A study conducted by Children's Hospital & Research Center Oakland scientists identifies a new class of therapeutic agents found naturally in soy that can prevent and possibly treat colon cancer, the third most deadly form of cancer. Sphingadienes (SDs) are natural lipid molecules found in soy that research shows may be the key to fighting colon cancer.
The study, led by Julie Saba, MD, PhD, senior scientist and director of the Cancer Center at Children's Hospital Oakland Research Institute (CHORI), will be featured in the December 15, 2009 issue of Cancer Research. Soy has long been touted as protective against colon cancer, but Dr. Saba's team made the groundbreaking discovery that SDs naturally found in soy may underlie the benefits of soy products.
Dr. Saba and her team first identified SDs in the fruit fly, an organism that is sometimes used to study the genetics of human diseases. Further investigation indicated that elevated SDs actually induced the death of mutant cells in the fly, revealing SDs to be cytotoxic compounds (toxic to cells). Preventative colon cancer strategies often focus on cell death—a normal process the body uses to remove unhealthy or mutant cells, like cancer cells. Coupling this discovery with the finding that soy is a rich source of SDs, researchers made an innovative connection.
"It's very exciting," said Dr. Saba. "First, we are encouraged to find a natural molecule that could be consumed through soy products as a strategy to help prevent colon cancer. Second, this information is important because we can build on our understanding of the structure and metabolism of SDs in terms of developing new drugs to treat people who already have colon cancer. Uncovering how SDs exert their effects also helps us to find the most likely combinations of drugs that may work synergistically to eliminate cancer cells and mutant cells that could give rise to cancer."
Future research is needed to identify the best way to deliver SDs and to confirm the overall toxicity when the compounds are used for extended time periods and in combination with other agents. Dr. Saba, who has already received two grants to continue her research, also hopes to determine if SDs are effective in protection against other cancers.
Dr. Saba also acknowledges that future research is needed to determine if there are other components of soy that are beneficial in fighting colon cancer. In the meantime, Dr. Saba says, "I would be comfortable recommending soy products as a change in the diet that could protect against cancer. The more that soy is studied, the more of these protective agents are found, so it's a very healthy diet choice."
Tuesday, November 24, 2009
Monday, November 23, 2009
Exercise Fights Strokes
Moderate-to-heavy exercise may reduce risk of stroke for men
Men who regularly take part in moderate-to-heavy intensity exercise such as jogging, tennis or swimming may be less likely to have a stroke than people who get no exercise or only light exercise, such as walking, golfing, or bowling, according to a study published in the November 24, 2009, print issue of Neurology®, the medical journal of the American Academy of Neurology.
However, exercise did not have a protective effect against stroke for women. Women who took part in moderate-to-heavy intensity exercise did not have a reduced risk of stroke.
The study involved 3,298 people living in northern Manhattan, NY, with an average age of 69 who were followed for about nine years. During that time, there were 238 strokes. A total of 41 percent of the participants reported that they participated in no physical activity. Twenty percent regularly participated in moderate-to-heavy intensity activities.
Men who participated in moderate-to-heavy intensity activities were 63 percent less likely to have a stroke than people with no physical activity. The baseline risk of ischemic stroke over five years in the entire group was 4.3 percent; among those with moderate-to-heavy intensity activities the risk was 2.7 percent, and among those with no activity it was 4.6 percent.
"Taking part in moderate-to-heavy intensity physical activity may be an important factor in preventing stroke," said study author Joshua Z. Willey, MD, of Columbia University Medical Center and New York Presbyterian Hospital at Columbia. Willey is also a member of the American Academy of Neurology. "A large percentage of the participants were not taking part in any physical activities. This may be true of many elderly people who live in cities. Identifying ways to improve physical activity among these people may be a key goal for public health."
These results are contrary to some other studies that found that even light intensity physical activity reduced the risk of stroke. Willey said the number of participants may not have been large enough to detect subtle differences in the group that took part in only light physical activity.
Stroke is the leading cause of disability and the third-leading cause of death in the United States.
