Measurement of mercury levels in concentrated over-the-counter fish oil preparations: is fish oil healthier than fish?

Mercury Exposure from the Consumption of Dietary Supplements Containing Vegetable, Cod Liver, and Shark Liver Oils

Vegetable and fish oils constitute a significant part of all dietary supplements. Due to increasing environmental pollution, the raw materials used for their production may be contaminated with toxic substances, including metals. The aim of the present study was to determine the mercury (Hg) content in vegetable oils, shark liver oils, and cod liver oils. The tests conducted were to help determine the level of mercury contamination of the tested preparations and the related potential threat to human health. The amount of Hg in the tested dietary supplements was compared, and the amount of the metal consumed at various times of use was determined. A total of 36 preparations of dietary supplements available on the Polish market were used for the study. The method of atomic absorption spectrometry using the amalgamation technique was used for the determinations (AMA 254, Altec, Czech Republic). Among the sample of all of the tested preparations, the Hg concentration ranged from 0.023 to 0.427 µg/kg, with an average of 0.165 µg/kg. Differences in Hg content in the various tested preparations (shark liver oil, cod liver oil, and vegetable oils) were statistically significant. The average concentration of Hg in the vegetable oils (0.218 µg/kg) was more than twice that of the cod liver oils (0.106 µg/kg) and shark liver oils (0.065 µg/kg). In none of the tested preparations did the amount of Hg exceed the acceptable standard for dietary supplements (0.10 mg/kg). The analysis showed that the Hg content in vegetable oils, shark liver oils, and fish oils from the Polish market is at a low level, guaranteeing the safety of their use, and as such, they do not pose a threat to health.

Fish Oil for Healthy Aging: Potential Application to Master Athletes

Master athletes perform high volumes of exercise training yet display lower levels of physical functioning and exercise performance when compared with younger athletes. Several reports in the clinical literature show that long chain n-3 polyunsaturated fatty acid (LC n-3 PUFA) ingestion promotes skeletal muscle anabolism and strength in untrained older persons. There is also evidence that LC n-3 PUFA ingestion improves indices of muscle recovery following damaging exercise in younger persons. These findings suggest that LC n-3 PUFA intake could have an ergogenic effect in master athletes. However, the beneficial effect of LC n-3 PUFA intake on skeletal muscle in response to exercise training in both older and younger persons is inconsistent and, in some cases, generated from low-quality studies or those with a high risk of bias. Other factors such as the choice of placebo and health status of participants also confound interpretation of existing reports. As such, when considered on balance, the available evidence does not indicate that ingestion of LC n-3 PUFAs above current population recommendations (250–500 mg/day; 2 portions of oily fish per week) enhances exercise performance or recovery from exercise training in master athletes. Further work is now needed related to how the dose, duration, and co-ingestion of LC n-3 PUFAs with other nutrients such as amino acids impact the adaptive response to exercise training. This work should also consider how LC n-3 PUFA supplementation may differentially alter the lipid profile of cellular membranes of key regulatory sites such as the sarcolemma, mitochondria, and sarcoplasmic reticulum.

Fatty acids: facts vs. fiction

During the last 100 years official dietary guidelines have recommended an increased consumption of fats derived from seeds while decreasing the consumption of traditional fats, especially saturated fats. These recommendations are being challenged by recent studies. Furthermore, the increased use of refining processes in fat production had deleterious health effects. Today, the number of high-quality studies on fatty acids is large enough to make useful recommendations on clinical application and everyday practice. Saturated fats have many beneficial functions and palmitic acid appears to be problematic only when it is synthesized due to excess fructose consumption. Trans fatty acids were shown to be harmful when they are manmade but beneficial when of natural origin. Conjugated linoleic acid has many benefits but the isomer mix that is available in supplement form differs from its natural origin and may better be avoided. The ω3 fatty acid linolenic acid has rather limited use as an anti-inflammatory agent - a fact that is frequently overlooked. On the other hand, the targeted use of long chain ω3 fatty acids based on blood analysis has great potential to supplement or even be an alternative to various pharmacological therapies. At the same time ω6 fatty acids like linoleic acid and arachidonic acid have important physiological functions and should not be avoided but their consumption needs to be balanced with long chain ω3 fatty acids. The quality and quantity of these fats together with appropriate antioxidative protection are critical for their positive health effects.

