Seafood Choices Balancing Benefits and Risks (2007) / Chapter Skim
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3 Health Benefits Associated with Nutrients in Seafood
3 Health Benefits Associated with Nutrients in Seafood
Pages 67-120
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From page 67... ...
In cases where benefits were not supported or were poorly supported by the literature, a statement is made to that effect. Scientific evidence to support benefits associated with seafood intake on cardiovascular risk reduction through prevention of disease development consists mainly of observational studies of seafood consumption among the general population.
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From page 68... ...
. In addition, seafood is an important contributor of selenium to the American diet and is unique among animal protein foods as a rich source for the omega-3 fatty acids EPA and DHA, although the roles of these fatty acids in maintaining health and preventing certain chronic diseases have not been completely elucidated (IOM, 2002/2005)
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From page 69... ...
Nutritional Benefits Associated with Omega-3 Fatty Acids Optimal Intake Leels for EPA and DhA There are insufficient data on the distribution of requirements to set an Estimated Average Requirement (EAR) for alpha-linolenic acid (ALA)
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From page 70... ...
Additionally, substitution of seafood for other food sources may decrease exposure to nutrients that are shown to increase health risks, such as saturated fats. On the other hand, some contaminants or toxins present in seafood may decrease or negate the benefit of EPA/DHA, as illustrated by the dilemma in making recommendations for seafood consumption in pregnant women, considering the potential benefits of EPA/DHA compared to potential risks of methylmercury exposure to the fetus.
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From page 71... ...
To date, however, there have been no randomized controlled trials or controlled clinical studies testing whether increased omega-3 fatty acid intake by pregnant women could reduce the risk for postpartum depression. Hibbeln (2002)
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From page 72... ...
(2003) investigated the relationship between postpartum depression and changes in maternal plasma phospholipid-associated fatty acid (DHA and docosapentaenoic acid [DPA]
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From page 73... ...
BENEFITS TO INFANTS AND CHILDREN ASSOCIATED WITH PRENATAL OMEGA-3 FATTY ACID INTAKE Transfer of Maternal DHA to the Fetus or Breastfeeding Infant The level of maternal DHA intake influences DHA levels in both maternal blood and milk. Blood DHA levels increase by about 50 percent in pregnancy (Al et al., 1995)
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From page 74... ...
have tested for an association between dietary supplementation with fish oil or the omega-3 fatty acids from fish oil (i.e., either DHA alone or EPA and DHA) and longer duration gestation.
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From page 75... ...
(1991) examined whether there was a difference in the ratio of the long-chain polyunsaturated fatty acids (LCPUFA)
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From page 76... ...
compared to levels from infants in southern Québec. Despite the association of seafood intake with environmental contaminants, however, the Nunavik women whose infants were in the third compared to the first tertile of percentage of omega-3 fatty acid out of total highly unsaturated fatty acid (HUFA)
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From page 77... ...
(1995) found that maternal essential fatty acid status progressively declines during pregnancy.
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From page 78... ...
The first experimental studies that provided DHA, AA, and EPA to preterm infants demonstrated an increase in blood lipid content of these fatty acids as well as increases in visual acuity (Uauy et al., 1990; Carlson et al., 1993)
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From page 79... ...
Blood and plasma fatty acid status were determined at 2 months; visual acuity at 2, 4, 6, and 12 months; and speech perception and object search at 9 months. Maternal milk DHA content was measured as an indicator of maternal DHA status, and this was linked with higher visual acuity (p<0.01)
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From page 80... ...
, examined associations of maternal fish intake during pregnancy and maternal hair mercury at delivery with infant cognition in a subset for which these data
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From page 81... ...
hEALTh BENEFITS ASSOCIATED WITh NUTRIENTS IN SEAFOOD BOX 3-1 Longitudinal Studies of Beneficial Outcomes to Women and Children from Seafood Consumption Project Viva Project Viva is a longitudinal study of women and their children, inves tigating the "effects of mother's diet and other factors during pregnancy on her health and the health of her child." From 1999 to 2002, more than 2600 pregnant women were enrolled from eight different Harvard Vanguard Medical Associate sites in the greater Boston area. Participating expectant mothers completed stan dardized interviews (on diet, exercise, medical history, stress, societal factors, and financial support)
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From page 82... ...