Men who regularly take part in moderate-to-heavy intensity exercise such as jogging, tennis or swimming may be less likely to have a stroke than people who get no exercise or only light exercise, such as walking, golfing, or bowling, according to a study published in the November 24, 2009, print issue of Neurology®, the medical journal of the American Academy of Neurology.
However, exercise did not have a protective effect against stroke for women. Women who took part in moderate-to-heavy intensity exercise did not have a reduced risk of stroke.
The study involved 3,298 people living in northern Manhattan, NY, with an average age of 69 who were followed for about nine years. During that time, there were 238 strokes. A total of 41 percent of the participants reported that they participated in no physical activity. Twenty percent regularly participated in moderate-to-heavy intensity activities.
Men who participated in moderate-to-heavy intensity activities were 63 percent less likely to have a stroke than people with no physical activity. The baseline risk of ischemic stroke over five years in the entire group was 4.3 percent; among those with moderate-to-heavy intensity activities the risk was 2.7 percent, and among those with no activity it was 4.6 percent.
"Taking part in moderate-to-heavy intensity physical activity may be an important factor in preventing stroke," said study author Joshua Z. Willey, MD, of Columbia University Medical Center and New York Presbyterian Hospital at Columbia. Willey is also a member of the American Academy of Neurology. "A large percentage of the participants were not taking part in any physical activities. This may be true of many elderly people who live in cities. Identifying ways to improve physical activity among these people may be a key goal for public health."
These results are contrary to some other studies that found that even light intensity physical activity reduced the risk of stroke. Willey said the number of participants may not have been large enough to detect subtle differences in the group that took part in only light physical activity.
Stroke is the leading cause of disability and the third-leading cause of death in the United States.
Flaxseed oil and osteoporosis
Animal studies suggest that adding flaxseed oil to the diet could reduce the risk of osteoporosis in post-menopausal women and women with diabetes, according to a report to be published in the International Journal of Food Safety, Nutrition and Public Health.
Mer Harvi and colleagues at the National Research Center, in Cairo, Egypt, have studied the effect of diabetes on bone health and evaluated how flaxseed oil in the diet might delay the onset of osteoporosis. The researchers studied 70 female albino rats of which 30 had their ovaries removed (ovx) to simulate the post-menopausal state and experimental diabetes was present in one group of rodents.
The researchers then classified the rats as control, sham, diabetic, diabetic received flaxseed oil in the diet, ovx, ovx-diabetic and ovx-diabetic received flaxseed oil in the diet.
After two months, the team collected urine and blood samples from the rats and measured serum insulin-like growth factor 1 (IGF-1) and the bone-creating protein osteocalcin. They found that these two compounds were present at higher levels in the ovx and the diabetic ovx groups, but much lower in the non-ovx diabetic group. The concentrations of IGF-1 and osteocalcin could be raised to normal levels by adding flaxseed oil to the diet.
The team also found that the levels of deoxypyridinoline in the urine were raised in the diabetic group. Deoxypyridinoline is normally present in healthy bone and its presence in urine is a specific marker for bone resorption associated with osteoporosis. Levels of this marker compound fell when the rats were given flaxseed oil.
The team concludes that diabetes has a more pronounced effect on bone health than ovariectomy and so may suggest that diabetes in post-menopausal women may also be a greater risk factor for osteoporosis than the decline in sex hormones associated with the menopause. However, their results suggest that flaxseed oil has a beneficial effect on bone mineral density and reduces markers associated with osteoporosis, suggesting that this dietary supplement could be beneficial to women with diabetes in reducing their risk of osteoporosis.
The team explains that the presence of so-called "n-3 fatty acids" in flaxseed oil may play a role in protecting the processes of matrix formation and bone mineralization, which are apparently compromised by diabetes and the menopause. "We recommend further investigations using animals and humans to confirm the effect of using dietary flaxseed oil to improve bone health and to prevent osteoporosis," Harvi and colleagues conclude.
Mer Harvi and colleagues at the National Research Center, in Cairo, Egypt, have studied the effect of diabetes on bone health and evaluated how flaxseed oil in the diet might delay the onset of osteoporosis. The researchers studied 70 female albino rats of which 30 had their ovaries removed (ovx) to simulate the post-menopausal state and experimental diabetes was present in one group of rodents.