Determination of Total Mercury and Methylmercury Concentrations in Commercial Canine Diets

Methylmercury is an organic form of mercury that is well recognized for its bioaccumulation in aquatic species. Consumption of fish contaminated with methylmercury poses a toxicological health risk to both humans and animals. Salmon is an increasingly common ingredient in commercial pet foods because of manufacturers' interest in unconventional protein sources and inclusion of omega-3 polyunsaturated fatty acids. Previous studies have measured total mercury, but not methylmercury, in commercial pet foods. The purpose of this study was to evaluate total mercury and methylmercury concentrations in commercially available salmon-containing and nonsalmon-containing canine diets and to estimate risk of chronic exposure in dogs fed these diets long term. Total mercury was detected in 3 of 24 diets evaluated (12.5%), 2 of which did not contain any ingredients from fish. The single salmon-containing diet that contained total mercury was the lowest of the 3 but was also the only sample positive for methylmercury. None of the 3 mercury-containing diets contained fish oil. Concentrations of total mercury were similar to most data previously reported for pet foods. Using expected calorie intake for dogs of 2 body weights, the mercury concentrations determined in this study were applied to theoretical chronic exposure calculations to assess risk of toxicosis to dogs. Total mercury and methylmercury were uncommonly identified in the commercially available canine diets sampled in this study and were found in concentrations unlikely to pose risk to healthy adult dogs. Common sources of mercury in pet foods remain unknown and are not reliably of seafood origin.

A Randomized Multicenter Phase II Study of Docosahexaenoic Acid in Patients with a History of Breast Cancer, Premalignant Lesions, or Benign Breast Disease

Obesity, a cause of subclinical inflammation, is a risk factor for the development of postmenopausal breast cancer and is associated with poorer cancer outcomes. Docosahexaenoic acid (DHA), an omega-3 fatty acid, possesses anti-inflammatory properties. We hypothesized that treatment with DHA would reduce the expression of proinflammatory genes and aromatase, the rate-limiting enzyme for estrogen biosynthesis, in benign breast tissue of overweight/obese women. A randomized, placebo-controlled, double-blind phase II study of DHA given for 12 weeks to overweight/obese women with a history of stage I-III breast cancer, DCIS/LCIS, Paget's disease, or proliferative benign breast disease was carried out. In this placebo controlled trial, the primary objective was to determine whether DHA (1,000 mg by mouth twice daily) reduced breast tissue levels of TNFα. Secondary objectives included evaluation of the effect of DHA on breast tissue levels of COX-2, IL1β, aromatase, white adipose tissue inflammation, and gene expression by RNA-seq. Red blood cell fatty acid levels were measured to assess compliance. From July 2013 to November 2015, 64 participants were randomized and treated on trial (32 women per arm). Increased levels of omega-3 fatty acids in red blood cells were detected following treatment with DHA (P < 0.001) but not placebo. Treatment with DHA did not alter levels of TNFα (P = 0.71), or other biomarkers including the transcriptome in breast samples. Treatment with DHA was overall well-tolerated. Although compliance was confirmed, we did not observe changes in the levels of prespecified biomarkers in the breast after treatment with DHA when compared with placebo. Cancer Prev Res; 11(4); 203-14. ©2018 AACRSee related editorial by Fabian and Kimler, p. 187.

Metal and metalloid concentrations in the tissues of dusky Carcharhinus obscurus, sandbar C. plumbeus and white Carcharodon carcharias sharks from south-eastern Australian waters, and the implications for human consumption

Shark fisheries have expanded due to increased demand for shark products. As long-lived apex predators, sharks are susceptible to bioaccumulation of metals and metalloids, and biomagnification of some such as Hg, primarily through diet. This may have negative health implications for human consumers. Concentrations of Hg, As, Cd, Cu, Fe, Se and Zn were analysed in muscle, liver and fin fibres (ceratotrichia) from dusky Carcharhinus obscurus, sandbar Carcharhinus plumbeus, and white Carcharodon carcharias sharks from south-eastern Australian waters. Concentrations of analytes were generally higher in liver than in muscle and lowest in fin fibres. Muscle tissue concentrations of Hg were significantly correlated with total length, and >50% of sampled individuals had concentrations above Food Standards Australia New Zealand's maximum limit (1 mg kg(-1) ww). Arsenic concentrations were also of concern, particularly in fins. Results warrant further investigation to accurately assess health risks for regular consumption of shark products.

