Circulating Long-Chain Omega-3 Fatty Acids and Incidence of Congestive Heart Failure in Older Adults: The Cardiovascular Health Study

Mozaffarian , D. et al., Annals of Internal Medicine, 155: 160-170 , 2011

Harvard School of Public Health, Boston, MA, USA

Summary :

The primary focus of the present study was to determine if higher blood levels of the long-chain omega-3 fatty acids as EPA/DPA/DHA in a large number of adults who were free of heart disease at entry may show a relationship to their risk of developing congestive heart failure (CHF) with time. For this purpose, 2735 US adults aged 65 years and over (average age of 75 years, both genders) were randomly selected who were free of heart disease when recruited. Blood samples were taken and the fatty acid compositions (including omega-3 fatty acids) were determined in the blood serum phospholipid – a recognized biomarker for omega-3 status . This biomarker reflects the dietary intake of long-chain omega-3 fatty acids (eg, from fish/seafood) and the intake and the somewhat limited conversion of dietary alpha-linolenic acid omega-3 to the long-chain omega-3 fatty acids as EPA (eicosapentaenoic acid) plus DPA (docosapentaenoic acid) plus DHA (docosahexaenoic acid).The subjects were followed for 10 years by annual clinical examinations and interim phone calls. Appropriate clinical criteria for confirming a diagnosis of CHF were employed.

After adjusting for various factors (age, gender, diabetes, physical activity, body mass, others), higher long-chain omega-3 levels in the circulation (measured in serum phospholipid) were found to be associated with a much lower likelihood of developing CHF over the next several years. At seven years for example, those subjects having EPA levels in the highest quartile (top 25 %) exhibited a 52 % lower risk for developing CHF when compared to those in the lowest quartile (lowest 25 % with respect to EPA levels). Those in the highest quartile with respect to circulating levels of DPA , DHA, and total long-chain omega-3 (sum of EPA plus DPA plus DHA) exhibited corresponding lower risks for developing CHF of 39 %, 36 %, and 49 %, respectively. The authors concluded that higher circulating levels of each of the three individual long-chain omega-3 fatty acids and their sum are associated with a lower incidence of CHF in older adults.

Dr. Holub’s Comments :

This extensive population-based study supports recent population and intervention trials which have supported the benefits of increasing long-chain omega-3 intakes in reducing the onset of CHF and/or slowing its progression. Numerous mechanisms have been proposed by which omega-3 may exhibit their benefits in relation to heart failure as very recently reviewed by Jarreau and colleagues (Curr. Heart Failure Rep., in press (2011)). The present study from the Harvard team also indicates a considerable benefit offered by higher levels of DPA (22:5 n-3) in addition to EPA and DHA. There are other population studies which have supported a protective effect of higher levels of circulating DPA against heart disease and stroke risk. In general, dietary intakes of DPA are very low (as compared to DHA/EPA in most populations) although it can be formed in the human body to some limited extent via metabolism (desaturation and elongation reactions) from alpha-linolenic acid omega-3 as found in certain plant-based food sources. Populations such as the Inuit who consume considerable amounts of mammalian seafood (eg, seal meat) have rather high intakes of DPA as well as EPA/DHA.

Effect of Dietary Fish Oil on Atrial Fibrillation after Cardiac Surgery

Farquarharson , A. L. et al., American Journal of Cardiology , 108: 851-856 , 2011

Discipline of Medicine, University of Adelaide and Dept. of Cardiology, Royal Adelaide Hospital, Adelaide, Australia

Summary :

Atrial fibrillation is a relatively common heart rhythm disorder which often occurs as a result of cardiac surgery. It is associated with extended stays in the intensive care unit (ICU) and the overall duration of hospitalization as well as increased mortality. Since an anti-arrhythmic effect of EPA/DHA omega-3 fatty acids has been indicated in multiple animal and some human studies, the present investigation was conducted to evaluate the potential beneficial effects of supplementation with omega-3 prior to cardiac surgery on the post-surgical outcomes. Patients (200) scheduled for coronary artery bypass surgery (CABG) or valve repair were randomly assigned to receive a placebo capsule lacking omega-3 (control group) or 2.7 gm EPA plus 1.9 gm DHA daily for 21 days prior to surgery. Supplementation was maintained for 6 days after surgery or until discharge from hospital (whichever came first).