The researchers then classified the rats as control, sham, diabetic, diabetic received flaxseed oil in the diet, ovx, ovx-diabetic and ovx-diabetic received flaxseed oil in the diet.
After two months, the team collected urine and blood samples from the rats and measured serum insulin-like growth factor 1 (IGF-1) and the bone-creating protein osteocalcin. They found that these two compounds were present at higher levels in the ovx and the diabetic ovx groups, but much lower in the non-ovx diabetic group. The concentrations of IGF-1 and osteocalcin could be raised to normal levels by adding flaxseed oil to the diet.
The team also found that the levels of deoxypyridinoline in the urine were raised in the diabetic group. Deoxypyridinoline is normally present in healthy bone and its presence in urine is a specific marker for bone resorption associated with osteoporosis. Levels of this marker compound fell when the rats were given flaxseed oil.
The team concludes that diabetes has a more pronounced effect on bone health than ovariectomy and so may suggest that diabetes in post-menopausal women may also be a greater risk factor for osteoporosis than the decline in sex hormones associated with the menopause. However, their results suggest that flaxseed oil has a beneficial effect on bone mineral density and reduces markers associated with osteoporosis, suggesting that this dietary supplement could be beneficial to women with diabetes in reducing their risk of osteoporosis.
The team explains that the presence of so-called "n-3 fatty acids" in flaxseed oil may play a role in protecting the processes of matrix formation and bone mineralization, which are apparently compromised by diabetes and the menopause. "We recommend further investigations using animals and humans to confirm the effect of using dietary flaxseed oil to improve bone health and to prevent osteoporosis," Harvi and colleagues conclude.
Vitamin D Summary
A string of recent discoveries about the multiple health benefits of vitamin D has renewed interest in this multi-purpose nutrient, increased awareness of the huge numbers of people who are deficient in it, spurred research and even led to an appreciation of it as "nature's antibiotic."
On issues ranging from the health of your immune system to prevention of heart disease and even vulnerability to influenza, vitamin D is now seen as one of the most critical nutrients for overall health. But it's also one of those most likely to be deficient – especially during winter when production of the "sunshine vitamin" almost grinds to a halt for millions of people in the United States, Europe and other northern temperate zones.
Analogs of the vitamin are even being considered for use as new therapies against tuberculosis, AIDS, and other concerns. And federal experts are considering an increase in the recommended daily intake of the vitamin as more evidence of its value emerges, especially for the elderly.
"About 70 percent of the population of the United States has insufficient levels of vitamin D," said Adrian Gombart, a principal investigator with the Linus Pauling Institute at Oregon State University. "This is a critical issue as we learn more about the many roles it may play in fighting infection, balancing your immune response, helping to address autoimmune problems, and even preventing heart disease."
Those issues were just outlined in a new publication in Future Microbiology, a professional journal, on the latest findings on vitamin D research, at OSU and in many other programs around the world.
Of particular interest are findings made recently by OSU scientists that vitamin D induces the "expression" of cathelicidin, an antimicrobial peptide gene. This explains in part how it helps serve as the first line of defense in your immune response against minor wounds, cuts, and both bacterial and viral infections. Experts believe advances in the use of cathelicidin may form the basis for new therapies.
Once believed to be related primarily to bone health and rickets – a disease caused by chronic deficiency of vitamin D – it's now understood that optimal levels of this nutrient influence much more than that.
"Vitamin D insufficiency and deficiency is a world-wide, public health problem in both developed and developing nations," the new report concluded. "Nearly one billion people world-wide are deficient."
Vitamin D can be obtained from the diet, often through supplemented foods such as milk, but those sources are rarely adequate, experts say. Most people get the bulk of this fat-soluble vitamin from the UV-B radiation in sun exposure, which naturally causes the skin to produce it. However, people with dark skin, infants and almost anyone living north of about 40 degrees latitude – which is a huge portion of the U.S. population and most of Europe– are often deficient after months of inadequate winter sunshine.
Among the values and observations about vitamin D that are outlined in the new report:
• Low levels of circulating vitamin D are associated with increased risk and mortality from cancer.
