But in what scientists have called a ‘huge scientific discovery’, a new Spanish study published in Clinical Nutrition journal has discovered that the regular consumption of sardines helps to prevent the onset of type 2 diabetes.
Researchers enrolled 152 patients aged 65 years and older who had been diagnosed with prediabetes (blood glucose levels between 100-124 mg/dl) from three different medical centres.
All the patients were put on a nutritional programme that sought to reduce the risk of them developing the disease, but only one group added 200 grams of sardines to their diet every week (two cans of sardines in olive oil). The participants received a list of recipes including canned sardines and were advised to eat the sardine whole, without removing the bones, as these are particularly rich in calcium and vitamin D.
Of those that did not include sardines in their diet, 27% were at a high risk of suffering from diabetes at the start of the study. After one year, 22% were in the same category. Among those who included sardines in their diet, 37% were at a high risk of suffering from diabetes at the start of the study. After one year, only 8% remained at a very high risk.
Improvements were also seen in other important biochemical parameters, such as a reduced insulin resistance index (HOMA-IR), increased "good" cholesterol (HDL), increased hormones that accelerate the breakdown of glucose (adiponectin) and decreased triglycerides and blood pressure, amongst others.
Diana D. Rizzolo, lead author, and lecturer and researcher of the Universitat Oberta de Catalunya's (UOC) Faculty of Health Sciences and the August Pi i Sunyer Biomedical Research Institute (IDIBAPS) said sardines should now be recommended by doctors, particularly to people over 65.
"Not only are sardines reasonably priced and easy to find, but they are safe and help to prevent the onset of type 2 diabetes,” she said. “It is easy to recommend this food during medical check-ups, and it is widely accepted by the population.”
"As we get older, restrictive diets (in terms of calories or food groups) can help to prevent the onset of diabetes. However, the cost-benefit ratio is not always positive, as we found in other studies," stated doctor Rizzolo. "However, the results lead us to believe that we could obtain an equally significant preventive effect in the younger population."
She stressed that sardines should be recommended as a food, pointing out that foods such as sardines - which are rich in taurine, omega 3, calcium and vitamin D - have a clear protective effect against the onset of diabetes does not mean that taking these supplements in isolation will have the same effect.
"Nutrients can play an essential role in the prevention and treatment of many different pathologies, but their effect is usually caused by the synergy that exists between them and the food that they are contained in,” she said. “Sardines will therefore have a protective element because they are rich in the aforementioned nutrients, whereas nutrients taken in isolation in the form of supplements won't work to the same extent."
The researchers have begun studying the effect of sardines on the intestinal microbiota in a second phase of the study, "since it affects the regulation of many biological process, and we need to understand if they have played a part in this protective effect against diabetes 2," said Rizzolo.
Type 2 diabetes preventive effects with a 12-months sardine-enriched diet in elderly population with prediabetes: An interventional, randomized and controlled trial (2021) D.A.Díaz-Rizzolo, A.Serra, C.Colungo, A.Sala-Vila, A.Sisó-Almirall, R.Gomis doi: https://doi.org/10.1016/j.clnu.2021.03.014
Prevention of Type 2 Diabetes through Sardines Consumption: An Integrative Review (2021) Diana A. Díaz-Rizzolo, Anna Miro & Ramon Gomis https://doi.org/10.1080/87559129.2020.1867565