The overall incidence of in-hospital atrial fibrillation (AF) was found to be 48 % for the control group and 37 % in those given EPA/DHA with no statistically-significant difference between the two groups. A trend for a delayed time to occurrence of AF (by 29-34 %) was found in the omega-3 group as compared to controls which did not quite reach statistical significance. A statistically-significant lesser period of time in the ICU post-surgery was found for patients previously given omega-3 (average of 67 hours) as compared to those in the control group (average of 95 hours). The omega-3 group also showed much higher levels of omega-3 in samples of cardiac tissue when taken at the time of surgery for fatty acid analyses (EPA plus DHA averaged at 8.14 % of total fatty acids in heart tissue phospholipid for the omega-3 group as compared to only 4.94 % for the controls). The authors concluded that the lessened period of time spent in the ICU following cardiac surgery resulting from the pre-surgical supplementation with EPA/DHA is likely to be significant for health costs because of the high costs associated with intensive care.

Dr. Holub’s Comments :

It is of interest to note that, despite the fact that the omega-3 supplementation contained much more EPA than DHA, the DHA levels in the heart tissue samples (analyzed in the phospholipid fraction) from the omega-3 patients had three times more DHA than EPA (6.10 % as DHA and only 2.03 % as EPA). It is possible that the beneficial effects seen with omega-3 supplementation could be mediated more by the enrichment of DHA in cardiac tissue. However, multiple factors over and above decreased AF due to omega-3 enrichment in cardiac tissue could likely be responsible for the reduced time of patients in the ICU following surgery. The various benefits of omega-3 which are external to their accumulation in cardiac tissue might be due to cellular accumulations of EPA and/or DHA and the formations of their bio-active metabolites (eg, anti-inflammatory resolvins , protectins , other products).

Moderate Doses of EPA and DHA from Re-esterified Triacylglycerols but not from Ethyl-Esters Lower Fasting Triacylglycerols in Statin-Treated Dyslipidemic Subjects : Results from a Six Month Randomized Controlled Trial

Schuchardt , J. P. et al., Prost., Leuk. and Essential Fatty Acids, in press , 2011

Inst. of Food Science and Human Nutrition, Leibniz University Hanover, Hanover, Germany

Summary :

It is very well established that supplementation with EPA/DHA omega-3 can markedly lower fasting serum triglyceride (triacylglycerol) levels in those who are or are not receiving medication with blood cholesterol-lowering statins (Holub, Can. Medical Assoc. J., 177: 604-605 (2007)). Furthermore , omega-3 ‘concentrates’ are now commercially available in both the ‘re-esterified triacyglycerol’ (TG) and the ‘ethyl ester’ (EE) forms. Recent studies have indicated a moderately better bioavailability of the TG when compared to the EE form at identical daily doses when blood measures for EPA/DHA levels are measured at baseline and after an extended period of daily supplementation. In the present clinical trial, the investigators directly compared the blood triglyceride (triacylglycerol) – lowering ability of EPA/DHA as the TG vs. EE form at equal doses/day in statin-treated patients.

For this purpose, 150 patients were randomly assigned to receive a ‘placebo’ (lacking EPA/DHA) or 1.68 gms/day of EPA/DHA (1.01 gms EPA plus 0.67 gms DHA) via supplementation using either the TG (re-esterified triacylglycerol) or the EE form. Fasting blood serum lipid levels were measured at baseline and after 3 and 6 months following supplementation. Based on capsule counting, compliance to supplementation was 97-98 % across the groups. No significant changes were found in total-, LDL-, or HDL-cholesterol levels following supplementation. No change was found in the fasting triglyceride levels after 3 or 6 months relative to baseline in the placebo group. However, a statistically-significant decrease in fasting triglyceride levels relative to baseline levels was found at 3 months (by 16.7 %) and at 6 months (by 18.7 % ) in the TG group whereas the lesser reductions in the EE group (by 8.8 % at 3 months and 9.4 % at 6 months) did not reach statistical significance. The authors considered that the observed differences between the two omega-3 formulations was likely due to a better bioavailability of the TG over the EE form.

