Intake of palmitic acid and its association with metabolic flexibility in middle-aged individuals: a preliminary study

Objective: This study aimed to assess the relationship between dietary palmitic acid (PA) intake and its association with body fat deposition and metabolic flexibility (MF) in middle-aged healthy individuals. Methods: Fifteen healthy participants (n = 15; 6 males, 9 females) with a mean age of 54 were enlisted. They were subjected to graded exercise tests using a cycle ergometer coupled with a calorimeter. Respiratory gas exchange was evaluated to determine two MF parameters. First, the MF index was derived by multiplying peak fatty acid oxidation (PFO) per kg of fat-free mass (FFM) with the percentage of VO2max at PFO. The second parameter, peak energy substrates’ oxidation (aka PESO), was computed by aggregating the kilocalories from PFO and peak carbohydrate oxidation, normalized per kg FFM. Dietary intake was gauged using a 7-day dietary record. Spearman’s regression was employed to analyze the association between dietary intake of specific fat classes, PA, MF parameters, and body fat percentage. Results: Preliminary results demonstrate that dietary saturated fatty acids (SFA) within physiological limits correlate with enhanced substrate oxidation capacity. This suggests augmented MF in middle-aged subjects. Among dietary SFA, PA was identified as the primary factor in this favorable correlation. Conclusions: Our initial observations, even though preliminary, strongly suggest a beneficial association between PA intake, MF, and body fat percentage. This underscores the potential nutritional importance of PA in promoting MF. Significance Statement Disparities in data regarding the health effects of dietary fats may arise from the distinct roles various dietary fatty acids play in MF.