The EPA and FDA would have expectant mothers reduce or eliminate their intake of seafood due to the possibility that the small amount of methyl mercury contained in some fish might adversely affect their unborn offspring.  However, studies have shown that the benefits of eating seafood far outweigh the risks, for all age groups and both sexes.  Can the same be said of mercury amalgam restorations (see Development)?

If not, why aren't the EPA and FDA clamoring for the elimination of mercury amalgam restorations at least in pregnant women, women of child bearing age, and children?  Despite their assertions, a panel of experts convened by the World Health Organization in 1991, determined that mercury amalgam fillings were the primary source of mercury exposure in the non-occupationally exposed population and NOT SEAFOOD!! (see Mercury Exposure)

In other words the FDA and EPA would have us believe that consuming fish that MIGHT contain a small amount of mercury should be avoided despite its many health benefits but having a dentist put in a mercury amalgam filling that DEFINITELY contains mercury, some as much as 500 mg, 5 cm from a child's brain is somehow OK.  

TABLE OF CONTENTS

Association between prenatal exposure to methylmercury and developmental outcomes in Seychellois children: effect modification by social and environmental factors.

Neurotoxicology 1999 Oct;20(5):833-41

http://www.ncbi.nlm.nih.gov:80/entrez/queryPubMed&list_uids=10591519&dopt=Abstract

Davidson PW, Myer GJ, Shamlaye C, Cox C, Gao P, Axtell C, Morris D, Sloane-Reeves J, Cernichiari E, Choi A, Palumbo D, Clarkson TW.

Department of Pediatrics, University of Rochester School of Medicine and Dentistry, New York 14642, USA. phil_davidson@urmc.rochester.edu

The Seychelles Child Development Study (SCDS) is testing the hypothesis that prenatal exposure to low doses of MeHg from maternal consumption of fish is associated with the child's developmental outcomes. No deleterious relationships between exposure to MeHg and cognitive functions have been identified in the primary analysis of the main cohort through 66 months of age. We performed secondary analyses to determine if effect modification (EM) from social and environmental factors was affecting associations between MeHg and outcomes.

METHODS: MeHg exposure was determined by analysis of maternal hair growing during pregnancy. Children in our Main Study cohort were evaluated at 6.5 months (N = 740) for visual recognition memory and visual attention using the Fagan Infantest, at 19 months (N = 738) and 29 months (N = 736) with the Bayley Scales of Infant Development (BSID). Interactions between MeHg and Caregiver Intelligence, Family Income and Home Environment were examined by multiple regression analysis. RESULTS: The median prenatal MeHg exposure was 5.9 ppm (Range 0.5-26.7 ppm). No EM occurred for preferential looking or visual attention at 6.5 months, for  the BSID Psychomotor Scale at either 19 or 29 months, or for activity level at 29 months as measured by the BSID Infant Behavior Record. Interactions between MeHg level and both caregiver intelligence and family income were statistically significant for the BSID Mental Scale at 19 months but not at 29 months. These showed enhancement of MDI scores with increasing maternal MeHg in higher caregiver IQ groups at several levels of family income.

CONCLUSIONS: In Seychellois children, consistent major EM by social or environmental factors were not identified. The small EM by caregiver intelligence and social factors at 19 months is consistent with the enhanced performance we reported when this cohort was examined at 66 months. 

Eat Fish for Healthy Pregnancy

http://health.discovery.com/news/reu/20020218/eatfish.html

http://bmj.com/cgi/content/full/324/7335/447

02/22/202 — LONDON (Reuters) - Eating fish can improve a woman's chances of having a full-term pregnancy and a healthy, bouncy baby, Danish researchers said on Friday.

They suspect that fish, which is rich in omega-3 fatty acids, can increase the child's birth weight by prolonging the pregnancy and preventing premature births.

He and his colleagues compared the diets of 8,000 Danish women during pregnancy to determine if seafood had an impact on early births.

"Low consumption of fish was a strong risk factor for pre-term delivery and low birth weight," said Sjurour Frooi Olsen, a researcher at the Statens Serum Institute in Copenhagen.

In the study reported in the British Medical Journal, the women were asked how often they ate fish during their pregnancy and whether it was in a hot meal, salad or if they took a fish oil supplement.

The researchers found that women who ate the most fish had fewer premature births and smaller babies than those who did not.

Pre-term deliveries fell from 7.1 percent in women who never ate fish to 1.9 percent in expectant mothers who ate fish at least once a week.

Olsen said his findings agreed with previous studies which found a link between fish consumption and full-term pregnancies.

Oily fish such as salmon, herring and mackerel are rich in omega-3 fatty acids, which have also been found to be effective in fighting depression and in inhibiting the growth of prostate cancer cells.

Mom's fish intake linked to preterm delivery risk

By Amy Norton

From Reuters Health

NEW YORK, Feb 22 (Reuters Health) - A new study links low consumption of fish early in pregnancy to higher odds of preterm delivery and low birth weight--suggesting, researchers say, that the omega-3 fatty acids in fish and fish oil supplements might help prevent these complications.