Dr. Holub’s Comments :

The present clinical trial suggests that recommended daily doses for omega-3 intakes as EPA plus DHA via supplementation may need to pay consideration to the particular form of the omega-3 fatty acid(s) being ingested. Other considerations would be the cost per unit (amount) of EPA/DHA being consumed since , despite the apparent moderately lower bioavailability and efficacy of the oral EE form as indicated in this study, cost comparisons of highly enriched omega-3 concentrates of equal amounts often show a somewhat greater cost for the TG form. This study also supports the value of blood measures for omega-3 status to ensure that target ranges are being attained. Finally, future clinical trials which mimic the present study (in evaluating efficacy and bioavailability) will be of utmost interest so as to include other forms of omega-3 concentrates that are becoming available commercially (such as the free fatty acid and phospholipid forms of EPA and DHA).

Preliminary Evidence that Acute Long-Chain Omega-3 Supplementation Reduces Cardiovascular Reactivity to Mental Stress: A Randomized and Placebo Controlled Trial

Ginty, A. and Conklin, S. M., Biological Psychology . in press ,2011

Dept. of Psychology and Neuroscience Pgm., Allegheny College, Meadville, PA, USA

Summary :

It is known that increased intakes of DHA plus EPA from fish/fish oils have been associated with the improvement of various risk factors for cardiovascular disease including the reduction of serious cardiac outcomes in many trials. Since excessive cardiovascular reactions to various mental stressors have been documented which are considered to adversely affect the cardiovascular system (including elevated blood pressures, etc ), the present study was designed to determine the potential effect of EPA/DHA omega-3 supplementation on the cardiovascular reactivity to mental stress in young and healthy adults.

For this purpose, 43 college students (average age of 20 years) were randomly assigned to receive daily supplementation with a corn oil placebo (control group) or omega-3 providing 1400 mg of EPA/DHA daily (1000 mg EPA plus 400 mg DHA) for a treatment period of 21 days. The stress reactivity testing was performed at baseline and 21 days later and consisted of measuring cardiovascular measures (including blood pressures, heart rates ) upon subjecting the test subjects to a psychological stress task after a pre-rest interval followed by a recovery period. Interestingly, the mean arterial pressure reactivity in response to stress was significantly reduced following supplementation with EPA/DHA but not in the placebo (control) group. The stress mean arterial pressure (MAP) rose by an average of 13.0 mm Hg above resting values at baseline but by only 7.3 mm Hg following omega-3 supplementation. The authors state this study to be the first to show such positive effects of EPA/DHA supplementation at relatively low-doses and for short-term intervals on cardiovascular reactivity to mental stress in young healthy adults.

Dr. Holub’s Comments :

The present results indicate that yet another mechanism by which long-chain omega-3 fatty acids as EPA/DHA may reduce cardiovascular disease and ‘hard events’ (incl. myocardial infarctions and sudden cardiac death ) is by alleviating the impact of mental stressors on the cardiovascular system and its reactivity to such. It is possible that EPA/DHA and/or their metabolites (eicosanoids, resolvins, protectins) may act within neural tissue or elsewhere to exhibit ameliorating effects on various mental stressors. The daily dose of EPA plus DHA (1400 mg/day) as used in the present trial is many fold higher than average daily intakes in North America (approx. 130 – 150 mg/person) yet within the range of daily intakes for a significant number of adults living in Japan (via fish/seafood).

