kidney disease) affects up to 80% of patients on dialysis. A recent clinical trial found that patients given 6 grams/day of fish oil had significantly less severe itching than did patients given a similar daily dose of olive oil or safflower oil.

The researchers doing the trial speculate that fish oils prevent itching by displacing arachidonic acid from cell membranes. Fish oils and arachidonic acid compete for the same enzymes (cyclooxygenase and lipoxygenase) used in the production of eicosanoids. If arachidonic acid "wins" more pro-inflammatory compounds (series 2 prostaglandins and series 4 leukotrienes) are produced whereas if fish oils gain the upper hand the result is the production of more anti-inflammatory compounds (prostaglandin E3 and leukotriene B5). The anti-inflammatory eicosanoids would be less likely to cause itching than would the pro-inflammatory ones.

Because dialysis patients leave some blood in the dialysis machine at each treatment they are given the hormone erythropoietin in order to stimulate the production of new red blood cells. A small pilot study involving 20 dialysis patients was recently carried out to see if fish oil supplementation would reduce the need for erythropoietin. The patients were given 6 grams/day of emulsified fish oil (3 pouches of Coromega) for 8 weeks. At the end of the study the average erythropoietin requirement had declined by 16% and serum albumin had increased by 3.6%.

Researchers at Emory University have found that dialysis patients who reported eating fish at least once in a 3- day period were about half as likely to die during the 3-year study period, as were patients who did not report any fish consumption.

Fish oils are generally considered safe in daily intakes of as much as 12 grams. According to the Food and Drug Administration supplementing with EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid), the main components of fish oil, is safe provided the combined daily intake does not exceed 3 grams. (Note: This would correspond to about 10 grams of fish oil). There is no evidence that fish oils increase bleeding time; however, it would be prudent to adjust the dose of heparin used during dialysis if fish oil supplementation is used.
Vergili-Nelsen, JM. Benefits of fish oil supplementation for hemodialysis patients. Journal of the American Dietetic Association. Vol. 103, September 2003, pp. 1174-77

BERLIN, GERMANY. Hypertension (high blood pressure) is a major cause of cardiovascular disease and mortality. Mild hypertension can usually be controlled with diet, but more severe cases require life-long drug therapy. Researchers at Humboldt University now report that regular exercise is as effective in controlling hypertension, as are most commonly used medications. Their experiment included 10 men (average age of 43 years) with mild hypertension at rest (systolic BP of 130-159 mm Hg and/or diastolic BP of 85-99 mm Hg) and elevated blood pressure during standardized ergometric testing (systolic BP above 200 mm Hg and/or diastolic BP above 100 mm Hg at 100 W). The participants were all non-smokers and none received any medications.

The exercise program consisted of two outdoor training sessions supervised by a physician and a qualified instructor. The program started out slowly with just 5-30 minutes of slow running per session, but after about 5 months the participants were running for an hour twice a week. Six months after the training began average systolic BP during exercise had dropped from 188 mm Hg to 170 mm Hg and average diastolic BP had decreased from 107 mm Hg to 100 mm Hg. Blood pressure readings during rest had not changed. However, after 3 years of regular training average resting systolic BP (in supine position) had dropped from 151 mm Hg to 130 mm Hg and average diastolic BP from 96 to 87 mm Hg. Systolic pressure during exercise dropped from 188 to 167 mm Hg and diastolic pressure from 106 to 92 mm Hg after 3 years of twice-weekly training.

The researchers point out that the 9.2% decrease in systolic BP achieved after 3 years corresponds favourably with that obtained by using medications like prazosin (3.2% reduction), diuretics (4.3%), gallopamil (4.4%) and enalapril (6.2%). However, the reduction achieved with beta-blockers (16.6%) is still superior to that achieved by exercise. The researchers conclude that regular exercise has a beneficial effect on hypertension and that pharmacological treatment can be deferred or probably prevented in hypertensive subjects who regularly engage in aerobic sports activities.
Ketelhut, RG, et al. Regular exercise as an effective approach in antihypertensive therapy. Medicine & Science in Sports & Exercise, Vol. 36, January 2004, pp. 4-8

KNOXVILLE, TENNESSEE. Pedometers are becoming increasingly popular for measuring physical activity level throughout the day. Although they do not measure physical activity such as swimming, weightlifting, bicycling, etc. they are very useful in measuring physical activity involved in walking. Pedometers are small, simple to operate and are typically worn on the belt or waistband during the day.