Together with past research suggesting fish oil may lower the risk of premature delivery, these findings lay the groundwork for clinical trials on the effects of omega-3 fatty acids during pregnancy, researchers conclude in the February 23rd issue of the British Medical Journal.

Their study of more than 8,700 pregnant women in Denmark found that those who said they currently ate no fish were around three times more likely than those who ate the most to have a preterm delivery.

But an expert not involved in the study told Reuters Health that while the findings are "interesting," pregnant women should not take them to mean that eating more fish is necessarily a good thing. Moreover, there are health concerns surrounding high fish consumption--particularly for pregnant women--because some fish can contain significant amounts of metals like lead and mercury, said Dr. David Nagey of Johns Hopkins University in Baltimore, Maryland.

Overall, women who ate some fish were less likely than those who did not to deliver prematurely, and their babies tended to weigh more. For instance, the rate of premature birth among women who ate no fish was about 7%, compared with roughly 2% for women who had fish at least once a week.

But there was no clear "dose-response" relationship between fish intake and the risks of preterm delivery and low birth weight, Nagey pointed out. This means that the risks did not continue to decline as women's fish intake rose. According to Nagey, this suggests other factors could explain the link--or, he noted, there could be a negative effect from eating a lot of fish that counters the benefits of moderate consumption.

Indeed, some fish are considered risky during pregnancy. In the US, the Food and Drug Administration advises pregnant women to avoid eating shark, swordfish, king mackerel and tilefish because they may contain high levels of mercury, which can potentially harm the developing fetal nervous system. Mercury occurs naturally in the environment and as a byproduct of industrial pollution; it can accumulate in certain long-lived fish that consume other fish.

In the current study, Dr. Sjurour Frooi Olsen, of Statens Serum Institut in Copenhagen, and Dr. Niels Jorgen Secher questioned women on their fish intake, as well as smoking and alcohol consumption. They also accounted for factors such as age, weight before pregnancy and education. None of the women were taking fish oil supplements.

According to the researchers, their results suggest that for women who eat little or no fish, small amounts of omega-3 fatty acids--through either fish or fish oil supplements--might help reduce the odds of preterm delivery or low birth weight.

But Nagey said that drawing such conclusions from these findings is "irresponsible."

Olsen, however, told Reuters Health that their study suggests even eating small amounts of fish could be beneficial, so the risks of pollutant contamination would be low. If women have concerns, the researcher noted, they can contact local health authorities for information on pollutant levels in various fish species.

SOURCE: British Medical Journal 2002;324:447-450.

Fish oil may reduce risk of irregular heartbeat

By Charnicia E. Huggins

Source: Circulation 2002;105

http://www.reutershealth.com/archive/2002/04/08/eline/links/20020408elin010.html

NEW YORK, Apr 08 (Reuters Health) - Previous studies have suggested that fish oil supplements may reduce the risk of an additional heart attack or stroke in patients who have recently experienced a heart attack. Now new study findings reveal that the supplement may also reduce the risk of sudden death.

The findings show that this reduced risk was evident after as few as 3 months, which seems to support the hypothesis that adding n-3 polyunsaturated fatty acids (PUFAs)--commonly found in fish and fish oil--to a healthy diet may lower the risk of fatal arrhythmia, an irregular heartbeat that in severe cases can lead to cardiac arrest, the authors report.

"Reduction of sudden death appeared early after start of treatment," lead study author Dr. Roberto Marchioli, of Consorzio Mario Negri Sud in Italy, told Reuters Health. This "seems to support the idea that (the benefits of PUFAs) could be due to an anti-arryhythmia effect," he added.

The study included 11,323 patients who had suffered a heart attack within the previous 3 months. All of the patients received the same preventive care and ate Mediterranean-style diets rich in fruits, vegetables, olive oil and fish. But some patients also consumed 1 gram of the fish oil supplements per day.

During the 3.5-year follow-up period, 1,031 individuals died, Marchioli and his colleagues report in the April issue of the Circulation: Journal of the American Heart Association.

Patients who took the fish oil supplements appeared to be at a 41% lower risk of death from any cause after only 3 months of treatment, study findings indicate.

After 4 months of treatment, these patients also appeared to be at a significantly reduced risk of sudden cardiac death. And by the end of the study period, patients treated with fish oil supplements were 45% less likely to die suddenly from a heart-related cause, Marchioli and his colleagues report.

In light of the findings, Marchioli said that the benefit of fish oil supplements "seems to be additive to the benefit that can be obtained by standard preventive treatment."

"One capsule of a fish oil concentrate daily for 3.5 years resulted in a very significant reduction in sudden cardiac death. Thus, a simple and safe change in diet can potentially produce a large public health benefit," editorialist Dr. Alexander Leaf of Harvard Medical School in Boston, Massachusetts, told Reuters Health.

"Individuals who have known coronary heart disease or a family history of coronary heart disease among immediate relatives would be prudent to heed the recent advice of the American Heart Association to eat two or more meals of oily fish per week or take a daily supplement of fish oil capsules," Leaf added.

