When it comes to obesity, much of the focus is on restricting and reducing foods. But given the struggle to combat the global weight crisis, scientists are turning to what we should be consuming to prevent weight gain. One food group that is in the spotlight of research is fish and seafood.
Obesity is on the rise across the globe, affecting all ages and socio-economic groups. It is a well-known risk for chronic diseases such as type 2 diabetes and heart disease, as well as premature death.
Aside from genetics, weight management will always come back to energy consumed and energy used. A variety of factors contribute to an imbalance in these, but dietary pattern is the most significant in the majority of cases.
Within the diet, the quality of food can influence satiety, appetite and energy expenditure, as can specific nutrients. This means that food quality and nutrient-density are important factors to consider when looking at addressing obesity.
A review was designed to explore the observation studies and intervention trials looking at obesity, insulin resistance and/or type 2 diabetes and fish or seafood consumption.
Animal trials were also reviewed to explore the potential mechanisms that may explain the influence of seafood consumption on these conditions.
Many studies were reviewed as part of this study, but a few key areas were of particular interest.
One observation study indicated that fatty fish intake was associated with increased body weight. However, these findings were not supported by the data from intervention trials and animal studies. The researchers suggested that consumption of marine-based omega-3 fatty acids were likely of importance for reducing fat mass.
The majority of intervention and animal studies that explored insulin resistance and type 2 diabetes returned consistent data. They suggested that a frequent intake of lean seafood reduced fasting and post-prandial risk markers of insulin resistance compared to land-based meat consumption.
Lean seafood consumption also improved insulin sensitivity in insulin-resistant adults. The one exception to this finding was shellfish and fried lean fish, which were associated with impaired glycaemic control.
Fatty fish consumption in healthy studies had a neutral effect on the fasting markers of insulin sensitivity. It was also reported to improve post-prandial glycaemic control.
However, a high intake of fatty fish in people with diabetes or hypertension may impair their glycaemic control. This may need to be combined with exercise or weight reduction to minimise the impact.
Fatty fish intake increased the plasma concentration of adiponectin, a signalling molecule that improves insulin sensitivity. High intake of seafood may also reduce CRP compared to a high meat intake, although not all studies observed this relationship.
The researchers concluded that further studies are needed to confirm the effects of seafood consumption on energy intake, obesity and insulin resistance. There are conflicting findings in certain areas, especially when looking at healthy subjects compared to insulin resistant or type 2 diabetic patients.
It was suggested that future studies should explore the contribution of the trace elements, vitamins and undesirable compounds such as heavy metals that are present in seafood. They also argued that future research should look into responders and non-responders in controlled trials, to better understand the health effects of seafood.
Liaset, B., Øyen, J., Jacques, H., Kristiansen, K. and Madsen, L., 2019. Seafood intake and the development of obesity, insulin resistance and type 2 diabetes. Nutrition research reviews, pp.1-22.