• Vitamin D plays an important role in activating the immune system, fostering the "innate" immune response and controlling over-reaction of adaptive immunity, and as such may help control autoimmune diseases such as multiple sclerosis, psoriasis and rheumatoid arthritis.
• Cathelicidin can profoundly boost the innate immune system, and could form the basis for new therapies to combat pathogenic infections.
• The regulation of cathelicidin by vitamin D, a unique biological pathway for the function of vitamin D that could help explain its multiple roles in proper immune function, is so important that it's only known to exist in two groups of animals - humans and non-human primates - and has been conserved in them through millions of years of evolution.
• Vitamin D deficiency is a risk factor for tuberculosis, was historically used to treat it, and analogs of it may provide the basis for new therapeutic approaches not only to that disease but also HIV infection.
• Epidemiological studies show a link between vitamin D deficiency and increased rates of respiratory infection and influenza, and it has been hypothesized that flu epidemics may be the result of vitamin D deficiency.
• Higher levels of a protein linked to vitamin D have been associated with reduced infections and longer survival of dialysis patients.
• Vitamin D has important roles in reducing inflammation, blood pressure and helping to protect against heart disease.
There is still much to explore about the mechanisms of action of vitamin D, the potential use of synthetic analogs of it in new therapies, and its role in fighting infection, Gombart said. Since only primates and humans have the same biological pathways for use of vitamin D to regulate cathelicidin, studies have been constrained by the lack of appropriate animal models for research, he said. OSU scientists hope to address that by creation of a line of genetically modified mice that have some of these characteristics.
One compelling new study just done by researchers at the Intermountain Medical Center in Utah, and presented at a meeting of the American Heart Association, followed for more than a year nearly 28,000 patients ages 50 or older with no prior history of cardiovascular disease. It found that in patients with very low levels of vitamin D – compared to those with normal levels – 77 percent were more likely to die, 45 percent were more likely to develop coronary artery disease, and 78 percent were more likely to have a stroke.
On issues ranging from the health of your immune system to prevention of heart disease and even vulnerability to influenza, vitamin D is now seen as one of the most critical nutrients for overall health. But it's also one of those most likely to be deficient – especially during winter when production of the "sunshine vitamin" almost grinds to a halt for millions of people in the United States, Europe and other northern temperate zones.
Analogs of the vitamin are even being considered for use as new therapies against tuberculosis, AIDS, and other concerns. And federal experts are considering an increase in the recommended daily intake of the vitamin as more evidence of its value emerges, especially for the elderly.
"About 70 percent of the population of the United States has insufficient levels of vitamin D," said Adrian Gombart, a principal investigator with the Linus Pauling Institute at Oregon State University. "This is a critical issue as we learn more about the many roles it may play in fighting infection, balancing your immune response, helping to address autoimmune problems, and even preventing heart disease."
Those issues were just outlined in a new publication in Future Microbiology, a professional journal, on the latest findings on vitamin D research, at OSU and in many other programs around the world.
Of particular interest are findings made recently by OSU scientists that vitamin D induces the "expression" of cathelicidin, an antimicrobial peptide gene. This explains in part how it helps serve as the first line of defense in your immune response against minor wounds, cuts, and both bacterial and viral infections. Experts believe advances in the use of cathelicidin may form the basis for new therapies.
Once believed to be related primarily to bone health and rickets – a disease caused by chronic deficiency of vitamin D – it's now understood that optimal levels of this nutrient influence much more than that.
"Vitamin D insufficiency and deficiency is a world-wide, public health problem in both developed and developing nations," the new report concluded. "Nearly one billion people world-wide are deficient."
Vitamin D can be obtained from the diet, often through supplemented foods such as milk, but those sources are rarely adequate, experts say. Most people get the bulk of this fat-soluble vitamin from the UV-B radiation in sun exposure, which naturally causes the skin to produce it. However, people with dark skin, infants and almost anyone living north of about 40 degrees latitude – which is a huge portion of the U.S. population and most of Europe– are often deficient after months of inadequate winter sunshine.
Among the values and observations about vitamin D that are outlined in the new report:
• Low levels of circulating vitamin D are associated with increased risk and mortality from cancer.