SOURCE: Circulation 2002;105.

Blood Levels of Long-Chain n–3 Fatty Acids and the Risk of Sudden Death

Christine M. Albert, M.D., M.P.H., Hannia Campos, Ph.D., Meir J. Stampfer, M.D., Dr.P.H., Paul M. Ridker, M.D., M.P.H., JoAnn E. Manson, M.D., Dr.P.H., Walter C. Willett, M.D., Dr.P.H., and Jing Ma, M.D., Ph.D.

New England Journal of Medicine Volume 346:1113-1118 April 11, 2002 Number 15

http://content.nejm.org/cgi/content/short/346/15/1113

ABSTRACT

Background Experimental data suggest that long-chain n–3 polyunsaturated fatty acids found in fish have antiarrhythmic properties, and a randomized trial suggested that dietary supplements of n–3 fatty acids may reduce the risk of sudden death among survivors of myocardial infarction. Whether long-chain n–3 fatty acids are also associated with the risk of sudden death in those without a history of cardiovascular disease is unknown.

Methods We conducted a prospective, nested case–control analysis among apparently healthy men who were followed for up to 17 years in the Physicians' Health Study. The fatty-acid composition of previously collected blood was analyzed by gas–liquid chromatography for 94 men in whom sudden death occurred as the first manifestation of cardiovascular disease and for 184 controls matched with them for age and smoking status.

Results Base-line blood levels of long-chain n–3 fatty acids were inversely related to the risk of sudden death both before adjustment for potential confounders (P for trend = 0.004) and after such adjustment (P for trend = 0.007). As compared with men whose blood levels of long-chain n–3 fatty acids were in the lowest quartile, the relative risk of sudden death was significantly lower among men with levels in the third quartile (adjusted relative risk, 0.28; 95 percent confidence interval, 0.09 to 0.87) and the fourth quartile (adjusted relative risk, 0.19; 95 percent confidence interval, 0.05 to 0.71).

Conclusions The n–3 fatty acids found in fish are strongly associated with a reduced risk of sudden death among men without evidence of prior cardiovascular disease.

Source Information

From the Division of Preventive Medicine (C.M.A., P.M.R., J.E.M.), the Channing Laboratory (M.J.S., J.E.M., W.C.W., J.M.), and the Division of Cardiovascular Medicine (P.M.R.), Department of Medicine, Brigham and Women's Hospital; the Cardiovascular Division, Department of Medicine, Massachusetts General Hospital (C.M.A.); and the Departments of Nutrition (H.C., M.J.S., W.C.W.) and Epidemiology (M.J.S., J.E.M., W.C.W.), Harvard School of Public Health — all in Boston.

Address reprint requests to Dr. Albert at the Division of Preventive Medicine, Brigham

Fish and Omega-3 Fatty Acid Intake and Risk of Coronary Heart Disease in Women   

Frank B. Hu, MD; Leslie Bronner, MD; Walter C. Willett, MD; Meir J. Stampfer, MD; Kathryn M. Rexrode, MD; Christine M. Albert, MD; David Hunter, MD; JoAnn E. Manson, MD

JAMA, Vol. 287 No. 14, April 10, 2002

http://jama.ama-assn.org/issues/v287n14/abs/joc11695.html

Context  Higher consumption of fish and omega-3 fatty acids has been associated with a lower risk of coronary heart disease (CHD) in men, but limited data are available regarding women.

Objective  To examine the association between fish and long-chain omega-3 fatty acid consumption and risk of CHD in women.

Design, Setting, and Participants  Dietary consumption and follow-up data from 84 688 female nurses enrolled in the Nurses' Health Study, aged 34 to 59 years and free from cardiovascular disease and cancer at baseline in 1980, were compared from validated questionnaires completed in 1980, 1984, 1986, 1990, and 1994.

Main Outcome Measures  Incident nonfatal myocardial infarction and CHD deaths.

Results  During 16 years of follow-up, there were 1513 incident cases of CHD (484 CHD deaths and 1029 nonfatal myocardial infarctions). Compared with women who rarely ate fish (<1 per month), those with a higher intake of fish had a lower risk of CHD. After adjustment for age, smoking, and other cardiovascular risk factors, the multivariable relative risks (RRs) of CHD were 0.79 (95% confidence interval [CI], 0.64-0.97) for fish consumption 1 to 3 times per month, 0.71 (95% CI, 0.58-0.87) for once per week, 0.69 (95% CI, 0.55-0.88) for 2 to 4 times per week, and 0.66 (95% CI, 0.50-0.89) for 5 or more times per week (P for trend = .001). Similarly, women with a higher intake of omega-3 fatty acids had a lower risk of CHD, with multivariable RRs of 1.0, 0.93, 0.78, 0.68, and 0.67 (P<.001 for trend) across quintiles of intake. For fish intake and omega-3 fatty acids, the inverse association appeared to be stronger for CHD deaths (multivariate RR for fish consumption 5 times per week, 0.55 [95% CI, 0.33-0.90] for CHD deaths vs 0.73 [0.51-1.04]) than for nonfatal myocardial infarction.

