Adults' health-related values and preferences related to reducing or modifying dietary fat intake: a mixed methods...

To systematically summarise people's health-related values and preferences related to fat intake.

We searched five databases for studies reporting people's perspectives on fats. Screening, data extraction and risk of bias assessment were performed by two independent reviewers. Data was analysed using a convergent integrated approach and the certainty of evidence was assessed using the Grading of Recommendations, Assessment, Development and Evaluation methodology.

Qualitative and quantitative studies from any country or language.

Primary studies of adults, with or without cardiometabolic conditions.

From 52 166 records, we included eleven quantitative and two qualitative studies; studies were primarily conducted in high-income countries. Five main themes were identified: (i) negative perception of fat in food, (ii) positive perception of vegetable oil as being beneficial to health, (iii) willingness to lower fat consumption, (iv) willingness to pay for healthier fat content and (v) barriers towards unsaturated fat consumption. The most frequently reported themes were negative perception of fat and willingness to consume low-fat products, while prioritising vegetable oil as a healthy fat. The evidence certainty for these themes was very low to moderate, rated down for risk of bias and indirectness issues.

People's perception of fats and oils in diets is complex and often contradictory; most viewed high-fat products as unhealthy and associated with weight gain, while vegetable oils were generally perceived as beneficial. However, views varied significantly depending on sex, age and dietary patterns. Overall, the evidence supporting these perceptions is of moderate to very low certainty and to inform guideline recommendations more research is needed.