• Vitamin D plays an important role in activating the immune system, fostering the "innate" immune response and controlling over-reaction of adaptive immunity, and as such may help control autoimmune diseases such as multiple sclerosis, psoriasis and rheumatoid arthritis.
• Cathelicidin can profoundly boost the innate immune system, and could form the basis for new therapies to combat pathogenic infections.
• The regulation of cathelicidin by vitamin D, a unique biological pathway for the function of vitamin D that could help explain its multiple roles in proper immune function, is so important that it's only known to exist in two groups of animals - humans and non-human primates - and has been conserved in them through millions of years of evolution.
• Vitamin D deficiency is a risk factor for tuberculosis, was historically used to treat it, and analogs of it may provide the basis for new therapeutic approaches not only to that disease but also HIV infection.
• Epidemiological studies show a link between vitamin D deficiency and increased rates of respiratory infection and influenza, and it has been hypothesized that flu epidemics may be the result of vitamin D deficiency.
• Higher levels of a protein linked to vitamin D have been associated with reduced infections and longer survival of dialysis patients.
• Vitamin D has important roles in reducing inflammation, blood pressure and helping to protect against heart disease.
There is still much to explore about the mechanisms of action of vitamin D, the potential use of synthetic analogs of it in new therapies, and its role in fighting infection, Gombart said. Since only primates and humans have the same biological pathways for use of vitamin D to regulate cathelicidin, studies have been constrained by the lack of appropriate animal models for research, he said. OSU scientists hope to address that by creation of a line of genetically modified mice that have some of these characteristics.
One compelling new study just done by researchers at the Intermountain Medical Center in Utah, and presented at a meeting of the American Heart Association, followed for more than a year nearly 28,000 patients ages 50 or older with no prior history of cardiovascular disease. It found that in patients with very low levels of vitamin D – compared to those with normal levels – 77 percent were more likely to die, 45 percent were more likely to develop coronary artery disease, and 78 percent were more likely to have a stroke.
Thursday, November 19, 2009
Beneficial Effects of Aspirin in Cardiovascular Disease
On November 15, 2009, Florida Atlantic University (FAU) researcher Charles H. Hennekens, M.D., the first Sir Richard Doll Research Professor in the Charles E. Schmidt College of Biomedical Science will present at the American Heart Association's Annual Scientific Sessions meeting in Orlando, FL, the first data in humans to show that all doses of aspirin used in clinical practice increase nitric oxide. Nitric oxide is released from the blood vessel wall and may decrease the development and progression of plaques leading to heart attacks and strokes.
Hennekens was the first to demonstrate that aspirin can prevent a first heart attack or a first stroke.
The abstract, titled "Usual Doses of Aspirin Increase Nitric Acid Formation in Humans" is published in the November 2009 issue of Circulation, the official journal of the American Heart Association.
FAU researchers conducted a randomized trial in patients at high risk of a first heart attack or stroke and assigned them to different doses of aspirin for 12 weeks. All doses produced highly significant beneficial effects on two important and well documented markers of nitric oxide formation.
"While the ability of aspirin to decrease the clumping of blood platelets is sufficient to explain why the drug decreases heart attacks and strokes, these data suggest a new and novel mechanism," said Hennekens.
Co-author and project director of the trial and affiliate clinical instructor of clinical science and medical education, Wendy Schneider, MSN, RN, said, "We are proposing new and longer term research to test whether this hypothesis has clinical or public health relevance."
The American Heart Association recommends aspirin use for patients who've had a myocardial infarction (heart attack), unstable angina, ischemic stroke (caused by blood clot) or transient ischemic attacks (TIAs or "little strokes"), if not contraindicated. This recommendation is based on sound evidence from clinical trials showing that aspirin helps prevent the recurrence of such events as heart attack, hospitalization for recurrent angina, second strokes, etc. (secondary prevention). Studies show aspirin also helps prevent these events from occurring in people at high risk (primary prevention).
Hennekens was the first to demonstrate that aspirin can prevent a first heart attack or a first stroke.
The abstract, titled "Usual Doses of Aspirin Increase Nitric Acid Formation in Humans" is published in the November 2009 issue of Circulation, the official journal of the American Heart Association.