Considerable research has been done to determine the association between daily pedometer readings (total steps taken during the day) and physical activity level. Less than 5000 steps/day classifies one as sedentary, 5000 – 7499 as inactive, 7500 – 9999 as somewhat active, and greater than 10,000 steps/day as active. Walking a mile is equivalent to taking about 2000 – 2500 steps. Research has shown that taking 10,000 steps/day is enough to provide significant cardiovascular disease protection and, in the process, expends at least 333 kcal/day. Other research has shown that expending this amount of energy (more than 2000 kcal/week) protects against heart attack.

There are many different pedometers on the market and medical researchers at the University of Tennessee now report that not all of them are accurate. They evaluated the following 13 models – Accusplit Alliance 1510, Freestyle Pacer Pro, Colorado on the Move, Kenz Lifecorder, New-Lifestyles NL-2000, Omron HJ-105, Oregon Scientific PE316CA, Sportline 330 and 345, Walk4Life LS 2525, Yamax Skeletone EM-180, and Yamax Digi- Walker SW-200 and SW-701.

The different pedometers were worn by a group of 10 men and 10 women of varying bodyweights and heights. Each one was worn by each participant for a day (on the right hip) while the reference pedometer (Yamax Digi- Walker YX-200) was worn on the opposite hip. Extensive research has shown that the YX-200 is highly accurate in measuring actual steps taken. The average number of steps taken by the group was 9244 per day.

The researchers determined the accuracy of the pedometers by comparing their readings to those of the YX- 200. They found that the following pedometers were highly accurate – Kenz Lifecorder, New-Lifestyles NL- 2000, Yamax Digi-Walker SW-200 and SW-701, and the Sportline 330. The Colorado on the Move and Sportline 345 pedometers were accurate to within 10% of the reference, but the rest of the pedometers were quite inaccurate. The Oregon Scientific PE 316CA overestimated the number of steps taken in a day by 45% while the Freestyle Pacer Pro underestimated them by 25%. It is clear that pedometers are useful for measuring physical activity level, but clearly this usefulness is compromised if they are not accurate.

Separate research has shown that pedometers fail to accurately measure steps taken among populations of elderly, frail, nursing home residents suffering from various gait disorders associated with chronic health conditions. Even otherwise accurate pedometers underestimate the number of steps taken in this group of people by anywhere from 46 to 74% depending on walking speed (inaccuracy is greatest at slow walking speeds).
Schneider, PL, et al. Pedometer measures of free-living physical activity: comparison of 13 models. Medicine & Science in Sports & Exercise, Vol. 36, February 2004, pp.331-35
Cyarto, EV, et al. Pedometer accuracy in nursing home and community-dwelling older adults. Medicine & Science in Sports & Exercise, Vol. 36, February 2004, pp.205-09

CHICAGO, ILLINOIS. High levels of the omega-3 fatty acid docosahexaenoic acid (DHA) are found in the more active areas of the brain including the cerebral cortex, mitochondria, synaptosomes, and synaptic vesicles. At least one epidemiologic study has shown that patients with Alzheimer's disease (AD) have significantly lower levels of omega-3 fatty acids in their plasma phospholipids than do age-matched controls. Researchers at the Rush-Presbyterian-St. Luke's Medical Center now report that older people can reduce their risk of developing AD by increasing their intake of fish and fish oil (DHA). Their study included 815 men and women over the age of 65 years who had showed no sign of AD during a thorough baseline examination. About 2 years after the examination all participants completed a 154-item food frequency questionnaire and provided information about their current use of supplements. After another 2 years all participants were again subjected to a thorough, structured neurologic clinical evaluation to establish the presence or absence of AD. A total of 131 study participants were found to have developed AD over the 3.9-year follow-up period.