Effect of supercritical fluid extraction on the reduction of toxic elements in fish oil compared with other extraction methods

High-quality fish oil for human consumption requires low levels of toxic elements. The aim of this study was to compare different oil extraction methods to identify the most efficient method for extracting fish oil of high quality with the least contamination. The methods used in this study were Soxhlet extraction, enzymatic extraction, wet reduction, and supercritical fluid extraction. The results showed that toxic elements in fish oil could be reduced using supercritical CO2 at a modest temperature (60°C) and pressure (35 MPa) with little reduction in the oil yield. There were significant reductions in mercury (85 to 100%), cadmium (97 to 100%), and lead (100%) content of the fish oil extracted using the supercritical fluid extraction method. The fish oil extracted using conventional methods contained toxic elements at levels much higher than the accepted limits of 0.1 μg/g.

Optimisation of the supercritical extraction of toxic elements in fish oil

This study aims to optimise the operating conditions for the supercritical fluid extraction (SFE) of toxic elements from fish oil. The SFE operating parameters of pressure, temperature, CO2 flow rate and extraction time were optimised using a central composite design (CCD) of response surface methodology (RSM). High coefficients of determination (R²) (0.897-0.988) for the predicted response surface models confirmed a satisfactory adjustment of the polynomial regression models with the operation conditions. The results showed that the linear and quadratic terms of pressure and temperature were the most significant (p < 0.05) variables affecting the overall responses. The optimum conditions for the simultaneous elimination of toxic elements comprised a pressure of 61 MPa, a temperature of 39.8ºC, a CO₂ flow rate of 3.7 ml min⁻¹ and an extraction time of 4 h. These optimised SFE conditions were able to produce fish oil with the contents of lead, cadmium, arsenic and mercury reduced by up to 98.3%, 96.1%, 94.9% and 93.7%, respectively. The fish oil extracted under the optimised SFE operating conditions was of good quality in terms of its fatty acid constituents.

Long-chain omega-3 fatty acids: time to establish a dietary reference intake

The beneficial effects of consuming omega-3 polyunsaturated fatty acids (n-3 PUFAs), specifically eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), on cardiovascular health have been studied extensively. To date, there is no dietary reference intake (DRI) for EPA and DHA, although many international authorities and expert groups have issued dietary recommendations for them. Given the substantial new evidence published since the last Institute of Medicine (IOM) report on energy and macronutrients, released in 2002, there is a pressing need to establish a DRI for EPA and DHA. In order to set a DRI, however, more information is needed to define the intakes of EPA and DHA required to reduce the burden of chronic disease. Information about potential gender- or race-based differences in requirements is also needed. Given the many health benefits of EPA and DHA that have been described since the 2002 IOM report, there is now a strong justification for establishing a DRI for these fatty acids.

Omega-3 fatty acids and ginger in maternal health: pharmacology, efficacy, and safety

Dietary supplements may be used by pregnant women if they perceive them to be natural and healthy products, if they are fearful of using prescription drugs, or if they are recommended by a health care provider. Usage surveys indicate that midwives feel comfortable in recommending some herbal products to their patients. There are sufficient data from randomized controlled trials on omega-3 fatty acids and ginger that their pharmacologic properties, efficacy, and safety data for specific indications in maternal health can be evaluated. Requests for information regarding these substances are likely to be encountered by health care providers who care for pregnant women. Omega-3 fatty acids benefit gestation, infant vision, and neurodevelopment, while effects on major depression in pregnancy and postpartum depression are less clear. Ginger is efficacious for nausea and vomiting in pregnancy but is limited in its safety data. Pharmacologic properties of each supplement and pathophysiology related to each indication are reviewed. It is recommended that pregnant and lactating women be advised to take an omega-3 fatty acid supplement daily, while the recommendation to use ginger is tentative and will likely be based on each practitioner's comfort level with the safety data that are presented.

Integrative care of the mother-infant dyad

There are many options for natural and preventative therapies during pregnancy and childbirth, which may aid in minimizing the use of pharmaceuticals and invasive procedures. Patients may seek these out, and it is important for physicians to have some basic knowledge to guide their choices. Of all therapies, the most important are nutrition for optimizing health and the provision of continuous support during labor.

Perspectives on the use of marine and freshwater hydrobiont oils for development of drug delivery systems

Marine foods represent a unique source of poly-unsaturated fatty acids (PUFA) of the omega-3 (n-3) family. Today it is generally accepted that fish oil is important in a healthy and balanced omnivorous human diet. This favorable health perception of fish oil is however troubled by the high level of PUFA oxidation and low absorption in the gastro-intestinal tract. In this work we present and described various types of delivery systems which are used to improve PUFA and fish oil availability and oxidative stability.