Conclusion  Among women, higher consumption of fish and omega-3 fatty acids is associated with a lower risk of CHD, particularly CHD deaths.

JAMA. 2002;287:1815-1821

N-3 and N-6 fatty acids in breast adipose tissue and relative risk of breast cancer in a case-control study in Tours, France.

Maillard V, Bougnoux P, Ferrari P, Jourdan ML, Pinault M, Lavillonniere F, Body G, Le Floch O, Chajes V.

Laboratoire de Biologie des Tumeurs, Clinique d'Oncologie-Radiotherapie, Service de Gynecologie-Obstetrique, E.A. 2103, Unite de Recherche Associee Universite-INRA, CHU, Tours, France.

Int J Cancer 2002 Mar 1;98(1):78-83

http://www.ncbi.nlm.nih.gov/entrez/PubMed&list_uids=11857389&dopt=Abstract

Experimental studies have indicated that n-3 fatty acids, including alpha-linolenic acid (18:3 n-3) and long-chain n-3 polyunsaturated fatty acids inhibit mammary tumor growth and metastasis. Earlier epidemiological studies have given inconclusive results about a potential protective effect of dietary n-3 polyunsaturated fatty acids on breast cancer risk, possibly because of methodological issues inherent to nutritional epidemiology. To evaluate the hypothesis that n-3 fatty acids protect against breast cancer, we examined the fatty acid composition in adipose tissue from 241 patients with invasive, nonmetastatic breast carcinoma and from 88 patients with benign breast disease, in a case-control study in Tours, central France. Fatty acid composition in breast adipose tissue was used as a qualitative biomarker of past dietary intake of fatty acids. Biopsies of adipose tissue were obtained at the time of surgery. Individual fatty acids were measured as a percentage of total fatty acids, using capillary gas chromatography. Unconditional logistic regression modeling was used to obtain odds ratio estimates while adjusting for age, height, menopausal status and body mass index. We found inverse associations between breast cancer-risk and n-3 fatty acid levels in breast adipose tissue. Women in the highest tertile of alpha-linolenic acid (18:3 n-3) had an odds ratio of 0.39 (95% confidence intervals [CI] = 0.19-0.78) compared to women in the lowest tertile (trend p = 0.01). In a similar way, women in the highest tertile of docosahexaenoic acid (22:6 n-3) had an odds ratio of 0.31 (95% CI = 0.13-0.75) compared to women in the lowest tertile (trend p = 0.016). Women in the highest tertile of the long-chain n-3/total n-6 ratio had an odds ratio of 0.33 (95% confidence interval = 0.17-0.66) compared to women in the lowest tertile (trend p = 0.0002). In conclusion, our data based on fatty acids levels in breast adipose tissue suggest a protective effect of n-3 fatty acids on breast cancer risk and support the hypothesis that the balance between n-3 and n-6 fatty acids plays a role in breast cancer. Copyright 2001 Wiley-Liss, Inc.

Papers

Low consumption of seafood in early pregnancy as a risk factor for preterm delivery: prospective cohort study

Sjúrur Frói Olsen, associate professor ^a, Niels Jørgen Secher, professor ^b. 

^a Maternal Nutrition Group, Danish Epidemiology Science Centre, Statens Serum Institut, Artillerivej 5, DK-2300 Copenhagen S, Denmark, ^b Perinatal Epidemiology Research Unit, Department of Obstetrics and Gynaecology, Skejby University Hospital, DK-8200 Aarhus N, Denmark

Correspondence to: S F Olsen sfo@ssi.dk

http://bmj.com/cgi/content/full/324/7335/447

Abstract

Objective: To determine the relation between intake of seafood in pregnancy and risk of preterm delivery and low birth weight.

Design: Prospective cohort study.

Setting: Aarhus, Denmark.

Participants: 8729 pregnant women.

Main outcome measures: Preterm delivery and low birth weight.

Results: The occurrence of preterm delivery differed significantly across four groups of seafood intake, falling progressively from 7.1% in the group never consuming fish to 1.9% in the group consuming fish as a hot meal and an open sandwich with fish at least once a week. Adjusted odds for preterm delivery were increased by a factor of 3.6 (95% confidence interval 1.2 to 11.2) in the zero consumption group compared with the highest consumption group. Analyses based on quantified intakes indicated that the working range of the dose-response relation is mainly from zero intake up to a daily intake of 15 g fish or 0.15 g n-3 fatty acids. Estimates of risk for low birth weight were similar to those for preterm delivery.

Conclusions: Low consumption of fish was a strong risk factor for preterm delivery and low birth weight. In women with zero or low intake of fish, small amounts of n-3 fatty acidsprovided as fish or fish oilmay confer protection against preterm delivery and low birth weight.