FAU researchers conducted a randomized trial in patients at high risk of a first heart attack or stroke and assigned them to different doses of aspirin for 12 weeks. All doses produced highly significant beneficial effects on two important and well documented markers of nitric oxide formation.
"While the ability of aspirin to decrease the clumping of blood platelets is sufficient to explain why the drug decreases heart attacks and strokes, these data suggest a new and novel mechanism," said Hennekens.
Co-author and project director of the trial and affiliate clinical instructor of clinical science and medical education, Wendy Schneider, MSN, RN, said, "We are proposing new and longer term research to test whether this hypothesis has clinical or public health relevance."
The American Heart Association recommends aspirin use for patients who've had a myocardial infarction (heart attack), unstable angina, ischemic stroke (caused by blood clot) or transient ischemic attacks (TIAs or "little strokes"), if not contraindicated. This recommendation is based on sound evidence from clinical trials showing that aspirin helps prevent the recurrence of such events as heart attack, hospitalization for recurrent angina, second strokes, etc. (secondary prevention). Studies show aspirin also helps prevent these events from occurring in people at high risk (primary prevention).
Wednesday, November 18, 2009
Green tea may protect liver cells
Green tea may protect liver cells and reduce the deposition of collagen fibers in the liver. Green tea provides a safe and effective strategy for improving hepatic fibrosis.
Several studies have shown that lipid peroxidation stimulates collagen production in fibroblasts and hepatic stellate cells (HSC), and plays an important role in the development of liver fibrosis. Hepatoprotective effects of green tea against carbon tetrachloride, cholestasis and alcohol induced liver fibrosis were reported in many studies. However, the hepatoprotective effect of green tea in dimethylnitrosamine (DMN)-induced models has not been studied.
A research article published on November 7, 2009 in the World Journal of Gastroenterology addresses this question. The research team, led by Prof. Hong-Yon Cho from Korea University examined the protective effect of green tea extract (GT) on hepatic fibrosis in a rat HSC line and in a rat model of DMN-induced hepatic fibrosis.
The results showed GT administration prevented the development of hepatic fibrosis in the rat model of DMN-induced liver fibrosis. These results were confirmed both by liver histology and by quantitative measurement of hepatic hydroxyproline content, a marker of liver collagen deposition. Accordingly, inhibition of proliferation, reduced collagen deposition, and type 1 collagen expression were observed in activated HSC-T6 cells following GT treatment. These results imply that GT reduced the proliferation of activated HSC and down regulated the collagen content and expression of collagen type 1, thereby ameliorating hepatic fibrosis.
The researchers drew a conclusion that
Several studies have shown that lipid peroxidation stimulates collagen production in fibroblasts and hepatic stellate cells (HSC), and plays an important role in the development of liver fibrosis. Hepatoprotective effects of green tea against carbon tetrachloride, cholestasis and alcohol induced liver fibrosis were reported in many studies. However, the hepatoprotective effect of green tea in dimethylnitrosamine (DMN)-induced models has not been studied.
A research article published on November 7, 2009 in the World Journal of Gastroenterology addresses this question. The research team, led by Prof. Hong-Yon Cho from Korea University examined the protective effect of green tea extract (GT) on hepatic fibrosis in a rat HSC line and in a rat model of DMN-induced hepatic fibrosis.
The results showed GT administration prevented the development of hepatic fibrosis in the rat model of DMN-induced liver fibrosis. These results were confirmed both by liver histology and by quantitative measurement of hepatic hydroxyproline content, a marker of liver collagen deposition. Accordingly, inhibition of proliferation, reduced collagen deposition, and type 1 collagen expression were observed in activated HSC-T6 cells following GT treatment. These results imply that GT reduced the proliferation of activated HSC and down regulated the collagen content and expression of collagen type 1, thereby ameliorating hepatic fibrosis.
The researchers drew a conclusion that
Tuesday, November 17, 2009
How fish is cooked affects heart-health benefits of omega-3 fatty acids
If you eat fish to gain the heart-health benefits of its omega-3 fatty acids, baked or boiled fish is better than fried, salted or dried, according to research presented at the American Heart Association’s Scientific Sessions 2009.