Prevention of age-related macular degeneration

Age-related macular degeneration (AMD) is one of the leading causes of blindness in the developed world. Although effective treatment modalities such as anti-VEGF treatment have been developed for neovascular AMD, there is still no effective treatment for geographical atrophy, and therefore the most cost-effective management of AMD is to start with prevention. This review looks at current evidence on preventive measures targeted at AMD. Modalities reviewed include (1) nutritional supplements such as the Age-Related Eye Disease Study (AREDS) formula, lutein and zeaxanthin, omega-3 fatty acid, and berry extracts, (2) lifestyle modifications, including smoking and body-mass-index, and (3) filtering sunlight, i.e. sunglasses and blue-blocking intraocular lenses. In summary, the only proven effective preventive measures are stopping smoking and the AREDS formula.

Mercury concentrations and omega-3 fatty acids in fish and shrimp: Preferential consumption for maximum health benefits

The consumption of fish and shrimp containing omega-3 fatty acids can result in protective health effects including a reduced risk of cardiovascular disease, stroke, and diabetes. These protective effects may be decreased by the presence of mercury in the muscle tissue of fish and shellfish. Mercury can increase the risk of cardiovascular problems and impede neurological development. The objective of this project was to determine appropriate consumption amounts of selected fish species and shrimp based on mercury levels and recommended intake levels of omega-3 fatty acids. Species that are high in omega-3s and low in mercury include salmon, trout, and shrimp. Species with both high levels of mercury and omega-3 fatty acids include tuna, shark, and halibut, swordfish, and sea bass.

Benefits versus risks associated with consumption of fish and other seafood

Fish provide nutrition for much of the world's population, and when not contaminated with chemicals, fish is a very good food. A major benefit of fish is that they are high in polyunsaturated fatty acids (PUFAs), low in saturated fat, and they contain other critical nutrients. Much of the benefit of fish consumption derives from their high levels of long chain omega-3 PUFAs, which are produced by aquatic microorganisms and bioconcentrate in the aquatic food supply. The PUFAs are essential, in that humans and other vertebrates are not able to synthesize them and therefore must obtain them from the diet. The PUFAs particularly concentrate in the nervous system, alter immune system function reduce serum triglyceride levels and have been reported to reduce the risk of sudden death after a myocardial infarction. But the problem is that most fish have at least some degree of chemical contamination with methylmercury, (which binds to muscle) and/or with persistent organic pollutants such as dioxins, polychlorinated biphenyls, polybrominated diphenyl ethers, chlorinated pesticides (which concentrate in fish fat). These chemicals have adverse effects on nervous system function, modulate the immune system, and are associated with elevations in risk of cardiovascular disease. Thus the question of benefits and risk from fish consumption is complex but very important.

Complementary and alternative medicine for the treatment of depressive disorders in women

Complementary and alternative medicine (CAM) therapies are commonly practiced in the United States and are used more frequently among women than men. This article reviews several CAM treatments for depressive disorders in women, with a focus on major depressive disorder across the reproductive life cycle. The CAM therapies selected for this review (ie, S-adenosylmethionine, omega-3 fatty acids, St John's wort, bright light therapy, acupuncture, and exercise) were based on their prevalence of use and the availability of randomized, placebo-controlled data. Further study is necessary to delineate the role of specific CAM therapies in premenstrual syndrome, premenstrual dysphoric disorder, antepartum and postpartum depression, lactation, and the menopausal transition.

Omega-3 supplements in pregnancy: are we too late to identify the possible benefits?

OBJECTIVE

Postpartum depression (PPD) is a common and recurring illness. Most women who experience PPD do not seek professional help; for those who do, the available treatment options are not supported by extensive research evidence. Several lines of research have linked omega-3 fatty acids (omega-3) supplementation with a reduced risk of PPD. Although it has been suggested that women in the perinatal period consume sufficient omega-3 to potentially prevent PPD, there is a lack of definitive research evidence. This pilot study surveyed pregnant women's current use of omega-3, multivitamin, and other supplements, as well as their attitudes toward omega-3 research during pregnancy, to assess the feasibility of pregnant women's participation in a large randomized controlled trial evaluating omega-3 supplementation.

