Nav: Home

Fatty fish without environmental pollutants protect against type 2 diabetes

June 19, 2019

If the fatty fish we eat were free of environmental pollutants, it would reduce our risk of developing type 2 diabetes. However, the pollutants in the fish have the opposite effect and appears to eliminate the protective effect from fatty fish intake. This has been shown by researchers at Chalmers University of Technology in Sweden, using innovative methods that could be used to address several questions about food and health in future studies.

Research on the effect of fish consumption on diabetes risk has produced contradictory results in recent years. Some studies show that eating a lot of fish reduces the risk of developing type 2 diabetes, while others show it has no effect, and some studies show it even tends to increase the risk. Researchers at Chalmers University of Technology conducted a study with an entirely new design and have now arrived at a possible explanation for this puzzle.

"We managed to separate the effect of the fish per se on diabetes risk from the effect of various environmental pollutants that are present in fish," says Lin Shi, a Postdoc in Food and Nutrition science. "Our study showed that fish consumption as a whole has no effect on diabetes risk. We then screened out the effect of environmental pollutants using a new data analysis method based on machine learning. We were then able to see that fish themselves provide clear protection against type 2 diabetes."

"Protection is provided primarily by consumption of fatty fish. However, at the same time, we saw a link between high consumption of fatty fish and high contents of environmental pollutants in the blood."

Environmental pollutants measured in the present study are persistent organic pollutants (POPs), for example dioxins, DDT and PCB. Previous research has shown that they may be linked to increased risk of type 2 diabetes. The varying effect of fish on diabetes risk in different studies could therefore be due to varying levels of consumption of fish from polluted areas in the different studies.

According to the Swedish National Food Agency, food is the main source of exposure to dioxins and PCBs. These substances are fat soluble and are primarily found in fatty animal foods such as fish, meat and dairy products. Particularly high contents are found in fatty fish such as herring and wild salmon from polluted areas. In Sweden, for example, this means the Baltic Sea, the Gulf of Bothnia and the biggest lakes, Vänern and Vättern.

The Chalmers researchers also used a new method to find out what the study participants had eaten, as a complement to questionnaires on dietary habits. Previous research has often relied entirely on questionnaires. This produces sources of error that may also have contributed to the contradictory results concerning fish and type 2 diabetes.

"Using a technique known as mass spectrometry based metabolomics, we identified around 30 biomarkers in blood samples, i.e. specific molecules that could be used to objectively measure of how much fish the study participants had consumed," says Lin Shi.

Overall, the new methodology provides considerably better tools for this research field. They can be used to better discern which dietary factors are the actual causes of different types of health effects.

"Metabolomics and the new way of analysing data give us new opportunities to distinguish between effects from different exposures that are correlated," says Rikard Landberg, Professor of Food and Nutrition Science at Chalmers. "This is very important as otherwise it is difficult to determine whether it is diet, environmental pollutants or both that affect the risks of disease."

More about the study:

The study is a case-control study nested in a prospective cohort in Västerbotten in northern Sweden. The participants had completed questionnaires on dietary habits and lifestyle, and provided blood samples, which were frozen. A total of 421 people who had developed type 2 diabetes after an average of 7 years were included, and they were compared with 421 healthy control individuals. The original blood samples were then analysed. In addition, blood samples were analysed that had been provided ten years after the first blood samples by 149 of the case-control pairs.
-end-
The study is reported in the article "Joint analysis of metabolite markers of fish intake and persistent organic pollutants in relation to type 2 diabetes risk in Swedish adults", which was published in The Journal of Nutrition. In addition to the Chalmers researchers, researchers from Umeå University, Karolinska Institutet, the National Institute for Health and Welfare in Finland and the University of Eastern Finland also participated.

https://academic.oup.com/jn/article-lookup/doi/10.1093/jn/nxz068

Chalmers University of Technology

Related Diabetes Articles:

The role of vitamin A in diabetes
There has been no known link between diabetes and vitamin A -- until now.
Can continuous glucose monitoring improve diabetes control in patients with type 1 diabetes who inject insulin
Two studies in the Jan. 24/31 issue of JAMA find that use of a sensor implanted under the skin that continuously monitors glucose levels resulted in improved levels in patients with type 1 diabetes who inject insulin multiple times a day, compared to conventional treatment.
Complications of type 2 diabetes affect quality of life, care can lead to diabetes burnout
T2D Lifestyle, a national survey by Health Union of more than 400 individuals experiencing type 2 diabetes (T2D), reveals that patients not only struggle with commonly understood complications, but also numerous lesser known ones that people do not associate with diabetes.
Type 2 diabetes and obesity -- what do we really know?
Social and economic factors have led to a dramatic rise in type 2 diabetes and obesity around the world.
A better way to predict diabetes
An international team of researchers has discovered a simple, accurate new way to predict which women with gestational diabetes will develop type 2 diabetes after delivery.
The Lancet Diabetes & Endocrinology: Older Americans with diabetes living longer without disability, US study shows
Older Americans with diabetes born in the 1940s are living longer and with less disability performing day to day tasks than those born 10 years earlier, according to new research published in The Lancet Diabetes & Endocrinology journal.
Reverse your diabetes -- and you can stay diabetes-free long-term
A new study from Newcastle University, UK, has shown that people who reverse their diabetes and then keep their weight down remain free of diabetes.
New cause of diabetes
Although insulin-producing cells are found in the endocrine tissue of the pancreas, a new mouse study suggests that abnormalities in the exocrine tissue could cause cell non-autonomous effects that promotes diabetes-like symptoms.
The Lancet Diabetes & Endocrinology: Reducing sugar content in sugar-sweetened drinks by 40 percent over 5 years could prevent 1.5 million cases of overweight and obesity in the UK and 300,000 cases of diabetes
A new study published in The Lancet Diabetes & Endocrinology journal suggests that reducing sugar content in sugar sweetened drinks (including fruit juices) in the UK by 40 percent over five years, without replacing them with any artificial sweeteners, could prevent 500,000 cases of overweight and 1 million cases of obesity, in turn preventing around 300,000 cases of type 2 diabetes, over two decades.
Breastfeeding lowers risk of type 2 diabetes following gestational diabetes
Women with gestational diabetes who consistently and continuously breastfeed from the time of giving birth are half as likely to develop type 2 diabetes within two years after delivery, according to a study from Kaiser Permanente published today in Annals of Internal Medicine.

Related Diabetes Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Digital Manipulation
Technology has reshaped our lives in amazing ways. But at what cost? This hour, TED speakers reveal how what we see, read, believe — even how we vote — can be manipulated by the technology we use. Guests include journalist Carole Cadwalladr, consumer advocate Finn Myrstad, writer and marketing professor Scott Galloway, behavioral designer Nir Eyal, and computer graphics researcher Doug Roble.
Now Playing: Science for the People

#530 Why Aren't We Dead Yet?
We only notice our immune systems when they aren't working properly, or when they're under attack. How does our immune system understand what bits of us are us, and what bits are invading germs and viruses? How different are human immune systems from the immune systems of other creatures? And is the immune system so often the target of sketchy medical advice? Those questions and more, this week in our conversation with author Idan Ben-Barak about his book "Why Aren't We Dead Yet?: The Survivor’s Guide to the Immune System".