Dangerous belly fat
Obesity-related metabolic disorders such as dyslipidaemia and insulin resistance are risk factors for cardiovascular disease, especially in older people. Visceral adipose tissue, better known as abdominal fat, has a decisive influence on this. These are fat cells that lie under the muscle layer in the abdomen and surround the internal organs. Visceral adipose tissue actually serves as an energy reserve in the absence of food, but it also has numerous negative properties. For example, it can increase the release of inflammatory and other messenger substances and favour vascular-damaging blood lipids. People with too much belly fat often suffer from high blood pressure and have an increased risk of cardiovascular disease, fatty liver and type 2 diabetes. Although weight loss is considered an effective means of reducing abdominal fat, long-term success is often limited. In older people, who are at increased risk of cardiovascular disease per se, weight loss can even be detrimental in terms of muscle tone. Therefore, the guidelines for older adults recommend moderate calorie restriction and maintenance of muscle mass.
A comparison of two diets
Against this background, scientists from DIfE and Charité - Universitätsmedizin Berlin have investigated the effects of a specific dietary pattern on visceral adipose tissue and the cardiometabolic risk profile within the "NutriAct" competence cluster of nutrition research. For the three-year NutriAct nutrition study, 502 men and women aged between 50 and 80 were randomly assigned to an intervention group or a control group. The intervention group followed the NutriAct dietary pattern with a high proportion of monounsaturated and polyunsaturated fatty acids, predominantly plant-based proteins and fibre. They were given specially prepared foods and took part in eleven small group sessions including nutrition, cooking and lifestyle counselling over a 12-month period. The control group, on the other hand, followed the standard recommendations of the German Society of Nutrition (DGE) and received three nutritional counselling sessions and some free conventional foods for a year.
MRI examination shows clear results
To analyse visceral fat tissue, a magnetic resonance imaging (MRI) scan was carried out on a subgroup of 300 test subjects at the beginning and after 12 months of dietary intervention. This measurement method is much more precise than the commonly used measurement of waist circumference and is considered the gold standard. The MRI examination showed a significant reduction in visceral fat tissue in the intervention group, while there were no changes in the control group. "This reduction was largely mediated by the increased intake of polyunsaturated fatty acids and was accompanied by an improvement in the cardiometabolic risk marker LDL cholesterol. The altered intake of monounsaturated fatty acids, proteins and dietary fibre does not appear to have been the main driver of the effect on visceral adipose tissue," said Prof. Knut Mai, DZHK scientist and head of the Department of Human Nutrition at DIfE. Interestingly, this effect was independent of the slight weight loss seen in both groups, which emphasises the importance of the specific nutrient composition. These findings contribute to a deeper understanding of the role of specific nutrients and dietary patterns in reducing visceral adipose tissue and improving the cardiometabolic profile.
Optimising nutritional recommendations for 50 plus
"The results are particularly relevant for older people who have an increased risk of cardiometabolic diseases," explains Nina Meyer, first author of the study. "The specific diet could serve as a preventive measure against such diseases without the need for drastic weight reduction and loss of muscle mass." The findings of the study could be used to improve dietary recommendations for people aged 50 and over and to adapt individual nutritional advice. "Compared to other diets, the NutriAct dietary pattern can be more easily integrated into everyday life and help to reduce the risk of cardiovascular disease in the general population," says Meyer. In future studies, the researchers want to further clarify the underlying mechanisms of these effects and analyse the influence of the dietary pattern on other cardiovascular systems, such as heart function, in more detail.
Original publication: Improvement in Visceral Adipose Tissue and LDL Cholesterol by High PUFA Intake: 1-Year Results of theNutriAct Trial (Meyer et al., 2024)
Source: press release DIfE (in German only)