Introduction

It is important to identify modifiable causes of preterm delivery and fetal growth retardation, which are strong predictors of infants' later health and survival. Observations of high birth weights¹ and long gestations² in the fish eating community of the Faroe Islands suggested that intake of seafood rich in long chain n-3 fatty acids can increase birth weight by prolonging gestation² or by increasing the fetal growth rate.^3-6

Fish oil has been shown in randomised trials ^{7 8} and animal experiments ^{9 10} to have the potential to delay spontaneous delivery and prevent preterm delivery, but the minimum amount of n-3 fatty acids needed to obtain this effect remains to be determined. No detectable effects on fetal growth rate were seen in these trials, ^{7 8} but fish oil was provided only in the second half of pregnancy, and several observational studies have found direct associations between measures of seafood intake in pregnancy and fetal growth rate. ^{5 11-14}

We investigated these issues in a cohort of women in whom seafood intake in early pregnancy was assessed prospectively by a questionnaire method.¹⁵ We tested whether a low intake of seafood in early pregnancy is a risk factor for preterm delivery and low birth weight and whether it is associated with a lower fetal growth rate. We related the findings to quantified intakes of fish and long chain n-3 fatty acids.

Discussion

Low consumption of seafood was a strong risk factor for preterm delivery and low birth weight. The associations were strongest below a daily intake of 0.15 g long chain n-3 fatty acids or 15 g fish.

Strengths and weaknesses
Strengths of the study included that exposure data were collected in a concurrent fashion and long before occurrence of outcome among more than 8000 women, that exposure categories and other analytical conditions were decided a priori, and that analyses took account of nine potential confounding factors.

The main weakness of the study, as with any observational study, was the possibility of confounding that was not adjusted for. Adjustment had little impact on measures of association, but confounding by unmeasured factors cannot be ruled out.

Another weakness was that the assumed values for portion sizes, distributions of fish species in meals, and food contents of nutrients are only approximations to the true values. Imprecise estimates of quantified intake of n-3 fatty acids are thus inevitable. Although this imprecision is unlikely to explain the steep decline in risk at the low end of the exposure distribution, it may contribute to the observed "bending" of the relation if imprecision increases with increasing exposure, a possibility that cannot be ruled out.

Alternative strategy
The alternative strategy was free of these assumptions as it simply used the questions on food frequency to define four groups with large differences in exposure; the questions had been shown to be strong and mutually independent predictors of n-3 fatty acids measured in erythrocytes in the same population.¹⁵ It is therefore reassuring that this strategy corroborated the finding of a steep decline in risk across the lowest exposure groups, although with only four groups it was not possible to draw conclusions about levelling off at high exposures.

Comparisons with other studies
Overall, the findings agree with the randomised trials showing that consumption of fish oil in pregnancy can increase birth weight by prolonging gestation and reduce the risk of recurrence of preterm delivery. ^{7 8} The finding that the dose-response relations were strong at low exposures corroborates two earlier studies. A reduction in early delivery was seen in women who had received only 0.1 g n-3 fatty acids (along with other substances) a day from week 20 of gestation.^20-23 An association was seen between duration of pregnancy and a biomarker for intake of marine n-3 fatty acids (fatty acids measured in erythrocyte lipids) in Danish women, whereas no such association could be detected in Faroese women with a substantially higher intake, suggesting a stronger association at low exposures.²⁴

A case-control study in the same population could not detect any association between seafood intake in pregnancy and risks of preterm birth²⁵; unlike the present study, however, this study assessed dietary intake retrospectively after delivery, which may have distorted the results and led to the null finding.

Several observational studies have found associations between measures of maternal seafood intake and fetal growth rate. ^{5 11-14} In the randomised trials, where fish oil was provided after week 16-20 of gestation, no effects were seen on fetal growth rate. ^{7 8} The observational data could therefore possibly be explained either by effects of n-3 fatty acids exerted before week 16-20 or by effects of other substances in seafood. Our study could substantiate neither of these two possibilities, as the associations between seafood consumption in early pregnancy and fetal growth rate tended to disappear after adjustment for potential confounders.

Randomised controlled trials to examine the dose-response relations between long chain n-3 fatty acids and timing of delivery and preterm risk are warranted.

Commercial Fish: Eat Up, Despite Low Levels Of Mercury

Source University of Rochester (http://www.rochester.edu/)

Date posted 8/27/1998

http://www.sciencedaily.com/releases/1998/08/980827074214.htm

Even though the world's fish contain slight amounts of mercury, eating lots of fish carries no detectable health risk from low levels of the substance, even for very young children and pregnant women, concludes the most comprehensive study of the subject yet.

Age-Related Cognitive Decline and Fish Consumption - Omega-3 Fatty Acids  Improve Cognitive Function 

Life Enhancement, June 2001, pp 12-15

In Gulliver's Travels, Jonathan Swift described the Immortals from Luggnagg thus: ". . . they never can amuse themselves with reading, because their memory will not serve to carry them from the beginning of a sentence to the end . . . ." While the Luggnaggs may make your memory look sharp by comparison, it's probably still safe to bet that you forget where you put your car keys from time to time. After all, we all have our memory lapses.

