All Posts tagged fish

Omega-3 foods prevent eye disease

Eating a diet rich in omega-3 fatty acids appears to protect seniors against the onset of a serious eye disease known as age-related macular degeneration (AMD).  Researchers did a fresh analysis of a one-year dietary survey conducted in the early 1990s. The poll involved nearly 2,400 seniors between the ages of 65 and 84 living in Maryland’s Eastern Shore region, where fish and shellfish are eaten routinely.

While participants in all groups, including controls, averaged at least one serving of fish or shellfish per week, those who had advanced AMD had consumed less fish and seafood containing omega-3 fatty acids. After their food intake was assessed, participants underwent eye examinations. About 450 had AMD, including 68 who had an advanced stage of the disease, which can lead to severe vision impairment or blindness. Prior evidence suggested that dietary zinc is similarly protective against AMD, so the researchers looked to see if zinc consumption from a diet of oysters and crabs reduced risk of AMD, but no such association was seen.

The researchers believe that the low dietary zinc levels relative to zinc supplements could account for the absence of such a link. However, they cautioned against people to start taking omega-3 supplements to protect against AMD based on this study because they are not sure that the above results have sufficient power to draw any conclusions. The correlation is important but larger studies with longer term follow-up are needed before being able to properly assess the impact.

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Fish diet lowers risk of stroke

Fish diet lowers risk of stroke

Women who eat more than three servings of fish per week are less likely to experience a stroke, a new study suggests. Specifically, fish-lovers in Sweden were 16 percent less likely to experience a stroke over a 10-year-period, relative to women who ate fish less than once a week. “Fish consumption in many countries, including the U.S., is far too low, and increased fish consumption would likely result in substantial benefits in the population,” said Dr. Dariush Mozaffarian of the Harvard School of Public Health. When choosing fish to eat, it’s best to opt for fish that are rich in omega-3 fatty acids, found most abundantly in fatty fish like salmon, mackerel and albacore tuna. “But any fish is better than none,” Mozaffarian noted.

 

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“Indeed, these fatty acids likely underlie the benefits of fish on stroke risk”, said study author Dr. Susanna Larsson of the Karolinska Institute in Stockholm. “These fatty acids may reduce the risk of stroke by reducing blood pressure and blood (fat) concentrations.”

This is not the first study to suggest that people who eat more fish have a lower risk of stroke, and experts already recommend a fishy diet to reduce the risk of cardiovascular problems, Mozaffarian added. “This study supports current recommendations.” Earlier this year, for instance, a study showed that middle-aged and older men who eat fish every day are less likely than infrequent fish eaters to develop a suite of risk factors for heart disease, diabetes and stroke.

In the current study, published in the American Journal of Clinical Nutrition, Larsson and her colleagues looked at 34,670 women 49 to 83 years old. All were free of cardiovascular disease and cancer at the beginning of the study, in 1997. During 10 years of follow-up, 1,680 of the women (4 percent) had a stroke. Stroke caused by blockage of an artery that supplies blood to the brain — also known as a “cerebral infarction” or “ischemic stroke” — was the most common event, representing 78 percent of all strokes in the study. Other types of strokes were due to bleeding in the brain, or unspecified causes.

Women who ate more than three servings of fish per week had a 16 percent lower risk of stroke than women who ate less than one serving a week. “Not a small effect,” Mozaffarian said, noting that it was roughly equivalent to the effect of statin drugs on stroke risk. Furthermore, the researchers asked women about their diets only once, using a questionnaire, which might have caused errors that would underestimate the link between a fishy diet and stroke risk, he explained. “So, the true risk reduction may be larger.”

Interestingly, women appeared to benefit most from eating lean fish, when other research shows fatty fish is better for health. This finding may stem from the fact that most fatty fish, such as herring and salmon, is eaten salted in Sweden, Larsson explained. “A high intake of salt increases blood pressure and thus may increase the risk of stroke,” she said. “So the protective effects of fatty acids in fatty fish may be attenuated because of the salt.”

Indeed, when it comes to fish, not all have equal benefits, Mozaffarian noted – for instance, he said, research has not shown any cardiovascular benefits from eating fast food fish burgers or fish sticks. In addition, women of childbearing age should avoid certain types of fish known to carry relatively high levels of pollutants, such as shark and swordfish, Mozaffarian cautioned. “This is a very, very short list of fish to avoid or minimize — there are many, many other types of fish to consume,” he said. “Women at risk of stroke are generally beyond their child-bearing years, and so for these women, all types of fish can be consumed.”