Omega-3 Fatty Acids Eicosapentaenoic Acid and Docosahexaenoic Acid in the Management of Hypercalciuric Stone Formers

Ortiz-Alvarado, O. et al., Urology , in press , 2011

Dept. of Regional Urology , The Cleveland Clinic , Cleveland, Ohio, USA

Summary :

Urolithiasis is a medical condition where urinary calculi (‘stones’) are formed and locate in various regions of the urinary system (including the kidney and ureter). Patients which present with kidney stones often exhibit high urinary levels of calcium as a frequent abnormality. Diets rich in omega-6 fatty acids contribute to higher levels of the omega-6 fatty acid in the body tissues (the kidney and elsewhere) known as AA ( arachidonic acid). AA is metabolically converted to ‘eicosanoids’ which have been implicated in promoting the formation of kidney stones. Since omega-3 fatty acids suppress AA levels in the body and the conversion of AA to its corresponding eicosanoids, it was of interest to determine if supplementation with DHA/EPA omega-3 might decrease urinary calcium levels and the excretion of oxalate since these are involved in stone formation.

In the present study, 29 patients (average age of 43 years) with high levels of urinary calcium and calcium-containing stones were managed via dietary advice (with respect to fluid intakes, citric juices , other recommendations) plus daily supplementation with 1200 mg of fish oil (containing DHA plus EPA) with an average follow-up period of 9.9 months. Relative to baseline levels, an average reduction of 29 % was found in urinary calcium excretion within 6 months of dietary intervention with fish oil along with a significant decrease in urinary oxalate excretion. The authors concluded that dietary advice and the use of DHA/EPA omega-3 via daily fish oil supplementation may reduce the urinary calcium and oxalate levels in hypercalciuric stone formers.

Dr. Holub’s Comments :

While interesting and novel, this study has a number of limitations in the design of the clinical trial which significantly compromise its potential value as a basis for promoting the therapeutic effect of DHA/EPA omega-3 fatty acids in hypercalciuric stone formers. Firstly, the investigators did not include a ‘control’ group of subjects so as to show that no dietary and/or no omega-3 treatment was without effect over the same time interval on the urinary measures as performed. Secondly, since the dietary treatment was done simultaneously with the omega-3 supplementation, one cannot assess the relative impact of each (if any) on the reduced levels of urinary calcium and oxalate. Thirdly, the authors refer to the use of 1200 mg fish oil per day as the supplemental dose but do not provide specific information on the daily dose of DHA and/or EPA in mg/day.

Thirteen-Year Prospective Study Between Fish Consumption , Long-Chain N-3 Fatty Acids Intakes and Cognitive Function

Kesse-Guyot, E. et al., J. Nutr. ,Health and Aging ,15: 115-120 , 2011

INSERM , Human Nutrition Research Ctr.of Ile de France, Paris, France

Summary :

This prospective population-based study from Paris, France involved 3,294 adults (both genders, average age 64 years). Initially, the subjects had dietary assessments to determine their intakes of fish/seafood as well as the corresponding long-chain omega-3 fatty acids . The subjects were followed for an average of 7.5 years (up to 13 years later). The assessment of cognitive functioning included the MMSE (French version) and a 5-word test for immediate and delayed verbal memory and recall. Further, they completed a self-reported questionnaire for memory complaints using McNair’s Cognitive Difficulties Scale.

Those in the top 25 % of the population with respect to dietary intakes of the total long-chain omega-3 fatty acids exhibited a 28-32 % less frequent complaints regarding cognitive difficulties as compared to those with the lower (bottom 25 %) omega-3 intakes. The former group also showed a poor score on the MMSE evaluation less frequently but this did not reach statistical significance. Those in the top 25 % for DHA and EPA intakes exhibited a 19-25 % less frequency in self-reported cognitive difficulties while a 26-31 % lesser frequency was apparent amongst those with the higher intakes of EPA. The authors concluded that cognitive complaints are less frequent among the elderly with higher intakes of long-chain omega-3 fatty acids as assessed up to 13 years earlier.