The sad fact is that, as we age, our memory and our cognitive abilities in general are destined to decline. But much research demonstrates that certain fatty acids, especially the oils found in cold-water fish, can be used to improve brain function, reduce memory loss, and retard cognitive decline. 

AGING BRINGS COGNITIVE DECLINE
Scientists are still not sure how or why we age. But one thing is for sure - there's no way around getting older. As we age, we are more likely to forget birthdays, appointments, conversations, and other important information. This so-called age-related cognitive decline (ARCD) is marked by mild deterioration in our memory, our performance of simple daily tasks, and the speed of our mental processing.

Certain fatty acids, especially the  oils found in cold-water fish, can be used to improve brain function,  reduce memory loss, and retard  cognitive decline. 

The causes of ARCD are largely unknown, but recent research suggests that certain deleterious conditions or activities, such as high blood pressure, high levels of free radicals (reactive molecules that cause oxidative damage), metabolic disorders, smoking, low physical activity, and lack of mental challenge, may accelerate the rate of memory loss and mental decline.

But we don't have to sit back and take the aging process and its ensuing memory loss complacently. On the contrary, we can and should be proactive, taking advantage of current scientific research that suggests that we can prevent or retard ARCD. In this regard, it is instructive to consider the role that fats and fatty acids may play in improving cognitive function.

THE BRAIN NEEDS FATTY ACIDS
There appears to be a widespread public misconception about dietary fat. The plain truth is that the body and mind need dietary fat, in reasonable quantities, to function optimally (or even at all - without fat, we would die). Dietary fats are often referred to as fatty acids, which simply means that a long fat molecule has an acidic group attached to one end. These fats come in a variety of types, including saturated (meaning that there are no double bonds between carbon atoms in the chain), monounsaturated (one double bond), and polyunsaturated (two or more double bonds). If this seems overly technical, just remember that saturated fats, such as butter, tend to be solids at room temperature, and unsaturated ones are usually oils.

Monounsaturated fats (e.g., olive, canola, and peanut oils) are generally considered to be healthier than polyunsaturated fats (e.g., sunflower, safflower, and corn oils). As we will see, however, members of a certain class of polyunsaturated fats, the omega-3 fatty acids, have many beneficial effects, particularly with respect to cognition and memory; they are also considered to be heart-healthy.

It has long been known that dietary fats are beneficial to brain function. Brain tissue is especially rich in these vital nutrients, which help to ensure normal nerve-cell function, and the brain does not function optimally if it is deprived of them. For example, when laboratory rats are maintained on diets deficient in polyunsaturated fatty acids such as docosahexaenoic acid (it's an omega-3 fatty acid found in fish oil), their learning and memory capabilities are significantly impaired.¹

A separate study shows that rats initially maintained on a diet deficient in fish oil have poor learning and memory skills. When they are transferred to a diet supplemented with DHA, however, they demonstrate dramatic improvement in learning and memory.²

DHA is one of the primary fatty acids found in fish oils. This molecule is very important in the formation of the cellular membranes of nerve cells. When DHA is in short supply, the structural and functional integrity of the nerve cell is compromised. Thus it is not surprising that a number of studies demonstrate that DHA is required for normal brain development in humans. In studies with infants, it has been found that newborns supplemented with DHA exhibit improved brain development, which allows them to process information more rapidly.³

Much of the work with DHA thus far has been performed on laboratory animals and has focused on the memory of older animals. For example, when the diet of older rats is supplemented with DHA, their memory improves dramatically. After only four days of supplementation, they need only half as much time to find their way out of a maze as control rats that were fed palm oil with no DHA.⁴ Based on this and other information, many researchers believe that an ample intake of omega-3 fatty acids such as DHA may be especially beneficial in protecting against ARCD in humans.

UNCHECKED ARCD MAY PROGRESS TO DEMENTIA
We all realize that memory impairment is a natural part of growing older, and minor memory lapses are common. Cognitive decline as a result of aging can mean many different things. The type of information that is least easily recalled is generally nonessential and may simply reflect "forgetfulness." However, minor memory loss that progresses to a level where recent events are not remembered and everyday tasks are not performed properly may signal the onset of dementia.

DHA is one of the primary fatty  acids found in fish oils. This  molecule is very important in the  formation of the cellular  membranes of nerve cells. 

Dementia is a collective term that denotes memory loss along with a decline in intellectual functions, such as thinking and reasoning, in ways that interfere with normal activities such as cooking, household chores, and personal grooming. A persistent, steady decline in these areas may signal the onset of Alzheimer's disease, for example. 

MEMORY DECLINE DUE TO AGING IS NOT INEVITABLE
A recent paper in the Archives of Neurology by Dr. Scott Small of Columbia University summarizes the relationships between cognition, age, and memory loss succinctly:⁵ "There is little question that memory declines with age. Although there is continued debate as to whether memory decline is normal, epidemiological data suggest that components of memory decline are not inevitable . . . ." Dr. Small further suggests that, as research progresses and the specific populations of neurons in regions of the brain responsible for memory loss are identified, more effective treatments for memory loss can be devised. One natural approach that we already know about for enhancing memory function is the omega-3 fatty acids present in fish oils.

