To The Editor:
We read with great interest the recent major update of a previously published omega-3 meta-analysis by Bernasconi and colleagues of 40 studies with 135,267 participants, showing and impressive reduction in major cardiovascular outcomes.
1
O’Keefe et al suggested that marine omega-3 products are a reasonable option for people who do not routinely consume at least 1.5 fish or seafood meals per week.2
O’Keefe et al also suggested that the pesco-Mediterranean diet, with its emphasis on the consumption of fish and seafood, could be an ideal diet for cardioprotection.3
We analyzed the relationship between natural consumption of marine omega-3 (mainly shrimp) and the prevalence of cardiovascular disease.Using the National Health and Nutrition Examination Survey (NHANES), we identified all patients with heart failure, coronary artery disease (CAD), stroke, hypertension, and diabetes mellitus between 1999 and 2016. Mean ± standard deviation or median with interquartile range were reported for continuous variables and frequency with percentages were reported for categorical variables.
Of the 4177 subjects we analyzed through the NHANES database, 86% of patients reported consumption of shrimp. Persons who consumed shrimp were younger and had less hypertension and hyperlipidemia than those who did not consume shrimp (Table). Compared with non-shrimp-consuming persons, heart failure, CAD, and stroke were less prevalent in shrimp consumers (Table).
TableBaseline Characteristics of Patients With vs Without Shrimp Consumption
| Variables | Shrimp Consumption | P value | |
|---|---|---|---|
| Yes (n=3624) | No (n=553) | ||
| Demographics | |||
| Age (years) | 31.4±22.2 | 34.7±23.9 | ≤.05 |
| Females | 51.6 | 50.1 | .51 |
| Body mass index | 25.8±7.5 | 25.9±7.3 | .76 |
| White | 36.7 | 55.9 | ≤.05 |
| African American | 26.7 | 23.7 | .14 |
| Hispanic | 28.2 | 11.9 | ≤.05 |
| Other races | 5.1 | 5.4 | .77 |
| Comorbidities and risk factors | |||
| Cigarette smoking | 10.0 | 13.2 | ≤.05 |
| Heart failure | 1.52 | 2.7 | ≤.05 |
| Coronary artery disease | 1.85 | 2.7 | .17 |
| Stroke | 1.85 | 2.35 | .41 |
| Hypertension | 14.57 | 17.35 | .08 |
| Diabetes mellitus | 5.43 | 4.7 | .47 |
| Hyperlipidemia | 16.19 | 22.42 | ≤.05 |
| Total cholesterol level (mg/dL) | 187.3±42.1 | 185.7±9.9 | .40 |
| Direct HDL-cholesterol (mg/dL) | 55.0±15.6 | 54.6±17.3 | .58 |
| Triglyceride (mg/dL) | 130.9±110.2 | 129.8±82.1 | .82 |
| LDL-cholesterol (mg/dL) | 107.6±34.9 | 107.6±34.5 | .99 |
HDL, high-density lipoprotein; LDL, low-density lipoprotein.
Bang et al identified high consumption of shrimp in Greenland Eskimos as possibly contributing to their exceedingly low cardiac mortality.
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Subsequently, Silva et al indicated that, despite the high cholesterol content, consumption of shrimp was associated with an overall favorable impact on lipid levels.5
They noted a 7.1% rise in low-density lipoprotein (LDL), which was mitigated by a 12.1% rise in levels of high-density lipoprotein (HDL), leading to a net positive effect on total cholesterol to HDL ratios. This discrepancy has been attributed to the high omega-3 content and extremely low saturated fat levels in shrimp.5
Most importantly, Yuan et al observed, in a Chinese subpopulation, an almost 60% relative risk reduction in death from myocardial infarction in high consumers of seafood.6
Interestingly, this benefit occurred despite having no significant change in HDL or LDL levels, which had previously been regarded as the major mechanism of cardioprotection. This is consistent with the results demonstrated in the Reduction of Cardiovascular Events With Icosapent Ethyl-Intervention Trial (REDUCE-IT), in which the degree of reduction of cardiovascular risk was disproportionate to the extent of lipid reduction.
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The benefit of shrimp consumption has been hypothesized to be caused by the lipid independent cardioprotection effects regulated by omega-3 via its anti-inflammatory properties, its antioxidant effect, or by its ability to enhance parasympathetic tone.7
, 8
, 9
Our study has certain limitations. Several potential confounding variables exist, including the cooking techniques used, the extent and type of seafood co-consumption, and the exact amount of shrimp consumed. Also, this is an observational study, and thus the direct cause-and-effect relationships between consumption of shrimp and cardiovascular health cannot be ascertained through this study type.
In conclusion, consumption of shrimp is associated with an overall favorable effect on lipid profiles and decreased prevalence of cardiovascular risks compared with the effects on those who do not consume shrimp.
References
- Effect of omega-3 dosage on cardiovascular outcomes: an updated meta-analysis and meta-regression of interventional trials.(Mayo Clin Proc. [Epub ahead of print])
- Sea change for marine omega-3s: randomized trials show fish oil reduces cardiovascular events.Mayo Clin Proc. 2019; 94: 2524-2533
- A pesco-Mediterranean diet with intermittent fasting.J Am Coll Cardiol. 2020; 76: 1484-1493
- The composition of the Eskimo food in north western Greenland.Am J Clin Nutr. 1980; 33: 2657-2661
- Effects of shrimp consumption on plasma lipoproteins.Am J Clin Nutr. 1996; 64: 712-717
- Fish and shellfish consumption in relation to death from myocardial infarction among men in Shanghai, China.Am J Epidemiol. 2001; 154: 809-816
- Accumulated evidence on fish consumption and coronary heart disease mortality: a meta-analysis of cohort studies.Circulation. 2004; 109: 2705-2711
- The role of fish oil in arrhythmia prevention.J Cardiopulm Rehabil Prev. 2008; 28: 92-98
- Eicosapentaenoic acid-induced endothelium-dependent and -independent relaxation of sheep pulmonary artery.Eur J Pharmacol. 2010; 636: 108-113
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Grant Support: The authors report no grant support.
Potential Competing Interests: The authors report no competing interests
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- In Reply–Impact of a High-Shrimp Diet on Cardiovascular Risk: An NHANES AnalysisMayo Clinic ProceedingsVol. 96Issue 2
- PreviewWe greatly appreciate the interest by Narasimhan and colleagues in the recent major meta-analysis by Bernasconi et al.1 In this article, we analyzed 40 studies, including more than 135,000 participants, and demonstrated that omega-3 therapy was associated with major reductions in fatal myocardial infarction (MI); (–35%), total MI (–13%), coronary heart disease (CHD) events (–10%), and CHD mortality (–9%). We further demonstrated a strong dosage effect in which higher doses of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were associated with fewer cardiovascular disease (CVD) outcomes.
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