METHODS

Women attending prenatal clinics over a three-week period were invited to participate in a survey. The survey contained an information letter that was followed by a brief questionnaire assessing the use of nutritional supplements and opinions regarding the likelihood of participating in a clinical trial during pregnancy.

RESULTS

Of the 176 women who completed the survey, six women were in the first trimester of pregnancy, 82 were in the second trimester, and 87 were in the third trimester. One hundred fifty-nine respondents (90.3%) reported taking a multivitamin supplement but none were taking a supplement that contained omega-3; only 20 (11.4%) were taking omega-3. Seventy-eight women (44.4%) responded that they would participate in a clinical study evaluating the effects of fish oil on their health.

CONCLUSION

The results of our study indicate that many pregnant women take prenatal multivitamins and nutritional supplements, that there are currently few pregnant women attending clinics at our hospitals who are supplementing with omega-3, and that pregnant women would be willing to participate in a clinical trial evaluating the effects of omega-3.

Enhanced absorption of n-3 fatty acids from emulsified compared with encapsulated fish oil

Health benefits of n-3 fatty acids are well-established. However, consumption of adequate dietary sources of these fatty acids is inadequate. Oral fish oil supplements are an alternative means of consuming adequate long-chain n-3 fatty acids in individuals who do not consume sufficient dietary sources. However, palatability can present a problem with compliance. Emulsifying fish oil allows for production of a pleasant-tasting supplement and can enhance digestion and absorption of the fatty acids. We investigated the rate and extent of absorption of emulsified fish oil compared with capsular triglyceride fish oil supplements in humans. Participants subjectively rated palatability of these products. A randomized, crossover-designed, open-label trial was performed in which 10 healthy volunteers received emulsified fish oil and capsular triglyceride fish oil orally. Blood samples were collected at 0, 2, 4, 8, 24, and 48 hours to determine the absorption of individual fatty acids into plasma phospholipid fatty acids. At the completion of blood collection, subjects were asked to subjectively rate the tolerance and acceptability of the two supplements. During a 48-hour period, there was enhanced absorption of total n-3 and eicosapentaenoic acid (0.67%+/-0.16%, 0.45%+/-0.06%; P<0.01; 0.34%+/-0.05%, 0.23%+/-0.04%; P=0.05; emulsified fish oil and capsular triglyceride fish oil, respectively) observed for the emulsified fish oil treatment. Our findings indicate that a single dose of emulsified fish oil resulted in enhanced absorption of total n-3 eicosapentaenoic acid and docosahexaenoic acid as evidenced by changes in phospholipid fatty acids composition compared with the capsular triglyceride fish oil during the 48-hour observation period. Both supplements were subjectively rated and found to be well-tolerated by participants.

A systemic review of the roles of n-3 fatty acids in health and disease

Attention to the role of n-3 long-chain fatty acids in human health and disease has been continuously increased during recent decades. Many clinical and epidemiologic studies have shown positive roles for n-3 fatty acids in infant development; cancer; cardiovascular diseases; and more recently, in various mental illnesses, including depression, attention-deficit hyperactivity disorder, and dementia. These fatty acids are known to have pleiotropic effects, including effects against inflammation, platelet aggregation, hypertension, and hyperlipidemia. These beneficial effects may be mediated through several distinct mechanisms, including alterations in cell membrane composition and function, gene expression, or eicosanoid production. A number of authorities have recently recommended increases in intakes of n-3 fatty acids by the general population. To comply with this recommendation a variety of food products, most notably eggs, yogurt, milk, and spreads have been enriched with these fatty acids. Ongoing research will further determine the tissue distribution, biological effects, cost-effectiveness, and consumer acceptability of such enriched products. Furthermore, additional controlled clinical trials are needed to document whether long-term consumption or supplementation with eicosapentaenoic acid/docosahexaenoic acid or the plant-derived counterpart (alpha-linolenic acid) results in better quality of life.

Complementary and alternative medicine for perinatal depression

INTRODUCTION

Perinatal Major Depressive Disorder (MDD) is common and poses particular treatment dilemmas. Complementary and Alternative Medicine (CAM) treatments are widely used, accessible, and understudied for well-defined psychiatric indications. Women are more likely than men to both suffer from MDD and use CAM.

METHODS

A PubMed/Medline search was conducted to assess the evidence base for commonly utilized CAM treatments, MDD, and perinatal depression.