. VRM scores were highest among infants of women who consumed more than 2 servings of fish per week and had hair mercury levels less than or equal to 1.2 ppm.
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From page 83... ...
In this cohort, mercury levels were low and not associated with measures of neurodevelopment. Similar findings of association between maternal DHA status and more mature attentional development in infancy (Willatts et al., 2003b; Colombo et al., 2004)
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From page 84... ...
. These findings do not provide strong support for the hypothesis that exposure to omega-3 fatty acids from fish oil in utero or through breast milk could decrease the incidence of wheezing and atopic disease in early childhood (see Appendix Table B-1e)
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From page 85... ...
A Cochrane systematic review of nine randomized controlled trials, however, concluded that there was no association between DHA supplementation and increased visual acuity or general development in term infants (Simmer, 2005) (see Appendix B-1f)
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From page 86... ...
(2005) in a randomized controlled trial found significant increases in both the Bayley MDI and PDI in preterm infants given DHA- and AAsupplemented formula (p<0.05)
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From page 87... ...
(2001) found, in a randomized controlled trial among term infants, significantly higher vocabulary production in those fed DHA and AA from fish and fungal sources compared to DHA and AA from egg triglyceride (p<0.05)
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From page 88... ...
In addition, some positive effects have been found on cognitive function in infancy and childhood in both experimental and observational studies and in relation to both pre- and postnatal DHA intake. Reviews that take into account all lines of evidence have concluded that omega-3 fatty acids can be beneficial to cognitive development (Cohen et al., 2005; McCann and Ames, 2005)
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From page 89... ...
It is a good source of protein, and relative to other protein foods, e.g., meat, poultry, and eggs, is generally lower in saturated fatty acids and higher in the omega-3 fatty acids EPA and DHA as well as selenium; 2. The evidence to support benefits to pregnancy outcome in females who consume seafood or fish-oil supplements as part of their diet during pregnancy is derived largely from observational studies.
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From page 90... ...
a. Visual acuity has been measured in the most trials and is increased by DHA supplementation, with preterm infants more likely to benefit than term infants.
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From page 91... ...
As a result of this and related studies, seafood consumption, including or even especially of seafood rich in fat, has received increased attention as a public health means to decrease the burden of cardiovascular disease. Several observational studies have shown an inverse association between seafood consumption and the risk of cardiovascular disease, most probably due to reductions of sudden death (reviewed in Wang et al., 2006)
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From page 92... ...
Seafood or Omega-3 Fatty Acid Consumption and Coronary Heart Disease Randomized Controlled Trials in high Risk Populations No randomized controlled trials have been carried out on subjects representative of the general population, as the small expected number of
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From page 93... ...
(2003) reported higher, and not lower, cardiovascular mortality in the group assigned to receive advice to consume seafood or n-3 fatty acid supplements (p=0.02)
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In addition to the randomized clinical trials described above, another commonly cited study in support of the benefits of fish oil consumption comes from the Indian Study on Infarct Survival. This was reported by Singh et al.
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From page 95... ...
In this meta-analysis, all studies identified of primary prevention, i.e., incidence of CHD in people without a history of CHD, were observational studies that assessed seafood intake, while all studies of secondary prevention, i.e., in people with a history of CHD, were randomized trials using EPA/DHA supplements at doses difficult to achieve with seafood consumption. The authors of this meta-analysis were able to provide a
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From page 96... ...
Meta-analyses are usually considered stronger evidence than systematic reviews. Taken together, these meta-analyses of observational studies suggest a negative association between seafood consumption and CHD or death, particularly in individuals without a prior history of CHD.
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From page 97... ...
Although a decrease of 12 percent in the risk of both ischemic and hemorrhagic strokes was observed with a small amount of seafood consumption compared to no seafood consumption, this result was not statistically significant (95%CI: increased risk of 1 percent to decreased risk of 25 percent)
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From page 98... ...