Dr. Holub’s Comments :

This population study from France is of considerable interest with implications for improved public health care for the aging population since cognitive complaints are often a early signal for cognitive decline. This study suggests than higher intakes of (DHA plus EPA) can potentially delay and/or retards such age-related cognitive decline. It is noted that the average intakes of DHA and EPA in this group of subjects was 280 mg and 150 mg, respectively, per day. Those in the top 25 % had considerably higher omega-3 intakes. Current average intakes amongst the elderly in North America (and many other global communities) are well below one-half of the average intakes in the population as studied in the present report.

Long Chain Omega-3 Polyunsaturated Fatty Acids Supplementation in the Treatment of Elderly Depression : Effects on Depressive Symptoms , on Phospholipids Fatty Acids Profile and on Health-Related Quality of Life

Rondanelli et al., J. Nutr., Health and Aging , 15: 37-44 ,2011

Dept. of Applied Health Sciences , Section of Human Nutrition and Dietetics, Faculty Of Medicine, University of Pavia, Pavia, Italy

Summary :

The present intervention trial evaluated the potential for omega-3 supplementation to improve depressive symptoms and health-related quality of life in elderly female patients. This work was of particular interest since the prevalence of depressive symptoms in elderly hospitalized patients often approaches up to 30% or more. The target group for this study were 46 depressed elderly patients (all female) in a nursing home in Italy ranging in age from 66-95 years .The study was a double-blind randomized trial with one group of subjects assigned to receive a placebo (control group) and the other group receiving supplementation (liquid oil) daily with 2.5 grams omega-3 daily (1.7 gm EPA plus 0.8 gm DHA) for two months. Depressive symptoms were assessed through the use of the Geriatric Depression Scale (GDS) before and after the two month treatment period. A significant lowering of the GDS at two months was found for those in the omega-3 group but not for the controls. Further, 44 % of the patients in the omega-3 group showed an improvement in social functioning and 0 % worsened as compared to 5 % improved and 52 % worsened in the placebo group. In terms of mental health, 83 % of the patients improved in the omega-3 group while 17 % worsened. In contrast, only 38 % improved in the placebo group while 52 % worsened. As expected, the EPA and DHA levels in the blood samples rose in the omega-3 group but not in the placebo group (controls). No relevant side effects were observed with omega-3 supplementation.

The authors concluded that supplementation with omega-3 fatty acids (as EPA plus DHA) in elderly female patients reduces the occurrence of depressive symptoms and improved their health-related quality of life.

Dr. Holub’s Comments :

The significant reduction in depressive symptoms in this elderly female population residing in a nursing home with omega-3 supplementation and the improvement in quality of life (physical and mental functioning) implies that such supplementation should be considered for implementation as standard nutritional care within and outside such institutions. Such over-the-counter omega-3 supplementation can be purchased (retail) in North America at many outlets for a much lesser cost than numerous other supplements. Many in the elderly population prefer quality liquid oils containing EPA/DHA rather than encapsulated products for ease of swallowing. Of course, proper storage and oxidative stability is important.

Serum Phospholipid Fatty Acids and Prostate Cancer Risk : Results from the Prostate Cancer Prevention Trial

Brasky,T.M. et al., Am. J. Epidemiol., 173: 1429-1439 , 2011

Fred Hutchinson Research Ctr., Seattle, WA, USA

Summary :

In this population study on males (aged 55-84 years) across various centers in the US, the possible relation between polyunsaturated levels (and trans fatty acids) in blood serum lipid samples and the 7-year prevalence of prostate cancer was monitored.

The authors reported that higher levels of DHA (one of the two predominant omega-3 fatty acids found in fish ) as measured in blood samples were positively correlated with the risk of high-grade prostate cancer but not low-grade prostate cancer in US men. It is noted that 7.5 % of all prostate cancers in this population study were considered as high grade whereas 92.5 % were low-grade . Further, higher intakes of ‘trans’ fatty acids (common constituents of processed and fast foods containing partially-hydrogenated vegetable oils) were associated with a lower risk of high-grade prostate cancer.