RESULTS

Among CAM treatments, omega-3 fatty acids have received the most specific study in terms of epidemiological, preclinical, and clinical research for perinatal depression. Three randomized placebo-controlled trials have been conducted in which investigators assessed omega-3 fatty acids vs. placebo for perinatal depression, with conflicting results. CAM interventions that can be easily added to a treatment plan with little risk and general health benefits for most women include omega-3 fatty acids, exercise, and folate, although data are insufficient at this time to recommend any of these as monotherapy for perinatal depression. S-adenosyl-methionine (SAMe) and bright light therapy may be reasonable to consider based on the evidence in MDD. St. John's Wort requires further study with regard to safety in pregnancy, and drug interactions can be a potential problem.

DISCUSSION

Further study is required to elucidate the role of CAM treatments for perinatal depression, and the clinical context of perinatal depression requires safe, effective, and accessible treatment options.

Omega-3 fatty acids and supportive psychotherapy for perinatal depression: a randomized placebo-controlled study

BACKGROUND

Perinatal major depressive disorder (MDD), including antenatal and postpartum depression, is common and has serious consequences. This study was designed to investigate the feasibility, safety, and efficacy of omega-3 fatty acids for perinatal depression in addition to supportive psychotherapy.

METHODS

Perinatal women with MDD were randomized to eicosapentaenoic (EPA) and docosahexaenoic acids (DHA), 1.9g/day, or placebo for 8weeks. A manualized supportive psychotherapy was provided to all subjects. Symptoms were assessed with the Hamilton Rating Scale for Depression (HAM-D) and Edinburgh Postnatal Depression Scale (EPDS) biweekly.

RESULTS

Fifty-nine women enrolled; N = 51 had two data collection points that allowed for evaluation of efficacy. Omega-3 fatty acids were well tolerated. Participants in both groups experienced significant decreases in EPDS and HAM-D scores (p<.0001) from baseline. We did not find a benefit of omega-3 fatty acids over placebo. Dietary omega-3 fatty acid intake was low among participants.

LIMITATIONS

The ability to detect an effect of omega-3 fatty acids may have been limited by sample size, study length, or dose. The benefits of supportive psychotherapy may have limited the ability to detect an effect of omega-3 fatty acids.

CONCLUSIONS

There was no significant difference between omega-3 fatty acids and placebo in this study in which all participants received supportive psychotherapy. The manualized supportive psychotherapy warrants further study. The low intake of dietary omega-3 fatty acids among participants is of concern, in consideration of the widely established health advantages in utero and in infants.

New approaches to therapy with omega-3 fatty acids

With greater focus on chronic disease prevention, renewed attention has been directed toward understanding the pathophysiology of various medical conditions and the development of newer medical treatments to prevent and treat complications. There has been immense interest in evaluating societal lifestyles, cultural attitudes toward health, and dietary influences on health conditions. The omega-3 fatty acids have become a focus of interest, and recent research and trial evidence have highlighted their effects, including potential clinical advantages. Despite this progress, the precise mechanisms through which omega-3 fatty acids act remain poorly understood. These agents are now recommended as secondary prevention after acute myocardial infarction, and ongoing large clinical trials should provide insight into the use of omega-3 fatty acids in heart failure and the primary prevention of cardiovascular disease.

Omega-3 fatty acids for cardioprotection

The most compelling evidence for the cardiovascular benefit provided by omega-3 fatty acids comes from 3 large controlled trials of 32,000 participants randomized to receive omega-3 fatty acid supplements containing docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) or to act as controls. These trials showed reductions in cardiovascular events of 19% to 45%. These findings suggest that intake of omega-3 fatty acids, whether from dietary sources or fish oil supplements, should be increased, especially in those with or at risk for coronary artery disease. Patients should consume both DHA and EPA. The target DHA and EPA consumption levels are about 1 g/d for those with known coronary artery disease and at least 500 mg/d for those without disease. Patients with hypertriglyceridemia benefit from treatment with 3 to 4 g/d of DHA and EPA, a dosage that lowers triglyceride levels by 20% to 50%. Although 2 meals of oily fish per week can provide 400 to 500 mg/d of DHA and EPA, secondary prevention patients and those with hypertriglyceridemia must use fish oil supplements if they are to reach 1 g/d and 3 to 4 g/d of DHA and EPA, respectively. Combination therapy with omega-3 fatty acids and a statin is a safe and effective way to improve lipid levels and cardiovascular prognosis beyond the benefits provided by statin therapy alone. Blood DHA and EPA levels could one day be used to identify patients with deficient levels and to individualize therapeutic recommendations.