In a subset of this population, consumption of tuna or other broiled or baked seafood, but not fried seafood or fish sandwiches (fish burgers) , correlated with plasma phospholipid long-chain omega-3 fatty acid levels.
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From page 99... ...
used seafood-based diets as part of the intervention protocol, and neither of them reported significant effects of seafood consumption on total cholesterol levels. Further, Mori et al.
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From page 100... ...
Body mass index, trial duration, and seafood dose did not affect the blood pressure response noted with fish-oil supplementation. Studies conducted in diabetic patients were not included in the meta-analysis.
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From page 101... ...
No association was found between phospholipid content of EPA/DHA and blood pressure in this population of high seafood consumers. It is unclear from these studies whether seafood consumption, in the range consumed by most Americans, is an effective means to reduce blood pressure (see Appendix Table B-2d)
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From page 102... ...
. In conclusion, there was no association between n-3 fatty acid intake from fish and a reduction in risk of atrial fibrillation or flutter.
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From page 103... ...
. No significant association was found for EPA/DHA impairment of platelet aggregation, although algal DHA oil is less potent than either fish oil or seafood (which are sources of both EPA and DHA)
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From page 104... ...
. Aging and Other Neurological Outcomes Consumption of EPA/DHA, specifically from seafood consumption, may provide some protection in terms of age-related cognitive decline as well as risk for Alzheimer's and other neurological diseases (Kalmijn et al., 1997; Gharirian et al., 1998; Barberger-Gateau et al., 2002; Morris et al., 2003)
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From page 105... ...
Contradictory • Blood pressure • Cardiovascular mortality and evidence or • Stroke events insufficient evidence • Allergy and asthma • Arrhythmia on which to base • Cancer • Cancer recommendations • Alzheimer's disease • Alzheimer's disease • Glycemic control in • Glycemic control in type II type II diabetes diabetes • Allergy and asthma • Preeclampsia • Postpartum depression • HDL, LDL, Lp(a) levels aUnlessotherwise noted.
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From page 106... ...
6. Evidence for a benefit associated with seafood consumption or fishoil supplements on blood pressure, stroke, cancer, asthma, type II diabetes, or Alzheimer's disease is inconclusive.
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From page 107... ...
This should include: • Evaluating preschool and school-age children exposed to EPA/ DHA in utero and postnatally, at ages beginning around 4 years when executive function is more developed, and;
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1995. Maternal essential fatty acid patterns during normal pregnancy and their relationship to the neonatal essential fatty acid status.
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2002. A random ized controlled trial of long-chain polyunsaturated fatty acid supplementation of formula in term infants after weaning at 6 wk of age.
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1997. Long chain polyunsaturated fatty acid supplementation of preterm infants.
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From page 111... ...
fish-oil n-3 fatty acids in mildly hyperlipidemic males. American Journal of Clinical Nutrition 53(5)
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2004. Randomized, double-blind trial of long-chain polyunsaturated fatty acid supplementation with fish oil and borage oil in preterm infants.
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2001. Randomized trials with polyunsaturated fatty acid interventions in preterm and term infants: Functional and clinical outcomes.
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2001. Are human milk long-chain polyunsaturated fatty acids related to visual and neural development in breast-fed term infants?
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2003. Clinical prevention of sudden cardiac death by n-3 polyunsaturated fatty acids and mechanism of prevention of arrhythmias by n-3 fish oils.
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Effects of varying dietary fat, fish and fish oils on blood lipids in a randomized controlled trial in men at risk of heart disease. American Journal of Clinical Nutrition 59(5)
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From page 117... ...
2001. Growth and development in preterm infants fed long-chain polyunsaturated fatty acids: A prospective, randomized controlled trial.
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2000b. Meta-analysis of dietary essential fatty acids and long-chain polyunsaturated fatty acids as they relate to visual resolution acuity in healthy preterm infants.
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2002. Dietary supplementation of long-chain polyunsaturated fatty acids in preterm infants: Effects on cerebral maturation.
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1998b. Influence of long-chain polyunsaturated fatty acids on infant cognitive function.
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