Larsson and her team speculate that certain nutrients in fish, such as fatty acids and vitamin D, might explain its apparent benefits. The Swedish study cannot prove cause and effect for high fish consumption and lowered stroke risk, however. For instance, fish consumption could be a sign of a generally healthier lifestyle or some other mechanism at work. Last December, Larsson and colleagues published data from the same group of women in the journal Stroke showing that those who eat a lot of red meat may also be putting themselves at increased risk of stroke.

SOURCE: bit.ly/dKunk8 American Journal of Clinical Nutrition, online December 29, 2010.

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Mediterranean Diet May Keep Aging Mind Sharp

A new study shows following a Mediterranean style diet rich in vegetables, olive oil, and fish may keep the mind sharp and slow age-related cognitive decline.The diet typified by the Italians, Greeks, and other Mediterranean cultures has already been shown to reduce the risk of heart disease, diabetes, and some types of cancer. But this and other studies are now suggesting that the diet may also have healthy benefits for the mind.

The Mediterranean diet emphasizes fruits and vegetables, fish, legumes, non-refined cereals, olive oil, and moderate wine consumption, usually at meals. Researchers found older adults who followed the diet more closely had slower rates of age-related cognitive decline than those who didn't, even after adjusting for other factors such as educational level. “The more we can incorporate vegetables, olive oil, and fish into our diets and moderate wine consumption, the better for our aging brains and bodies,” says Christy Tangney, PhD, associate professor of clinical nutrition at Rush University, in a news release.

In the study, published in the American Journal of Clinical Nutrition, researchers analyzed information gathered by the ongoing Chicago Health and Aging Project, which follows 3,759 adults over the age of 65 living on the South Side of Chicago. Every three years, the participants took tests of memory and basic math skills and filled out a questionnaire on how often they eat 139 different foods. The study follow-up time was 7.6 years on average.

Researchers looked at how closely the participants followed a Mediterranean diet and then compared it to their scores on age-related cognitive decline. Out of a maximum score of 55 for total adherence to a Mediterranean diet, the average score was 28. The results showed those with higher than average scores had a slower rate of age-related mental decline than those with lower scores. Researchers also looked at how closely the participants followed the Healthy Eating Index-2005, which is based on the 2005 Dietary Guidelines for Americans. They found no relationship between adherence to this type of diet and the rate of age-related cognitive decline.

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Stroke deaths higher where fried fish aplenty

The steep rate of death from stroke in a swath of Southern states often referred to as America's “stroke belt” may be linked to a higher consumption of fried fish in that region, new research suggests. A study published in the journal Neurology shows people living in the stroke belt — which comprises North Carolina, South Carolina, Georgia, Alabama, Mississippi, Tennessee, Arkansas and Louisiana — eat more fried fish and less non-fried fish than people living in the rest of the country, and African-Americans eat more fried fish than Caucasians. “Differences in dietary fish consumption, specifically in cooking methods, may be contributing to higher rates of stroke in the stroke belt and also among African Americans,” says study author Fadi Nahab, medical director for the Stroke Program at Emory University Hospital in Atlanta.

The research, part of a large government-funded study, Reasons for Geographic and Racial Differences in Stroke (REGARDS), involved 21,675 participants from across the country; the average age was 65. Of the participants, 21% were from the “stroke buckle,” the coastal plain region of North Carolina, South Carolina and Georgia where stroke mortality rates are even higher than they are in the rest of the stroke belt. Another 34% were from the rest of the stroke belt and 44% were from the other states.

Participants were interviewed by phone and then given an in-home physical exam. The questionnaire asked how often they ate oysters, shellfish, tuna, fried fish and non-fried fish. The American Heart Association recommends people eat fish high in omega-3 fatty acids—essential fatty acids humans get through their diet—at least twice a week, baked or grilled but not fried. Fewer than one in four overall ate two or more servings of non-fried fish a week. Stroke belt residents were 32% more likely to eat two or more servings of fried fish each week than those in the rest of the country.

African-Americans were more than 3.5 times more likely to eat two or more servings of fried fish each week than Caucasians, with an overall average of about one serving per week of fried fish compared with about half a serving for Caucasians. When it came to eating non-fried fish meals, stroke belt residents ate an average of 1.45 servings per week, compared with 1.63 servings eaten by people elsewhere.