Negative confounding in the evaluation of toxicity: the case of methylmercury in fish and seafood

In observational studies, the presence of confounding [corrected] can distort the true association between an exposure and a toxic-effect outcome, if the confounding variable is not controlled for in the study design or analysis phase. While confounding is often assumed to occur in the same direction as the toxicant exposure, the relationship between the benefits and risks associated with fish and seafood consumption is a classic example of negative confounding: the exposure to methylmercury occurs with fish and seafood, which are also associated with beneficial nutrients, and the signs of mercury toxicity [corrected] Mercury and nutrients may affect the same epidemiological outcomes, but most studies addressing one of them have ignored the potential for negative confounding by the other. This article reviews the existing evidence of effects of both nutrient and contaminant intakes as predictors of neurodevelopmental and cardiovascular outcomes. Substantial underestimation of the effects of mercury toxicity and of fish benefits occurs from the lack of confounder adjustment and imprecision of the exposure parameters. Given this inherent bias in observational studies, regulatory agencies should reconsider current dietary advice in order to provide better guidance to consumers in making prudent choices to maintain a nutritious diet with seafood that is low in mercury concentrations. Attention should also be paid to the occurrence of negative confounding in other connections.

Comparison of the effects of fish and fish-oil capsules on the n 3 fatty acid content of blood cells and plasma phospholipids

BACKGROUND

n-3 Fatty acids (FAs) have been shown to be beneficial for cardiovascular health. Whether n-3 FAs from oily fish consumed weekly or from fish-oil capsules taken daily are equally bioavailable is not clear.

OBJECTIVE

The purpose of this study was to compare the rate and extent of enrichment of blood cell membranes [ie, red blood cells (RBCs)] and plasma phospholipids with n-3 FAs from these 2 sources.

DESIGN

Healthy premenopausal female volunteers were randomly assigned to consume a daily average of 485 mg eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids either from 2 servings of oily fish (ie, salmon and albacore tuna) per week or from 1-2 capsules/d.

RESULTS

After 16 wk, EPA+DHA in RBCs in the fish group (n = 11) increased from 4.0 +/- 0.6% of total FAs to 6.2 +/- 1.4%, whereas it rose from 4.3 +/- 1.0% to 6.2 +/- 1.4% in the capsule group (P < 0.0001 for both; NS for group effect). Similar results were observed in plasma phospholipids. EPA+DHA stabilized in the latter after 4 wk but continued to rise through week 16 in RBCs. EPA in RBCs increased significantly (P = 0.01) more rapidly in the fish group than in the capsule group during the first 4 wk, but rates did not differ significantly between groups thereafter. Total FA variances were less in RBCs than in plasma phospholipids (P = 0.04).

CONCLUSION

These findings suggest that the consumption of equal amounts of EPA and DHA from oily fish on a weekly basis or from fish-oil capsules on a daily basis is equally effective at enriching blood lipids with n-3 FAs.

Tolerability of omega-3 fatty acid supplements in perinatal women

BACKGROUND

Benefits of omega-3 fatty acids in perinatal women are well documented, although fish intake has declined among perinatal women.

OBJECTIVE

To determine the tolerability of omega-3 fatty acid supplementation in perinatal women.

DESIGN

Pregnant and postpartum women with major depressive disorder (MDD) entered an 8-week double-blind, placebo-controlled trial of omega-3 fatty acids. Four capsules provided 1.84 g/day of eicosapentanoic acid (EPA) and docosahexaenoic acid (DHA), or matching placebo (corn oil with 1% fish oil to maintain blind). Tolerability was assessed by clinician interview biweekly.

RESULTS

Fifty-nine women enrolled. Thirteen (22%) reported mainly transient side effects including dizziness, diarrhea, nausea, burping, heartburn/reflux, difficulty swallowing capsules, unpleasant breath/bad taste or feeling tired. The most common were unpleasant breath/bad taste and heartburn/reflux. Six reporting side effects received omega-3 fatty acids; seven received placebo. Neither pregnant nor postpartum women discontinued due to intolerability.

CONCLUSIONS

Omega-3 fatty acid supplements were well tolerated by perinatal women.

