Oily fish and diabetes prevention

Omega-3, oily fish and diabetes prevention

Experts recommend people with diabetes consume a serve of oily fish 2-3 times a week. Here we explain why, and options for those who don’t like it.

The body is able to make many things it needs for good health, but we must get some from our diet. These are called essential nutrients. One of these essential nutrients is the ω-3 (omega-3 or n-3) polyunsaturated fatty acids: α-linolenic acid (ALA) from plants, which are found in high levels in oily fish, and some meat and some egg sources.

The body uses omega-3 fatty acids to make signalling molecules that regulate inflammation, immune function, clotting and cell growth.

There is substantial evidence that people who eat diets naturally high in omega-3 fatty acids have lower rates of heart disease and stroke. In the 1970s, for example, researchers found the Indigenous people of Greenland, known as the Inuit, had surprisingly low rates of heart disease, despite consuming a large proportion of fat in their diet.

A number of studies have tried to replicate these observations using fish oil. There is certainly beneficial effects on the level of cholesterol and fats in the blood stream, but whether fish oil supplements reduce the risk of heart disease, diabetes or other common diseases remains uncertain. 

Moreover, persistent organic pollutants such as dioxins and methyl mercury, found in fish, might cause problems of their own.

Oily fish alternatives

Nonetheless, experts recommended people with diabetes consume a meal of oily fish (such as salmon, herring, mackerel, anchovies, sardines and, to a lesser extent, tuna) 2-3 times every week to keep up their omega 3s.

Although enjoyable for some, many find this difficult to achieve or unpalatable. If this is the case, fortified foods with added amounts of ω-3 fat can prove useful, including bread, mayonnaise, yogurt, orange juice, pasta, milk, eggs, infant formula and even ice-cream.

Many people take supplements that contain the required amounts of ω-3, such as fish oils. However, the dose required to achieve any significant change in fat levels is quite high (> 2g/day). This can leave a ‘fishy’ aftertaste and it can be hard to sustain taking this large number of pills over a long period of time, especially if the effects on your health are modest at best.

References

• Ruzzin J, Jacobs DR.The secret story of fish: decreasing nutritional value due to pollution? Br J Nutr. 2012 Aug;108(3):397-9. doi: 10.1017/S0007114512002048. Epub 2012 May 24.
• Zhou Y, Tian C, Jia C. (2012) Association of fish and n-3 fatty acid intake with the risk of type 2 diabetes: a meta-analysis of prospective studies. Br J Nutr. Aug;108(3):408-17.
• Wu JH, Micha R, Imamura F, Pan A, Biggs ML, Ajaz O, Djousse L, Hu FB, Mozaffarian D. (2012) Omega-3 fatty acids and incident type 2 diabetes: a systematic review and meta-analysis. Br J Nutr. Jun;107 Suppl 2:S214-27.
• Mikami N, Hosokawa M, Miyashita K. (2012). Dietary combination of fish oil and taurine decreases fat accumulation and ameliorates blood glucose levels in type 2 diabetic/obese KK-A(y) mice. J Food Sci. 77(6):H114-20
• Müllner E, Brath H, Pleifer S, Schiermayr C, Baierl A, Wallner M, Fastian T, Millner Y, Paller K, Henriksen T, Poulsen HE, Forster E, Wagner KH. (2012). Vegetables and PUFA-rich plant oil reduce DNA strand breaks in individuals with type 2 diabetes. Mol Nutr Food Res. Nov 12. [Epub ahead of print]
• Zheng JS, Huang T, Yang J, Fu YQ, Li D. (2012). Marine N-3 polyunsaturated fatty acids are inversely associated with risk of type 2 diabetes in Asians: a systematic review and meta-analysis. PLoS One. 7(9):e44525. Epub.
• Oils and PUFA contents: http://integrativemed.kumc.edu/school-of-medicine/integrative-medicine/health-topics/healthy-cooking-oils.html
• Anoop Misra, Neha Singhal, and Lokesh Khurana. (2010). Obesity, the Metabolic Syndrome, and Type 2 Diabetes in Developing Countries: Role of Dietary Fats and Oils. J Am Coll Nutrvol. 29 no. 3 Supplement 1 289S-301S. Available here: http://www.jacn.org/content/29/3_Supplement_1/289S.long
• Nutrition evidence library: What is the effect of dietary PUFA intake on health and intermediate health outcomes? : http://www.nutritionevidencelibrary.com/evidence.cfm?evidence_summary_id=250137

Last reviewed 04/Jun/2020