“This is good stuff. It's a well-done study, but I think one thing to bear in mind is that it's not specifically a study of stroke risk. You're looking at a community and seeing how it's behaving on the whole,” says Daniel Labovitz, a stroke neurologist at Montefiore Medical Center in the Bronx. “This study can't tell you causation. It can't tell you there's a direct link between one thing and another, it just tells you they're associated,” says stroke neurologist Victor Urrutia, an assistant professor at Johns Hopkins University School of Medicine.

How might eating fried fish impact stroke?

It could be that frying the fish leaches out the omega-3s, says Jeremy Lanford, stroke director at Scott & White Healthcare in Roundrock, Texas. Or the increased fat calorie content from the frying oil may contribute to stroke, says author Nahab. He also notes that fish used for frying, such as cod and haddock, tend to be the types lower in healthy fats. More research is needed to tease out whether cooking methods affect stroke risk, Labovitz says. “In other words, is fried fish a problem, or is it another red herring?” he says.

The study was supported by the National Institute of Neurological Disorders and Stroke, the National Institutes of Health, and the Department of Health and Human Services. Funding was provided by General Mills for coding of the food frequency questionnaire.

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New Evidence for Eye-Protective Effects of Omega-3-Rich Fish, Shellfish

Researchers at Wilmer Eye Institute, Johns Hopkins School of Medicine, wanted to know how the risk of age-related macular degeneration (AMD) would be affected in a population of older people who regularly ate fish and seafood, since some varieties are good sources of omega-3 fatty acids. A diet rich in omega-3s probably protects against advanced AMD, the leading cause of blindness in whites in the United States, according to the Age-Related Eye Disease Study (AREDS) and other recent studies. High concentrations of omega-3s have been found in the eye's retina, and evidence is mounting that the nutrient may be essential to eye health. The new research, led by Sheila K. West, PhD, was part of the Salisbury Eye Evaluation (SEE) study.

Food intake information with details on fish and shellfish consumed was collected over one year using a validated questionnaire for 2,391 participants aged 65 to 84 years who lived along Maryland's Eastern Shore. After dietary assessment was complete, participants were evaluated for AMD. Those with no AMD were classified as controls (1,942 persons), 227 had early AMD, 153 had intermediate-stage disease, and 68 had advanced AMD. In the advanced AMD group, the macular area of the retina exhibited either neovascularization (abnormal blood vessel growth and bleeding) or a condition called geographic atrophy. Both conditions can result in blindness or severe vision loss.

“Our study corroborates earlier findings that eating omega-3-rich fish and shellfish may protect against advanced AMD.” Dr. West said. “While participants in all groups, including controls, averaged at least one serving of fish or shellfish per week, those who had advanced AMD were significantly less likely to consume high omega-3 fish and seafood,” she said.

The study also looked at whether dietary zinc from crab and oyster consumption impacted advanced AMD risk, but no significant relationship was found. Zinc is also considered protective against AMD and is included in an AMD-vitamin/nutrient supplement developed from the AREDS study. Dr. West speculated that her study found no effect because the levels of zinc obtained from seafood/fish were low compared to supplement levels.

The research is published in the December issue of Ophthalmology, the journal of the American Academy of Ophthalmology.

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Can Omega-3 foods prevent eye disease in seniors?

Eating a diet rich in omega-3 fatty acids appears to protect seniors against the onset of a serious eye disease known as age-related macular degeneration (AMD), a new analysis indicates.”Our study corroborates earlier findings that eating omega-3-rich fish and shellfish may protect against advanced AMD,” study lead author Sheila K. West, of the Wilmer Eye Institute at Johns Hopkins School of Medicine in Baltimore, said in a news release from the American Academy of Ophthalmology.

“While participants in all groups, including controls, averaged at least one serving of fish or shellfish per week, those who had advanced AMD were significantly less likely to consume high omega-3 fish and seafood,” she added.

The observations are published in the December issue of Ophthalmology.

West and her colleagues based their findings on a fresh analysis of a one-year dietary survey conducted in the early 1990s. The poll involved nearly 2,400 seniors between the ages of 65 and 84 living in Maryland's Eastern Shore region, where fish and shellfish are eaten routinely. After their food intake was assessed, participants underwent eye exams. About 450 had AMD, including 68 who had an advanced stage of the disease, which can lead to severe vision impairment or blindness. In the United States, AMD is the major cause of blindness in whites, according to background information in the news release.

