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Oily Fish Lower Risk of Diabetes

Jul 6, 2021
 
Editor: David L. Joffe, BSPharm, CDE, FACA

Author: Shalonda Kimble, PharmD Candidate, South College School of Pharmacy 

People who reported two or more servings per week of oily fish consumption had a 22% lower risk of developing type 2 diabetes. 

Studies investigating the relationship between fish consumption and the risk of T2D have reported contradictory results. Geographical variations in the fish-T2D relationship have been indicated by meta-analyses of prospective cohort studies, with an inverse association when combining studies performed in China, Japan, and Australia; no association in European studies; and a positive association between studies carried out in the U.S. Variations in the fat content of fish eaten by diverse study populations may be one possible reason for such regional variations in the fish-T2D relationship. Consumption of fatty fish rather than lean fish was inversely correlated with T2D risk in a pooled study of eight European cohorts, but results from other cohort studies on the possible impact of fish’s fat content on T2D risk were minimal and inconsistent. Additional extensive cohort studies on fish consumption and risk of T2D that differentiate between fatty and non-fatty fish are still needed. In this study, in a large prospective study of a U.K. population, researchers investigated the associations between oily and nonoily fish consumption and T2D risk. Researchers also explored the association between the regular use of fish oil supplements and the risk of T2D. 

 

The U.K. Biobank is a broad, prospective, observational study designed to provide a database for genetic, environmental, and lifestyle factors associated with a wide range of diseases, including diabetes, to be investigated. Between 2006 and 2010, 500,000 men and women of different ethnicities aged 37-73 years were recruited from 22 centers across England, Wales, and Scotland. In a touchscreen food frequency questionnaire that included 29 questions about the average consumption of major foods or food groups throughout the previous year, data on usual dietary intake at baseline was gathered. Baseline diabetes was identified through several procedures that considered diabetes type and diagnosis sources such as self-report or medical records. Using hospital inpatient records from the Hospital Episode Statistics for England, Scottish Morbidity Report data for Scotland and the Wales Patient Episode Database, diabetes during follow-up was established. 

At the beginning of the study, 17.5% and 16.2% of contributors reported oily fish and nonoily fish consumption of 2 or more servings per week. There was a median of 10.1 years of follow-up, and 7,262 incident cases of T2D were identified. When related with participants who testified to never consuming oily fish, those reporting two or more servings per week of oily fish consumption had a 22% (95% CI 14–29%) lower risk of T2D. Each further increase in oily fish intake of 1 serving/week was associated with an 8% (4–11%) lower risk of T2D. For secondary outcomes, 31.4% of participants reported regular use of fish oil supplements. Compared with contributors without normal fish oil usage, those who reported taking regular fish oil supplements had a 9% (95% CI 4–14%) lower risk of T2D.  

In conclusion, the results suggest that oily fish consumption, but not nonoily fish, is correlated with a lower risk of T2D in a broad prospective analysis of the U.K. population. Despite the positive correlation between the overall consumption of fish and the risk of T2D found in a few previous studies performed in Western people, the results support preserving the existing dietary guideline regarding increased oily fish consumption. A lower risk of T2D was also associated with the use of fish oil supplements, and the lowest risk was found among individuals who were continually using fish oil over time. Therefore, as part of a balanced dietary pattern, it is currently wise to prescribe fresh oily fish instead of fish oil supplements for diabetes prevention. Further prospective studies performed in other populations with distinct sociodemographic and lifestyle histories are warranted to validate the results. When analyzing the results from the current research, there were many possible limitations, one of which that the participants were predominantly of European descent and healthier than the U.K. general population. 

 Practice Pearls: 

  • Consumption of oily fish, but not nonoily fish, is associated with a lower risk of T2D. 
  • Additional prospective studies performed in other populations with different sociodemographic and lifestyle backgrounds are necessary to confirm findings. 
  • It is prudent to recommend fresh oily fish as a part of a healthy dietary pattern instead of fish oil supplements for diabetes prevention. 

 

Chen, Guo-Chong, et al. “Association of Oily and Nonoily Fish Consumption and Fish Oil Supplements With Incident Type 2 Diabetes: A Large Population-Based Prospective Study.” Diabetes Care, American Diabetes Association, January 6, 2021  

Schwingshackl, Lukas et al. “Food groups and risk of type 2 diabetes mellitus: a systematic review and meta-analysis of prospective studies.” European journal of epidemiology vol. 32,5 (2017): 363-375.  

 

Shalonda Kimble, PharmD Candidate, South College School of Pharmacy