OMEGA-3 FATTY ACIDS IMPROVE COGNITION
Current research efforts have identified a number of potential memory boosters. Many of these are fish oils rich in omega-3 fatty acids, such as DHA. In fact, previous studies suggest that DHA levels in the brain decrease with advancing age⁶ and that humans with senile dementia treated for six months with fish-oil capsules (1400 mg of DHA per day) show improvement in intellectual function.⁷

A recent report demonstrates that the levels of DHA are lower in the brains of Alzheimer's patients than in those of normal elderly individuals. The DHA levels are typically lower in the blood plasma of AD patients also. These facts suggest that low DHA levels may be a risk factor for developing Alzheimer's disease.⁸

These facts suggest that low DHA  levels may be a risk factor for  developing Alzheimer's disease.

A separate study indicates that high fish consumption is positively correlated with cognitive function in older males.⁹ Researchers in Holland followed the dietary habits of 342 men from 1990 to 1993 and assessed their rate of cognitive decline during that period. Of a number of different dietary factors that were considered, only high fish consumption seemed to prevent a decrease in cognitive function over the study period.

OUR DIET IS DEFICIENT IN DHA
Not all fish are equally beneficial in this respect. Cold-water fish, such as mackerel, herring, salmon, and tuna, have the highest levels of omega-3 fatty acids and contribute the largest amount of DHA to one's diet. A proposed recommended amount of DHA (combined with another fish oil, eicosapentaenoic acid, or EPA) is 0.65 g per day, which corresponds to two to three servings of cold-water fish per week.¹⁰ One study suggests that attaining this intake of DHA in the United States would require a quadrupling of our fish consumption.¹¹ Since it is unlikely that this will happen anytime soon, if ever, the majority of our population will probably continue to receive an inadequate supply of omega-3 fatty acids.

Additional Benefits of Omega-3 Fatty Acids
Many different health benefits are attributed to the versatile omega-3 fatty acids.¹³ Various studies have shown that they can help:

Although our bodies are capable of making DHA, this process is inefficient. The precursor to DHA is alpha-linolenic acid (ALA), a molecule that the body cannot synthesize, so it must be consumed in the diet (walnuts and soybeans are two of the better sources). But ALA is converted to DHA at a rate of only 3.8%.¹² Given that Americans typically consume only 1.1­1.6 g of ALA per day (the recommended intake is 2.2 g), it is most unlikely that our bodies are getting sufficient amounts of DHA from that source.11 An inadequate supply of DHA may adversely affect organs such as the brain, eyes, and nervous system, which rely on this essential molecule.

References 

1. Geiner RS, Moriguchi T, Hutton A, Slotnick BM, Salem N Jr. Rats with low levels of brain docosahexaenoic acid show impaired performance in olfactory-based and spatial learning tasks. Lipids 1999;34:S239-S243. 
2. Gamoh S, Hashimoto M, Sugioka K, et al. Chronic administration of docosahexaenoic acid improves reference memory-related learning ability in young rats. Neuroscience 1999;93:237-41. 
3. Werkman SH, Carlson SE. A randomized trial of visual attention of preterm infants fed docosahexaenoic acid until nine months. Lipids 1996;31:91-7. 
4. Lim S-Y, Suzuki H. Intakes of dietary docosahexaenoic acid ethyl ester and egg  phosphatidylcholine improve maze-learning ability in young and old mice. J Nutr 2000;130:1629-32. 
5. Small SA. Age-related memory decline. Arch Neurol 2001;58:360-4. 
6. Suzuki H, Hayakawa S, Wada S. Effect of age on the modification of brain polyunsaturated fatty acids and enzyme activities by fish oil diet in rats. Mech Aging Devel 1989;50:17-25. 
7. Miyanaga K, Ynoemura K, Takagi T, et al. Clinical effects of DHA in demented patients. J Clin Ther Med 1995;11:881-901. 
8. Conquer JA, Tierney MC, Zecevic J, Bettger WJ, Fisher RH. Fatty acid analysis of blood plasma of patients with Alzheimer's disease, other types of dementia, and cognitive impairment. Lipids 2000;35:1305-12. 
9. Kalmijn S, Feskens EJ, Launer LJ, Kromhout D. Polyunsaturated fatty acids, antioxidants, and cognitive function in very old men. Am J Epidemiol 1997;145:33-41. 
10. Simopolous AP, Leaf A, Salem N Jr. Essentiality of and recommended dietary intakes for omega-6 and omega-3 fatty acids. Ann Nutr Metab 1999;43: 127-130. 
11. Kris-Etherton PM, Taylor DS, Yu-Poth S, et al. Polyunsaturated fatty acids in the food chain in the United States. Am J Clin Nutr 2000;71:179S-188S. 
12. Gerster H. Can adults adequately convert alpha-linolenic acid (18:3n-3) to eicosapentaenoic acid (20:5n-3) and docosahexaenoic acid (22:6n-3)? Int J Vitam Nutr Res 1998;68:159-73.