Prior evidence suggested that dietary zinc is similarly protective against AMD, so the researchers looked to see if zinc consumption from a diet of oysters and crabs reduced risk of AMD, but no such association was seen. However, the study authors theorized that the low dietary zinc levels relative to zinc supplements could account for the absence of such a link.

Anand Swaroop, chief of the neurobiology, neuro-degeneration, and repair laboratory at the U.S. National Eye Institute, interpreted the findings with caution. “It does make huge sense theoretically,” he said. “Photoreceptors have a very high concentration of a specific type of fatty acids and lipids, relative to many other cell types. So it would make sense that omega-3 consumption would be beneficial. The theory is sound.”

“However, I wouldn't want people to start taking grams of omega-3 to protect against AMD based on this finding because I'm not really sure that this study has sufficient power to draw any conclusions,” Swaroop added. “This is just a one-year analysis and AMD is a long-term disease. The correlation is important, and it should be explored further. But we need larger studies with longer term follow-up before being able to properly assess the impact.”

SOURCE: Anand Swaroop, Ph.D senior investigator and chief of neurobiology, neurodegneration, and repair laboratory, U.S. National Eye Institute, Bethesda, Md.; American Academy of Ophthalmology, news release, Dec. 1, 2010

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Fish oil enhances effect of Green Tea on Alzheimers

Fish oil, when combined with epigallocatechin‑3‑gallate (EGCG—a polyphenol and antioxidant found in green tea), may affect chemical processes in the brain associated with Alzheimer's disease, according to a study published in Neuroscience Letters. This study, which used an animal (mouse) model of Alzheimer's disease, builds on previous research linking the disease to peptides (amino acid chains) called beta‑amyloids and laboratory studies suggesting that EGCG decreases memory problems and beta‑amyloid deposits in mice.

Researchers from the University of South Florida divided Alzheimer's disease‑model mice into five feeding groups. During a period of 6 months, each group was fed one of five diets: fish oil only; high‑dose EGCG; low‑dose EGCG; low‑dose EGCG and fish oil; or a regular diet (control). The researchers observed that low‑dose EGCG alone did not reduce the Alzheimer's disease-related chemical processes in the brain. However, the mice fed the combination of fish oil and EGCG had a significant reduction in amyloid deposits that have been linked with Alzheimer's disease.

Upon examination of blood and brain tissues of the mice, the researchers found high levels of EGCG in the mice that were fed the combination of fish oil and low‑dose EGCG compared with those fed low‑dose EGCG alone. A possible explanation, according to the researchers, is that fish oil enhances the bioavailability of EGCG—that is, the degree to which EGCG was absorbed into the body and made available to the brain. This effect, in turn, may contribute to the increased effectiveness of this combination. Further research is necessary, however, to determine if the combination of fish oil and EGCG affects memory or cognition, and whether it might have potential as an option for people at risk of developing Alzheimer's disease.

Reference

Giunta B, Hou H, Zhu Y, et al. Fish oil enhances anti‑amyloidogenic properties of green tea EGCG in Tg2576 mice. Neuroscience Letters. 2010;471(3):134–138.

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Red meat raises heart attack risk

Eating red meat and processed meats like bacon sharply increased heart disease risk in women, U.S. researchers say.Researchers at Harvard School of Public Health in Boston suggest eating healthier protein-rich foods — such as fish, poultry, low-fat dairy and nuts — instead of red and processed meats, may reduce heart disease risk.

“There are good protein-rich sources that do not involve red meat,” first author Dr. Adam Bernstein says in a statement. “You don't need to have hot dogs, hamburgers, bologna or pastrami, which are all fresh or processed meats.”

The study, published in the journal Circulation: Journal of the American Heart Association, finds women having two servings per day of red meat had a 30 percent higher risk of developing coronary heart disease than those who had half a serving per day.

The risk of heart disease was lowered 30 percent when a daily serving of red meat was replaced by nuts. Another red-meat replacement — fish — lowered cardiac risk 24 percent and poultry reduced heart risk by 19 percent.

Bernstein and colleagues examined medical history and lifestyle — including diet — for 84,136 women, ages 30-55, enrolled the Nurses' Health Study from 1980 to 2006. During the 26-year period, the researchers documented 2,210 non-fatal heart attacks and 952 deaths from coronary heart disease.

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Eating a sensible diet improves lung health

Steering clear of full-fat, fried, and processed foods is not just good for overall health, it could help prevent chronic lung conditions, a large UK study has revealed.