And, researchers said, adding low-sodium soy sauce or tofu will enhance the benefits.
“It appears that boiling or baking fish with low-sodium soy sauce (shoyu) and tofu is beneficial, while eating fried, salted or dried fish is not,” said Lixin Meng, M.S., lead researcher of the study and Ph.D. candidate at the University of Hawaii at Manoa. “In fact, these methods of preparation may contribute to your risk. We did not directly compare boiled or baked fish vs. fried fish, but one can tell from the (risk) ratios, boiled or baked fish is in the protective direction but not fried fish.”
The findings also suggest that the cardioprotective benefits vary by gender and ethnicity — perhaps because of the preparation methods, genetic susceptibility or hormonal factors.
Many studies have suggested that eating omega-3 fatty acids reduces the risk of heart disease; however, little is known about which source is most beneficial.
In this study, researchers examined the source, type, amount and frequency of dietary omega-3 ingestion among gender and ethnic groups. Participants were part of the Multiethnic Cohort living in Hawaii and Los Angeles County when they were recruited between 1993 and 1996. The group consisted of 82,243 men and 103,884 women of African-American, Caucasian, Japanese, Native Hawaiian and Latino descent ages 45 to 75 years old with no history of heart disease.
Researchers divided their intake of canned tuna, other canned fish, fish excluding shell fish, or soy products that contain plant omega-3s (soy, tofu and shoyu) into quintiles, quartiles, or tertiles when applicable. They also surveyed the preparation methods: raw, baked, boiled; fried; salted or dried. The initial study did not consider grilled fish.
Those in the highest quintile consumed a median 3.3 grams of omega-3 fatty acids a day. The lowest quintile consumed a median of 0.8 grams a day.
Omega-3 intake was inversely associated with overall risk of death due to heart disease in men — a trend mainly observed in Caucasians, Japanese Americans and Latinos. However, there weren’t many blacks or Hawaiians in the study, so the results should be interpreted cautiously, Meng said.
Overall, men who ate about 3.3 grams per day of omega-3 fatty acids had a 23 percent lower risk of cardiac death compared to those who ate 0.8 grams daily.
“Clearly, we are seeing that the higher the dietary omega-3 intake, the lower the risk of dying from heart disease among men,” Meng said.
Japanese and Hawaiians eat fish more often compared to whites, blacks and Latinos, and they prepare fish in a variety of methods, Meng noted.
For women, the omega-3 effect was cardioprotective at each level of consumption but not consistently significant, Meng said. Salted and dried fish was a risk factor in women.
In contrast, adding less than 1.1 gram/day shoyu and teriyaki sauce at the dinner table was protective for men but not for greater than 1.1 gram/day. For women, shoyu use showed a clear inverse relationship to death from heart disease. She noted that shoyu that is high in sodium can raise blood pressure, so she stressed low-sodium products. Eating tofu also had a cardioprotective effect in all ethnic groups.
“My guess is that, for women, eating omega-3s from shoyu and tofu that contain other active ingredients such as phytoestrogens, might have a stronger cardioprotective effect than eating just omega-3s,” said Meng, noting that further studies are needed to confirm the hypothesis.
During the average 11.9 years of follow-up, 4,516 heart-related deaths occurred in the group, according to state and national death records, which were cross-referenced through the end of 2005.
The study didn’t consider possible dietary changes over time; subjects who were diagnosed with heart disease after their baseline food intake surveys might have modified their eating habits. Further, the study didn’t account for the possible effects of fish-oil supplementation.
In light of these limitations, the researchers plan to include subjects’ dietary patterns over time and a cross-validation of their omega-3 levels through blood analysis.
“Our findings can help educate people on how much fish to eat and how to cook it to prevent heart disease,” Meng said. “Alternately, if it is verified that the interactions between fish consumption, risk factors and ethnicity are due to genetic susceptibility, the heart-disease prevention message can be personalized to ethnic groups, and future study could identify susceptibility at the genetic level.”
The American Heart Association recommends eating fish (particularly fatty fish) at least two times a week and eating tofu and other forms of soybeans, canola, walnut and flaxseed, and their oils. Learn specific information on the recommendations.