The researchers found that participants who consumed fish just once a week had a 60% lower risk of developing AD than did those who rarely or never ate fish. They also observed that participants whose daily intake of DHA was about 100 mg/day had an incidence of AD which was 70% lower than those with an intake of 30 mg/day or less.

Eicosapentaenoic acid (EPA), another component of fish oil, showed no appreciable effect; however, the maximum intake was only 30 mg/day. A high total intake of omega-3 fatty acids was also strongly correlated with a reduced risk for AD. Participants with an intake of 1.6 – 4.1 grams/day had a 70% lower risk than those with an intake below 1.05 grams/day. Alpha-linolenic acid (flaxseed oil) intake was not associated with AD risk except in the case of people with the APOE-epsilon 4 allele where a high intake was strongly protective. The researchers conclude that an increased intake of fish or omega-3 fatty acids, especially DHA, can substantially reduce the risk of developing Alzheimer's disease.
Morris, MC, et al. Consumption of fish and n-3 fatty acids and risk of incident of Alzheimer's disease. Archives of Neurology, Vol. 60, July 2003, pp. 940-46
Friedland, RP. Fish consumption and the risk of Alzheimer disease. Archives of Neurology, Vol. 60, July 2003, pp. 940- 46

Editor's comment: High doses of fish oils should always be accompanied by vitamins E and C in order to prevent oxidation of the oil.

BOSTON, MASSACHUSETTS. Multiple sclerosis (MS) is the most common demyelinating disease. It involves damage to myelin sheaths (the "insulation" covering certain nerve fibers) in the central or peripheral nervous system. The lesions caused by MS can be observed by a MRI scan of the brain. Some observers have noted that the extent of the lesions varies from time to time with more extensive lesions being present in the winter months than in the summer months.

Researchers at the Harvard School of Public Health now report that MS may be associated with a vitamin D deficiency and that vitamin D supplementation may help prevent it. The researchers followed a large group of 92,253 female nurses from 1980 to 2000 and another large group of 95,310 female nurses from 1991 to 2001. During this time, 173 cases of MS were diagnosed giving an incidence rate of 7.4 cases per 100,000 person- years.

The nurses had completed food frequency questionnaires every 4 years and had also reported on their use of supplements. Analysis of the data showed that women with a high intake of vitamin D had a 33% lower incidence of MS than did women with low intakes. Further analysis revealed that vitamin D from food sources, mainly milk and fish, contributed very little to overall vitamin D intake and was not, on its own, associated with a decreased risk of MS. Vitamin D from supplements, however, was highly correlated with MS risk. Participants with a vitamin D intake from supplements of 400 IU/day or more had a 40% lower risk of MS than did women who did not supplement. Most of the vitamin D came from multivitamins, so it is possible that other components in the multivitamins could have had a protective effect. However, the researchers believe that vitamin D is the protective agent. They point out that the prevalence of MS increases with distance from the equator in both hemispheres indicating that sunlight, a potent initiator of endogenous vitamin D production, may exert an important protective effect. Several studies have found that MS patients tend to be vitamin D deficient. Vitamin D deficiency is particularly prevalent at latitudes above 42 degrees where blood levels in the winter may drop to half of that observed during the summer months.

The researchers conclude that vitamin D helps protect against MS and urge clinical trials to determine whether vitamin D supplementation may also help slow the progression of the disease.
Munger, KL, et al. Vitamin D intake and incidence of multiple sclerosis. Neurology, Vol. 62, January 2004, pp. 60- 65

Editor's comment: The evidence that a vitamin D deficiency is an important factor underlying many diseases is growing rapidly. Supplementing with 1000 IU/day during the winter months is inexpensive and may well be one of the most effective disease preventing measures available, especially for people living above (or below) 42 degrees latitude.

OXFORD, UNITED KINGDOM. It is estimated that about 14% of total radiation exposure worldwide is attributable to medical x-rays. This figure is undoubtedly significantly higher in developed countries where modern diagnostic facilities are more abundant. It is known and accepted that any exposure to ionizing radiation (x-rays) increases the risk of cancer. What is less clear and still somewhat controversial is just how significant the risk increase actually is. Researchers at the University of Oxford have just completed a major study to attempt to shed light on this question. Their report makes sobering reading indeed.

