Elsevier

Nutrition

Volume 26, Issue 2, February 2010, Pages 168-174
Nutrition

Applied nutritional investigation
Moderate consumption of fatty fish reduces diastolic blood pressure in overweight and obese European young adults during energy restriction

https://doi.org/10.1016/j.nut.2009.04.002Get rights and content

Abstract

Objective

Dietary intervention studies suggest that a daily fish meal can improve blood pressure (BP); however, such a dietary regimen might be difficult to sustain. The objective of the present study was to investigate whether salmon consumption three times per week improves BP during energy restriction in young adults.

Methods

In this 8-wk intervention, 324 subjects (20–40 y of age, body mass index 27.5–32.5 kg/m2, from Iceland, Spain, and Ireland) were randomized to one of four energy-restricted diets (−30% relative to estimated requirements): salmon (150 g three times per week, resulting in a daily consumption of 2.1 g of ω-3 long-chain polyunsaturated fatty acids [ω-3 LC-PUFAs]), cod (150 g three times per week, 0.3 g of ω-3 LC-PUFAs per day), fish oil capsules (1.3 g of ω-3 LC-PUFAs per day), or control (sunflower oil capsules, no seafood). Body weight, diastolic BP (DBP), systolic BP (SBP), and docosahexaenoic acid (DHA) in erythrocyte membrane were measured at baseline and endpoint.

Results

Participants showed weight loss (−5.2 ± 3.2 kg, P < 0.001) and decreases in SBP (−4.4 ± 8.6 mmHg, P < 0.001) and DBP (−4.1 ± 7.4 mmHg, P < 0.001) after the intervention. The salmon (B = −2.71, P = 0.032) and fish oil (B = −2.48, P = 0.044) groups had significantly lower endpoint DPB than the cod group, but not significantly different from control. Lower baseline DHA (percentage) in erythrocytes was associated with greater DBP reductions (B = 0.576, P = 0.017).

Conclusion

Salmon consumption three times per week can decrease DBP similar to fish oil and significantly more than lean fish during an 8-wk energy restriction in young overweight individuals. A lower DHA content in erythrocyte membrane at baseline, which might indentify infrequent fish eaters, is associated with a greater DBP reduction in the course of an 8-wk dietary intervention providing fatty seafood.

Introduction

Hypertension is one of the causes of cardiovascular disease [1]. Diet plays an important role in the etiology of hypertension, because obesity and nutrient intake are known to affect blood pressure (BP). The BP-lowering properties of ω-3 long-chain polyunsaturated fatty acids (ω-3 LC-PUFA) from fish oil supplements have been thoroughly investigated and confirmed [2], [3], [4], [5], with commonly used doses of 4–5 g of ω-3 LC-PUFAs per day leading to clinically significant reductions in BP. The largest effects are achieved in elderly hypertensives [4]. Several biological mechanisms have been suggested to explain the health benefits of ω-3 LC-PUFAs on BP, e.g., changes in phospholipid composition, platelet aggregation, and vasodilatation [6], [7], [8], [9], [10], [11].

Without the use of seafood supplements (fish oil or marine algae), a ω-3 LC-PUFAs intake of 4–5 g/d can hardly be achieved, even if one consumes a daily fish meal. There are relatively few dietary intervention trials that have investigated the effects of daily fish consumption (in contrast to fish oil ingestion) on BP, and some [12], [13] but not all [14], [15], [16] have found BP reduction by fatty fish consumption. Not daily, but still frequent fatty fish consumption, e.g., three times a week, usually provides a daily amount of 1–1.5 g of ω-3 LC-PUFAs and might be sustained easier by less committed seafood eaters than a daily fish meal. It is an important question whether such a dietary regimen can improve BP.

