Does Co-administration of Lactate Affect Postprandial Nutrient Absorption and Fat Disposition?

A recent study showed that oral lactate administration slowed gastric emptying, increased the feeling of being full, induced satiety, and decreased the anticipated future food intake compared with intravenous administration. This shows that lactate has direct effects in the GI tract, which could improve substrate utilization after meals and thereby improve metabolic health. However, it remains unknown whether oral lactate administration has similar effects in other populations (i.e. individuals with obesity) and in relation to a meal.

To address these potential effects, the investigators aim to implement and validate a new tracer method in Denmark to measure meal fat partitioning using an orally ingested fluorine-labeled fatty acid analog (18F-fluoro-6-thiaheptadecanoic acid, 18F-FTHA) combined with positron emission tomography coupled to computed tomography (PET-CT). In a previous study using the aforementioned method, it has been shown that individuals with an impaired glucose tolerance have increased myocardial fatty acid uptake, not explained by potential confounding factors and that this is associated with a reduced systolic ejection fraction. In a recent study, it was found that subjects with insulin resistance have a higher uptake of free fatty acids in visceral adipose tissue compared with subjects without insulin resistance.

This method will enable the investigators to determine how the addition of lactate to a test meal will affect meal fat partitioning. Previous methods for determining fatty acid partitioning and accumulation have either been limited to only determining the accumulation in non-oxidative tissues or very invasive or difficult to perform, making this the first method to non-invasively simultaneously measure the partitioning of meal fatty acids in all human organs.

Work package 1 (WP1):

The investigators will also include 8 healthy individuals (HbA1c mmol/mol< 39, age 50+ years) as a healthy control group, who will be studied twice in a randomized trial following ingestion of a liquid test meal to determine the differences in meal fat partitioning between insulin-sensitive and insulin-resistant individuals and to determine the intraindividual variation in meal fat partitioning. Furthermore, the extra PET scans performed in the healthy individuals will be used for precise quantification of the radiation exposure with the PET method (dosimetry) and validation of the PET method.