And, researchers said, adding low-sodium soy sauce or tofu will enhance the benefits.
“It appears that boiling or baking fish with low-sodium soy sauce (shoyu) and tofu is beneficial, while eating fried, salted or dried fish is not,” said Lixin Meng, M.S., lead researcher of the study and Ph.D. candidate at the University of Hawaii at Manoa. “In fact, these methods of preparation may contribute to your risk. We did not directly compare boiled or baked fish vs. fried fish, but one can tell from the (risk) ratios, boiled or baked fish is in the protective direction but not fried fish.”
The findings also suggest that the cardioprotective benefits vary by gender and ethnicity — perhaps because of the preparation methods, genetic susceptibility or hormonal factors.
Many studies have suggested that eating omega-3 fatty acids reduces the risk of heart disease; however, little is known about which source is most beneficial.
In this study, researchers examined the source, type, amount and frequency of dietary omega-3 ingestion among gender and ethnic groups. Participants were part of the Multiethnic Cohort living in Hawaii and Los Angeles County when they were recruited between 1993 and 1996. The group consisted of 82,243 men and 103,884 women of African-American, Caucasian, Japanese, Native Hawaiian and Latino descent ages 45 to 75 years old with no history of heart disease.
Researchers divided their intake of canned tuna, other canned fish, fish excluding shell fish, or soy products that contain plant omega-3s (soy, tofu and shoyu) into quintiles, quartiles, or tertiles when applicable. They also surveyed the preparation methods: raw, baked, boiled; fried; salted or dried. The initial study did not consider grilled fish.
Those in the highest quintile consumed a median 3.3 grams of omega-3 fatty acids a day. The lowest quintile consumed a median of 0.8 grams a day.
Omega-3 intake was inversely associated with overall risk of death due to heart disease in men — a trend mainly observed in Caucasians, Japanese Americans and Latinos. However, there weren’t many blacks or Hawaiians in the study, so the results should be interpreted cautiously, Meng said.
Overall, men who ate about 3.3 grams per day of omega-3 fatty acids had a 23 percent lower risk of cardiac death compared to those who ate 0.8 grams daily.
“Clearly, we are seeing that the higher the dietary omega-3 intake, the lower the risk of dying from heart disease among men,” Meng said.
Japanese and Hawaiians eat fish more often compared to whites, blacks and Latinos, and they prepare fish in a variety of methods, Meng noted.
For women, the omega-3 effect was cardioprotective at each level of consumption but not consistently significant, Meng said. Salted and dried fish was a risk factor in women.
In contrast, adding less than 1.1 gram/day shoyu and teriyaki sauce at the dinner table was protective for men but not for greater than 1.1 gram/day. For women, shoyu use showed a clear inverse relationship to death from heart disease. She noted that shoyu that is high in sodium can raise blood pressure, so she stressed low-sodium products. Eating tofu also had a cardioprotective effect in all ethnic groups.
“My guess is that, for women, eating omega-3s from shoyu and tofu that contain other active ingredients such as phytoestrogens, might have a stronger cardioprotective effect than eating just omega-3s,” said Meng, noting that further studies are needed to confirm the hypothesis.
During the average 11.9 years of follow-up, 4,516 heart-related deaths occurred in the group, according to state and national death records, which were cross-referenced through the end of 2005.
The study didn’t consider possible dietary changes over time; subjects who were diagnosed with heart disease after their baseline food intake surveys might have modified their eating habits. Further, the study didn’t account for the possible effects of fish-oil supplementation.
In light of these limitations, the researchers plan to include subjects’ dietary patterns over time and a cross-validation of their omega-3 levels through blood analysis.
“Our findings can help educate people on how much fish to eat and how to cook it to prevent heart disease,” Meng said. “Alternately, if it is verified that the interactions between fish consumption, risk factors and ethnicity are due to genetic susceptibility, the heart-disease prevention message can be personalized to ethnic groups, and future study could identify susceptibility at the genetic level.”
The American Heart Association recommends eating fish (particularly fatty fish) at least two times a week and eating tofu and other forms of soybeans, canola, walnut and flaxseed, and their oils. Learn specific information on the recommendations.
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