Influence of a prudent diet on circulating cathepsin S in humans

BACKGROUND: Increased circulating cathepsin S levels have been linked to increased risk of cardiometabolic diseases and cancer. However, whether cathepsin S is a modifiable risk factor is unclear. We aimed to investigate the effects of a prudent diet on plasma cathepsin S levels in healthy individuals. FINDINGS: Explorative analyses of a randomized study were performed in 88 normal to slightly overweight and hyperlipidemic men and women (aged 25 to 65) that were randomly assigned to ad libitum prudent diet, i.e. healthy Nordic diet (ND) or a control group (habitual Western diet) for 6 weeks. Whereas all foods in the ND were provided, the control group was advised to consume their habitual diet throughout the study. The ND was in line with dietary recommendations, e.g. low in saturated fats, sugars and salt, but high in plant-based foods rich in fibre and unsaturated fats.The ND significantly decreased cathepsin S levels (from 20.1 (+/-4.0 SD) to 19.7 μg/L (+/-4.3 SD)) compared with control group (from 18.2 (+/-2.9 SD) to 19.1 μg/L (+/-3.8 SD)). This difference remained after adjusting for sex and change in insulin sensitivity (P = 0.03), and near significant after adjusting for baseline cathepsin S levels (P = 0.06), but not for change in weight or LDL-C. Changes in cathepsin S levels were directly correlated with change in LDL-C. CONCLUSIONS: Compared with a habitual control diet, a provided ad libitum healthy Nordic diet decreased cathepsin S levels in healthy individuals, possibly mediated by weight loss or lowered LDL-C. These differences between groups in cathepsin S were however not robust and therefore need further investigation.

Role of dietary fats in modulating cardiometabolic risk during moderate weight gain : a randomized double-blind overfeeding trial (LIPOGAIN study)

BACKGROUND: Whether the type of dietary fat could alter cardiometabolic responses to a hypercaloric diet is unknown. In addition, subclinical cardiometabolic consequences of moderate weight gain require further study. METHODS AND RESULTS: In a 7-week, double-blind, parallel-group, randomized controlled trial, 39 healthy, lean individuals (mean age of 27±4) consumed muffins (51% of energy [%E] from fat and 44%E refined carbohydrates) providing 750 kcal/day added to their habitual diets. All muffins had identical contents, except for type of fat; sunflower oil rich in polyunsaturated fatty acids (PUFA diet) or palm oil rich in saturated fatty acids (SFA diet). Despite comparable weight gain in the 2 groups, total: high-density lipoprotein (HDL) cholesterol, low-density lipoprotein:HDL cholesterol, and apolipoprotein B:AI ratios decreased during the PUFA versus the SFA diet (-0.37±0.59 versus +0.07±0.29, -0.31±0.49 versus +0.05±0.28, and -0.07±0.11 versus +0.01±0.07, P=0.003, P=0.007, and P=0.01 for between-group differences), whereas no significant differences were observed for other cardiometabolic risk markers. In the whole group (ie, independently of fat type), body weight increased (+2.2%, P<0.001) together with increased plasma proinsulin (+21%, P=0.007), insulin (+17%, P=0.003), proprotein convertase subtilisin/kexin type 9, (+9%, P=0.008) fibroblast growth factor-21 (+31%, P=0.04), endothelial markers vascular cell adhesion molecule-1, intercellular adhesion molecule-1, and E-selectin (+9, +5, and +10%, respectively, P<0.01 for all), whereas nonesterified fatty acids decreased (-28%, P=0.001). CONCLUSIONS: Excess energy from PUFA versus SFA reduces atherogenic lipoproteins. Modest weight gain in young individuals induces hyperproinsulinemia and increases biomarkers of endothelial dysfunction, effects that may be partly outweighed by the lipid-lowering effects of PUFA. CLINICAL TRIAL REGISTRATION URL: http://ClinicalTrials.gov. Unique identifier: NCT01427140.