Led by Seif Shaheen, Professor of Respiratory Epidemiology at Barts and The London School of Medicine, the study – involving 1,551 men and 1,391 women with an average age of 66 – showed that those whose diet favoured fresh fruit and vegetables, oily fish and wholegrain products had far better lung function than those who chose a diet high in fat, sugar and processed food.

The diets of those involved were investigated to assess what kinds of food they consumed on a regular basis. Their lung function was also tested using a spirometer, a device which measures the amount of air that a person can blow out of their lungs in one second. This simple test illustrates how healthy the lungs are, and determines whether any blockage or obstruction exists in the airways. If the airways are obstructed, the person is diagnosed with Chronic Obstructive Pulmonary Disease (COPD).

The study also revealed that the beneficial effects of the sensible diet were particularly strong in men who smoked.

Lung health in particular may be positively affected by a sensible diet because of the antioxidants contained in fruit and wholegrains, and the omega-3 fatty acids found in oily fish – that protect the lungs against the adverse effects of smoking.

Professor Shaheen said: “Whilst cessation of smoking is still the number one way to improve lung health, this study is important because it suggests that cases of COPD might be prevented if people, especially male smokers, ate more fruit and vegetables, oily fish and wholegrain cereals, and less white bread, sugar, full fat dairy products, fried food and processed meat. However, the only way to confirm this would be to carry out a randomised controlled trial.”

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Mediterranean Diet Tied to Lower Breast Cancer Risk

Researchers have long speculated that the diet may help explain why nations in the Mediterranean region have historically had lower rates of heart disease and some cancers, including breast cancer, compared with other European countries and the U.S.

Until now, only two other studies have looked at the relationship between Mediterranean-style eating and the risk of breast cancer, both done in the U.S. Each found a connection between the diet and lower breast cancer risk, although in one the link was limited to breast cancers that lack receptors for the hormone estrogen — which account for about one-quarter of breast tumors.

The current study focused on women in Greece, as it is the “cradle” of the Mediterranean diet, and a large segment of the population still adheres to it, Dr. Dimitrios Trichopoulos, the senior researcher on the work, told Reuters Health by email.

At the outset, the study participants completed detailed dietary questionnaires and gave information on their lifestyle habits and demographics. Each woman was given a Mediterranean diet score, ranging from 0 to 9, based on how often they consumed vegetables, legumes, fruit and nuts, whole grains, fish and olive oil or other sources of monounsaturated fats; they also won points by limiting meat and dairy.

Of the 14,800 women included, 240 were diagnosed with breast cancer over an average follow-up of 10 years.

Overall, postmenopausal women whose Mediterranean diet scores were in the 6-to-9 range were 22 percent less likely to develop breast cancer than their counterparts with scores between 0 and 3. That was with factors such as age, education, smoking history, weight and exercise habits taken into account.

The findings show an association between Mediterranean eating and lower breast cancer risk, but do not prove cause-and-effect, according to Trichopoulos, who is with the Harvard School of Public Health in Boston and the Bureau of Epidemiologic Research at the Academy of Athens in Greece.

Further studies are needed to confirm the results, he said.

However, other evidence suggests ways the Mediterranean diet might curb cancer risk.

Research has found, for instance, that women who closely follow the diet tend to have lower levels of estrogen, which fuels the growth of the majority of breast cancers, than other women do. Other studies in the lab suggest that the fats found in the Mediterranean diet — both olive oil and the omega-3 fats in oily fish — may slow the growth of cancer cells.

The diet is also typically rich in antioxidants, which protect body cells from damage that can eventually lead to disease, including cancer. Trichopoulos said that if the Mediterranean diet does have a protective effect against cancer, it is “likely” to involve that antioxidant component.

It also makes sense, said the researcher, that the diet could affect the risk of postmenopausal, but not premenopausal, breast cancer.

Younger women who develop breast cancer, he explained, often have a genetic vulnerability to the disease, whereas in older women, lifestyle and environmental exposures may be relatively more important contributors to risk.

Based on their findings, Trichopoulos and his colleagues write, the association between the Mediterranean diet and breast cancer is of “modest, but not negligible, strength.”

In the U.S., a woman's chance of being diagnosed with breast cancer rises from about a half a percent, or one in 233, during her 30s, to about four percent, or one in 27, during her 60s.

Established risk factors for breast cancer include older age and having had a first-degree relative diagnosed with the disease. Research has also linked obesity, sedentary lifestyle, use of hormone replacement therapy and high alcohol intake to an increased risk.

SOURCE: Journal of Clinical Nutrition

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