Safety considerations with omega-3 fatty acid therapy

It has been suggested that the potential antithrombotic effect of fish oils may theoretically increase the risk for bleeding, which may be a safety concern for individual patients. However, clinical trial evidence has not supported increased bleeding with omega-3 fatty acid intake, even when combined with other agents that might also increase bleeding (such as aspirin and warfarin). Another potential safety concern is the susceptibility of omega-3 fatty acid preparations to undergo oxidation, which contributes to patient intolerance and potential toxicity. Finally, large amounts of fish consumption may result in adverse experiences due to the potential presence of environmental toxins such as mercury, polychlorinated biphenyls, dioxins, and other contaminants. The risks of exposure to environmental toxins and hypervitaminosis with fish consumption are substantially reduced through purification processes used to develop selected concentrated fish oil supplements and prescription preparations. Thus, in choosing which fish oil therapies to recommend, clinicians should be aware of available information to best assess their relative safety, which includes the US Food and Drug Administration (FDA) and Environmental Protection Agency (EPA) advisory statement regarding fish consumption, the meaning of certain labeling (such as "verification" through the US Pharmacopeia) and the differences in FDA regulatory requirements between nonprescription fish oil supplements and prescription fish oil preparations, and how all of this is important to the optimal treatment of patients.

Sources of the very-long-chain unsaturated omega-3 fatty acids: eicosapentaenoic acid and docosahexaenoic acid

PURPOSE OF REVIEW

We assess the toxicological, environmental and economic aspects of sources of fish oil and omega-3 fatty acids (n-3 fatty acids).

RECENT FINDINGS

Fish oils are the most common source of the very-long-chain n-3 fatty acids eicosapentaenoic acid and docosahexaenoic acid, which have protective and beneficial effects on conditions such as cardiovascular, inflammatory, or neurological diseases. Fish oils can also be potential hazards for human health, because of external pollutants bio-accumulating in fish. Wild and farmed fish are generally both similar in n-3 fatty acid content but may vary in terms of potential toxins. Reports on aquaculture and fish oil production, and other sources of n-3 fatty acids, are reviewed to assess which may be more suitable economically and ecologically for higher fish oil production and availability.

SUMMARY

Although today's fish oil production meets demand, it is likely that this will not be able to increase without adversely affecting the world's wild stock of fish. Neither wild nor farmed fish constitute a sustainable source of n-3 fatty acids for supplementation. Solutions may be found through the evolution of the current aquaculture system or the utilization of alternative manufacturing sources for increasing intakes of n-3 fatty acids.

Omega-3 fatty acids and perinatal depression: a review of the literature and recommendations for future research

INTRODUCTION

Perinatal depression refers to major depression in the context of pregnancy and postpartum. In consideration of its prevalence and consequences, the treatment and prevention of perinatal depression should be important public health priorities. Omega-3 fatty acids are attractive for consideration in perinatal women, due to known health benefits for the mother and baby. Antidepressant medications may pose risks in utero and in breastfeeding.

METHODS

MEDLINE and manual searches were conducted.

RESULTS

Epidemiological and preclinical data support a role of omega-3 fatty acids in perinatal depression. Two studies failed to support a role of omega-3 fatty acids for postpartum depression prophylaxis, although one included a small sample, and the other utilized a low dosage. Two pilot studies suggest good tolerability and potential efficacy in the acute treatment of perinatal depression.

CONCLUSIONS

Further research studies are warranted to determine the role of omega-3 fatty acids in the treatment of perinatal depression.

n-3 fatty acid dietary recommendations and food sources to achieve essentiality and cardiovascular benefits

Dietary recommendations have been made for n-3 fatty acids, including alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) to achieve nutrient adequacy and to prevent and treat cardiovascular disease. These recommendations are based on a large body of evidence from epidemiologic and controlled clinical studies. The n-3 fatty acid recommendation to achieve nutritional adequacy, defined as the amount necessary to prevent deficiency symptoms, is 0.6-1.2% of energy for ALA; up to 10% of this can be provided by EPA or DHA. To achieve recommended ALA intakes, food sources including flaxseed and flaxseed oil, walnuts and walnut oil, and canola oil are recommended. The evidence base supports a dietary recommendation of approximately 500 mg/d of EPA and DHA for cardiovascular disease risk reduction. For treatment of existing cardiovascular disease, 1 g/d is recommended. These recommendations have been embraced by many health agencies worldwide. A dietary strategy for achieving the 500-mg/d recommendation is to consume 2 fish meals per week (preferably fatty fish). Foods enriched with EPA and DHA or fish oil supplements are a suitable alternate to achieve recommended intakes and may be necessary to achieve intakes of 1 g/d.