Dr. Holub’s Comments :

Both of these findings (ie, positive relation of blood DHA omega-3 levels and negative relation of trans fatty acids to high-grade prostate cancer risk ) were most surprising (on first notice) since they were contrary to expectations from almost all the many previous studies on this topic.

The following points need to be considered:

1) The authors did not directly measure the intakes of fish or the intake of the fish/seafood -derived omega-3 fatty acids (DHA plus EPA).

2) Many previous studies have reported protective effects of both fish and dietary (DHA plus EPA) for total prostate cancer risk. Some have shown no increase in risk and others a decrease in prostate-cancer related mortality. It is noted that a major US study from the Harvard Medical School as published in 2008 (Am. J. Clin. Nutr., 88: 1297-1303(2008)) on 20,167 men found no relation of fish intakes to prostate cancer incidence with a 48 % lower risk of death from prostate cancer in those with the disease who consumed fish 5 or more times per week. A similar association was found for seafood-derived omega-3 fatty acid intakes and prostate cancer mortality. The following quote is taken from a very recent review of the many studies on the topic wrt fish intakes from Szymanski et al. (Am. J. Clin. Nutr., 92: 1223-1233 (2010) who concluded: “Our analyses provide no strong evidence of a protective association of fish consumption with prostate cancer incidence but showed a significant 63% reduction in prostate cancer-specific mortality.”

3) It is noted that it was the ‘blood level’ of DHA which (if higher) was associated with a greater risk of high-grade cancer. It is also noted that the average blood level of DHA was generally ‘low’ which is typical of American men who consume an average of one fish serving every 7-10 days (favourite type being tuna, a fish with much lower levels of DHA and EPA than salmon and many other fish and much lower than many fish oil supplements). Thus , the range of DHA levels in the blood went from ‘lower to higher’ with the ‘higher’ in fact being very much lower as compared to those who would consume fish (especially salmon, others) at least 2-3 times/week or take fish oil supplements containing DHA/EPA on a regular basis. Further, the blood levels of DHA were very much lower across the board than the Japanese who consume several levels of fatty fish/seafood/week.

4) It is noted that when 2-3 fatty fish servings/week or more or supplements containing fish oil are consumed, a significant rise in the blood levels of both DHA and EPA are seen . This is expected since both DHA plus EPA are found in fish and fish oil supplements. The EPA blood levels were very low in this study (typical of North Americans) who eat little fish . Further, the authors found no statistically-significant relation between blood levels of EPA or (EPA plus DHA) and the risk of high-grade prostate cancer. An earlier study (from Harvard) found no relation between blood levels of marine-derived omega-3 fatty acids ands prostate cancer risk (Gann et al., J. Nat. Cancer Inst., 86: 281-286(1994).

5) It is noted that a very recent paper from this same group (Brasky et al., Nutr. And Cancer, 63: 573-582 (2011) reported no relation between the intake of fish oil supplements and prostate cancer risk.

6) While the bulk of the published literature on higher fish intakes and higher (DHA plus EPA) intakes from fish/seafood or supplements show protective effects or no harm wrt prostate cancer , it is ‘possible’ that at very low DHA intakes and very low EPA intakes (ie, the lowest sub-set of American men when compared to the higher with the realization that essentially all are low by a global perspective), blood DHA levels (when moderately elevated ) may be a risk for advanced prostate cancer when the EPA levels remain low. Based on the literature in bulk, this is not likely with higher dietary intakes of DHA plus EPA and correspondingly higher blood levels of DHA plus EPA than found currently in American men (as in this study).

Finally, a major US analyses from various institutions which collaborated in the data analyses on lifestyle factors related to mortality concluded that low intakes of DHA plus EPA omega-3 from marine sources and high intakes of trans fatty acids were major risk factors for all-cause mortality (PLoS Med., 6: 1-23 (2009).).