The researchers estimated cancer risk based on known cancer rates and exposure to medical x-rays in 14 developed countries including Canada, Australia, Germany, Sweden, Switzerland, the UK, and the USA. They used exposure-based risk estimates based on populations exposed to known doses such as Japanese atomic bomb survivors. All exposure data are expressed in milliGray (mGy), which is a measure of the energy deposited in the tissue by the radiation beam. One mGy is equivalent to 1 milliSievert (mSv) in the case of medical x-rays. The researchers estimated organ-specific radiation doses by type of diagnostic x-ray. These varied from 0.00 mGy in the case of bladder exposure from a chest x-ray to 43.9 mGy in the case of thyroid exposure from a CT scan of the cervical spine. Table 1 depicts organ exposures in excess of 10 mGy caused by different x-ray techniques. NOTE: The Canadian Safety Board has set an upper limit on overall annual radiation exposure of 1 mSv and US authorities have set an annual limit of 50 mSv for specific organ exposure.

A mammogram produces a breast radiation exposure of 2.0 mGy (per view) and a dental x-ray (wing bite) yields a radiation exposure of about 0.1 mGy. It is clear that the radiation exposure involved in diagnostic x-rays can be substantial and should be avoided whenever possible. In some cases it may also be possible to substitute a high radiation procedure (eg. barium enema) with an alternative low-risk procedure (eg. colonoscopy).

The researchers found that radiation exposure contributed 0.6% to the overall cancer incidence in the 14 countries surveyed. However, for Japan, where more procedures are done, the risk contribution was 3.2% while it reached 0.9% in the US due to higher doses used per procedure in an attempt to get clearer images.

Table 2 shows the estimated lifetime risk (to age 75 years) attributable to diagnostic x-rays.

The researchers estimate that coronary angiography accounts for 280 cases of cancer per million examinations, cerebral angiography for 180 cases, and barium enema for 170 cases. German radiologists, in commenting on the study, conclude that, "Up to 30% of chest x-rays may not be indicated; unnecessary CT examination can lengthen hospital stay as well as causing radiation exposure. In everyday practice, those ordering radiological procedures should think carefully about the benefit for and the risk of their patients for each examination."
Berrington de Gonzalez, A and Darby, S. Risk of cancer from diagnostic x-rays: estimates for the UK and 14 other countries. The Lancet, Vol. 363, January 31, 2004, pp. 345-51
Herzog, P and Rieger, CT. Risk of cancer from diagnostic x-rays. The Lancet, Vol. 363, January 31, 2004, pp. 340- 41

Editor's comment: While the overall cancer risk attributable to medical x-rays is fairly low it is certainly clear that patients who undergo several procedures can accumulate a substantial risk. It should be kept in mind that the tissue damage induced by x-rays does not diminish with the passage of time, but remains for life. It is possible to significantly reduce x-ray-induced radiation damage by supplementing with 30 mg/day of beta- carotene for at least a week prior to x-ray exposure[1].
[1] Umegaki, K, et al. Beta-carotene prevents x-ray induction of micronuclei in human lymphocytes. American Journal of Clinical Nutrition, Vol. 59, February 1994, pp. 409-12

SEATTLE, WASHINGTON. Iron is an important player in oxidative stress, a process that in turn may cause degeneration of dopaminergic neurons, a key feature of Parkinson's disease (PD). Increased iron levels have also been detected in the substantia nigra of patients with PD. Researchers at the University of Washington School of Medicine now report a strong association between the intake of iron and the risk of developing PD. Their study involved 250 newly diagnosed PD patients and 388 healthy controls. All participants were interviewed to determine their eating habits and use of vitamin supplements. The researchers found that the incidence of PD in the group (quartile) with the highest iron intake was 70% higher than in the group with the lowest intake. A similar association was found for manganese. Participants with a high intake of both iron and manganese were found to have a 90% higher incidence of PD than that found among those with a low intake of both these minerals. The researchers point out that many foods that are high in manganese are also high in iron; these include spinach, lima beans, peas, wheat bread, peanuts and other nuts and seeds.