13. 1.Connor WE. Importance of w-3 fatty acids in health and disease. Am J Clin Nutr 2000;71:171S-175S.

    

Advantages of a Mediterranean Diet

An additional approach to enhancing cognition may be to adopt a "Mediterranean diet" rich in unsaturated fatty acids. While such a diet has long been advocated by cardiologists and nutritionists for reasons of heart health, recent research indicates that it may decrease the rate of memory loss as well. A study of 278 elderly individuals (65­84 years of age) from Casamassima in rural southern Italy revealed a strong correlation between high monounsaturated fat intake and improved cognitive performance.1 On average, these individuals consumed 33% of their total calories in the form of fat, and 17.6% of their total calories came from monounsaturated fatty acids. Of the latter amount, 85% was derived from olive oil, which means that 15% of their total calories came from olive oil.* These individuals exhibited a very low incidence of ARCD. 

1. Solfrizzi V, Panza F, Torres F, et al. High monounsaturated fatty acids intake protects against age-related cognitive decline. Neurology 1999;52:1563-9.

Intake of Fish and Omega-3 Fatty Acids and Risk of Stroke in Women  

Hiroyasu Iso, MD, PhD; Kathryn M. Rexrode, MD, MPH; Meir J. Stampfer, MD, DrPH; JoAnn E. Manson, MD, DrPH; Graham A. Colditz, MD, DrPH; Frank E. Speizer, MD; Charles H. Hennekens, MD, DrPH; Walter C. Willett, MD, DrPH

JAMA. 2001;285:304-312

http://jama.ama-assn.org/issues/v285n3/abs/joc92011.html

Context  Some prospective studies have shown an inverse association between fish intake and risk of stroke, but none has examined the relationship of fish and omega-3 polyunsaturated fatty acid intake with risk of specific stroke subtypes.

Objective  To examine the association between fish and omega-3 polyunsaturated fatty acid intake and risk of stroke subtypes in women.

Design, Setting, and Subjects  Prospective cohort study of women in the Nurses' Health Study cohort, aged 34 to 59 years in 1980, who were free from prior diagnosed cardiovascular disease, cancer, and history of diabetes and hypercholesterolemia and who completed a food frequency questionnaire including consumption of fish and other frequently eaten foods. The 79 839 women who met our eligibility criteria were followed up for 14 years.

Main Outcome Measure  Relative risk of stroke in 1980-1994 compared by category of fish intake and quintile of omega-3 polyunsaturated fatty acid intake.

Results  After 1 086 261 person-years of follow-up, 574 incident strokes were documented, including 119 subarachnoid hemorrhages, 62 intraparenchymal hemorrhages, 303 ischemic strokes (264 thrombotic and 39 embolic infarctions), and 90 strokes of undetermined type. Among thrombotic infarctions, 90 large-artery occlusive infarctions and 142 lacunar infarctions were identified. Compared with women who ate fish less than once per month, those with higher intake of fish had a lower risk of total stroke: the multivariate relative risks (RRs), adjusted for age, smoking, and other cardiovascular risk factors, were 0.93 (95% confidence interval [CI], 0.65-1.34) for fish consumption 1 to 3 times per month, 0.78 (95% CI, 0.55-1.12) for once per week, 0.73 (95% CI, 0.47-1.14) for 2 to 4 times per week, and 0.48 (95% CI, 0.21-1.06) for 5 or more times per week (P for trend = .06). Among stroke subtypes, a significantly reduced risk of thrombotic infarction was found among women who ate fish 2 or more times per week (multivariate RR, 0.49; 95% CI, 0.26-0.93). Women in the highest quintile of intake of long-chain omega-3 polyunsaturated fatty acids had reduced risk of total stroke and thrombotic infarction, with multivariate RRs of 0.72 (95% CI, 0.53-0.99) and 0.67 (95% CI, 0.42-1.07), respectively. When stratified by aspirin use, fish and omega-3 polyunsaturated fatty acid intakes were inversely associated with risk of thrombotic infarction, primarily among women who did not regularly take aspirin. There was no association between fish or omega-3 polyunsaturated fatty acid intake and risk of hemorrhagic stroke.

Conclusions  Our data indicate that higher consumption of fish and omega-3 polyunsaturated fatty acids is associated with a reduced risk of thrombotic infarction, primarily among women who do not take aspirin regularly, but is not related to risk of hemorrhagic stroke.

Eating Fatty Fish May Reduce Risk Of Prostate Cancer

http://unisci.com/stories/20012/0601013.htm

Consumption of fatty fish such as salmon, herring and mackerel could reduce the risk of prostate cancer, report the authors of a research letter in this week's issue of The Lancet.

Fatty fish consumption and risk of prostate cancer

Paul Terry, Paul Lichtenstein, Maria Feychting, Anders Ahlbom, Alicja Wolk

The Lancet, Volume 357, Number 9270,  02 June 2001

http://www.thelancet.com/journal/journal.isa