Fish, Shellfish, and Long-Chain n-3 Fatty Acid Consumption and Risk of Incident Type 2 Diabetes in Middle-aged Chinese Men and Women

Villegas, R. et al., Amer. J. Clin. Nutr., in press , 2011

Summary :

This prospective population-based study included 64,193 women and 51,963 men from Shanghai, China who were free at baseline of type 2 diabetes, cardiovascular disease, and cancer. Dietary assessments of their intakes of fish/shellfish and long-chain omega-3 fatty acids (as DHA plus EPA) were determined. Follow-ups and statistical information were collected for a total follow-up time of 8.9 years for the women (SWHS-Shanghai Women’s Health Study) and 4.1 years for the men (SMHS).

The median daily intakes for fish and shellfish were 31.6 gm and 7.7 gm , respectively, for the women. A significant inverse relation between the intake levels of fish and shellfish and the risk of type 2 diabetes was found for the women such that those in the top 20 % with respect to intakes (median of 99.1 gms/day ) had a 14-17 % lower risk of disease development as compared to those (lowest intakes) with median intakes of only 13.6 gms/day when adjusting for other confounding factors. In the men, the lower apparent risk for disease development at the higher intakes did not reach statistical significance. In the women (SWHS) , higher intakes of (DHA plus EPA) were correlated with lower risks for disease development with the highest consumers (median intakes of 200 mg /day) exhibiting a 16-18 % lower risk for disease as compared to those with median intakes of only 20 mg/day. The authors stated that the inverse relations they found in women for fish/shellfish intakes (including the omega-3 fatty acids ) were also not associated with any deleterious effects.

Dr. Holub’s Comments :

Those women with the highest intakes (top 20 % of the population) of fish/shellfish in this population study had median intakes of 99.1 gms/day or the equivalent 7 fish servings/week (based on one serving weighing 100 gms or 3.5 ounces). Such intake levels of fish are very rare in North America , Europe, and numerous other countries. As example, North Americans average approx. one fish serving/week. However, it is noted that the highest median intakes of (DHA plus EPA) reported in the present study (SWHS) were 200 mg/day which is much less than expected if the 7 fish servings/week had been typical of the more popular fish as consumed in North America (eg., salmon, others). In this regard, it is noted that carp (including silver and grass carp) are popular in China as are tilapia and these contain much lower amounts of DHA plus EPA per serving than salmon . Current intakes per person of DHA plus EPA in North America from fish/seafood are approx. 130 mg/day.

Neurophysiologic and Neurobehavioral Evidence of Beneficial Effects of Prenatal Omega-3 Fatty Acid Intake on Memory Function at School Age

Boucher, O. et al., Amer. J. Clin. Nutr., 93: 1025-1037 , 2011

Laval University , Quebec, QC (Canada) and Wayne State University , Detroit, MI (USA)

Summary :

The primary purpose of the present study was to examine the relationship between omega-3 fatty acid status as estimated around the time of birth and subsequent memory function in school-age children in a fish-eating community. The study participants were school-aged Inuit children from the Nunavik region of Arctic Quebec(average age of 11 years, 58 % females). For these children, measurements were available on the levels of omega-3 fatty acids including DHA (docosahexaenoic acid) in their cord blood as obtained from the umbilical cord at birth. The children were subjected to well-established neurobehavioral assessments of memory including intelligences scales and verbal learning testing.

Those children who showed higher cord blood levels of DHA omega-3 at birth exhibited a positive association with better performances on the memory assessments. The authors also reported upon the possible adverse effects of prenatal (before birth) exposure to mercury and PCB on memory. The authors stated that the ‘current study was the first to document benefits of prenatal DHA intake on memory function in school-age children’.

Dr. Holub’s Comments :

The present study indicates that the higher intakes of DHA omega-3 fatty acid from pregnant women in fish- and seafood-eating populations and higher prenatal availability of DHA to the baby ‘in utero’ can have important beneficial effects for memory processing in their offspring up to 11 years later. The consumption of food sources rich in DHA omega-3 (and also EPA omega-3) should be encouraged during both pregnancy and childhood to support the optimization of cognitive performance. Furthermore, caution should be taken in selecting such foods to ensure protection against the ingestion of pollutants which may illicit any adverse effects.