The researchers found no association between fat intake and PD risk nor did they observe any correlation with the intake of vitamin C, vitamin E, beta-carotene or selenium. However, a high intake of lycopene was associated with a statistically significant, but unexplained, 40% increase in PD risk. The researchers urge further studies to confirm the observed association between PD risk and the intake of iron and manganese.
Powers, KM, et al. Parkinson's disease risk associated with dietary iron, manganese, and other nutrient intakes. Neurology, Vol. 60, June 2003, pp. 1761-66

NEWSBRIEFS

Tap water and contact lenses don't mix.
British researchers have found that tap water can contain an amoeba called Acanthamoeba, which can cause severe ulceration of the cornea, extreme pain, and possibly blindness. Acanthamoeba is not likely to be a problem in water systems with good flow, but could be if water is allowed to become stagnant in cold-water storage tanks or cisterns. Wearers of contact lenses should be particularly aware of the problem. They should avoid storing lenses in tap water, handling lenses with wet hands, and washing their face while wearing contact lenses.
New Scientist, January 15, 2004, p. 15

Inexpensive remedy for "sick" buildings.
Hermetically sealed buildings, and airplanes and cruise ships for that matter, are prime breeding grounds for airborne microbes associated with the common cold, flu, pneumonia, and similar diseases. Researchers at McGill University in Montreal now report that the incidence of respiratory diseases among office workers in sealed office buildings can be reduced by 40% by simply sterilizing the circulating air with ultraviolet light. The researchers estimate that the system would cost $52 per worker to install and $14/year per worker to operate and conclude, "If you reduced absenteeism due to building- related illness by one day per year in each worker, the system would pay for itself in less than six months."
New Scientist, December 6, 2003, p. 20

Promising new test for BSE.
At the moment it is only possible to confirm the presence of mad cow disease (BSE) through an autopsy. Researchers at the Robert Koch Institute in Berlin have announced the development of a new test, using infrared spectroscopy, which can detect BSE and its human form vCJD from a blood sample taken from a live animal or human. The test correctly identified BSE in 96% of samples tested from animals known to have the disease and did not find BSE in 92% of animals known to be free of the disease.
New Scientist, December 6, 2003, p. 20

Do medicinal herbs have a future?
Most people around the globe use herbal medicine for their normal health care relying on some 50,000 different medicinal plants to cure their ills and maintain their health. About two thirds of all herbs are harvested from the wild and there are now indications that between 4000 and 10,000 of them are endangered. Two forces are driving the path to extinction; the encroachment of farming and human habitation upon the traditional herb growing areas, and the tremendous demand for herbal products in North America and Europe. Harvesting of wild herbs is often the main source of income for poor people in China and India, and no attempts are being made to replant what is being harvested. One popular remedy, Prunus africana, which is used to prevent prostate enlargement, is headed towards the endangered list due to over- harvesting. Environmentalists urge herb suppliers to ensure that their harvest is sustainable by replanting what they harvest.
New Scientist, January 10, 2004, pp. 10-11

Memory problems associated with statin drugs.
Beatrice Golomb, a researcher at the University of California in San Diego has documented at least 100 cases of memory problems associated with the use of cholesterol-lowering statin drugs. One case involved a former astronaut on atorvastatin (Lipitor) who came back from a walk and failed to recognize his wife. He was OK when he discontinued the drug, but when he started back on Lipitor again he had another bout of amnesia. This time he could not remember his children. Researchers at Duke University report another 60 cases of memory problems associated with the use of statin drugs. Danish researchers have found that patients on statins have an increased risk of developing polyneuropathy, a condition characterized by weakness and numbness in the extremities. Although statin drugs are generally considered safe and millions of people are taking them every day, it is well to be aware of these potential side effects.
New Scientist, December 6, 2003, p. 14

RESEARCH REPORT

by Maurice McKeown, BDS, PhD