In the present analysis, which was a part of the SEAFOODplus YOUNG study, we investigated the effects of regular fatty fish consumption (salmon three times per week) in comparison with lean fish (cod three times per week), fish oil (daily) and a control without seafood, in combination with energy restriction, on BP in young overweight and obese adults. The reason for also investigating lean fish, which does not provide high amounts of ω-3 LC-PUFAs, is that there is some preliminary evidence from animal studies suggesting that fish protein might also have BP-lowering effects [17], [18]. We conducted a randomized, controlled dietary intervention trial in young overweight and obese, normo- and hypertensive individuals from three European countries. In terms of prevention, young adulthood might be a very critical time, with its changes in diet and physical activity linked with hypertension [19], [20]. Results from the SEAFOODplus YOUNG study, e.g., on weight loss, have been published elsewhere [21].

Section snippets

Subjects

A total of 324 overweight individuals (138 men and 186 women) were included in the SEAFOODplus YOUNG study (www.seafoodplus.org) through advertisements, 140 from Iceland, 120 from Spain, and 64 from Ireland. All subjects were screened for inclusion and exclusion criteria. The inclusion criteria were a body mass index ranging from 27.5 to 32.5 kg/m2, age 20–40 y, and waist circumferences ≥94 cm and ≥80 cm for men and women, respectively. Exclusion criteria were weight change (±3 kg) due to a

Results

The participants' baseline values are listed in Table 1. Of the male participants, 55.8% had hypertension, but only 15.6% of female participants did. Baseline docosahexaenoic acid (DHA) content in erythrocytes correlated with baseline DBP (ρ = −0.118, P = 0.050) and with frequency of fish consumption (ρ = 0.272, P < 0.001).

During the intervention (Table 2) the intakes of energy, carbohydrates, protein, fat, saturated fat, calcium, sodium, and potassium decreased significantly, with the highest

Discussion

In this study we investigated the effects of different diets on BP reduction during an 8-wk weight-loss diet in young overweight and obese European adults. Subjects in the four groups received salmon (fatty fish), cod (lean fish), fish oil capsules, or placebo capsules, but otherwise the same percentage energy restriction, and were recruited to diets prescribing identical macronutrient composition. During these 8 wk, mean body weight, SBP, and DBP decreased significantly in the participants.

Conclusions

Salmon consumption decreases DBP similar to fish oil consumption and more than lean fish consumption during an 8-wk diet in young overweight individuals. Lower DHA content in erythrocyte membrane at baseline, which might indentify infrequent fish eaters, is associated with greater DBP reduction during an 8-wk dietary intervention providing seafood.

Acknowledgments

Thanks are due to the European Union Commission for financial support and to the volunteers participating in the study.

References (31)

  • M.C. Morris et al.

    Does fish oil lower blood pressure? A meta-analysis of controlled trials

    Circulation

    (1993)
  • L.J. Appel et al.

    Does supplementation of diet with ‘fish oil’ reduce blood pressure?

    Arch Intern Med

    (1993)
  • J.M. Geleijnse et al.

    Blood pressure response to fish oil supplementation: Meta-regression analysis of randomized trials

    J Hypertens

    (2002)
  • M. Hashimoto et al.

    Effects of eicosapentaenoic acid and docosahexaenoic acid on plasma membrane fluidity of aortic endothelial cells

    Lipids

    (1999)
  • E.K. Lund et al.

    Effects of dietary fish oil supplementation on the phospholipid composition and fluidity of cell membranes from human volunteers

    Ann Nutr Metab

    (1999)
  • Cited by (66)

    • Consumption of fish and vascular risk factors: A systematic review and meta-analysis of intervention studies

      2017, Atherosclerosis
      Citation Excerpt :

      Ramel et al. observed that salmon consumption decreased diastolic blood pressure, similar to fish oil, and significantly more than lean fish. Among the most studied novel biomarkers are the inflammatory biomarkers and C-reactive protein (CRP) [6]. The use of novel biomarkers to increase standard risk algorithms has attracted increasing attention in recent years [7].

    • Fish and fish oil and the metabolic syndrome

      2016, Fish and Fish Oil in Health and Disease Prevention
    View all citing articles on Scopus

    The YOUNG study is part of the SEAFOODplus Integrated Project, which is funded by the European Commission through the 6th Framework Programme Contract FOOD-CT-2004-506359. The trial is registered at the U.S. National Library of Medicine (NCT00315770).

    View full text