Food Bioscience: Bioactives for Obesity Research Programme
The overall aim of this programme is the discovery and validation of food bioactives which have a positive effect on body weight by:
- Modifying gut signals (stimulating satiety signal production, stimulating insulin release),
- Stimulating serotonin production/activity
- Eliciting an adipokine response.
Obesity has reached epidemic proportions 8-24% of European men and 10-35% of European women are obese. Weight regulation is governed by a complex interplay between biological, psychological and social factors. Peptides synthesised and released from the gastrointestinal tract are key players in influencing eating behaviour. Identifying bioactives that alter the gastric hormonal milieu, with associated changes in several of the signals known to affect appetite, may aid in the reduction of food intake and body weight over time. In this respect gut satiety signals such as GLP1, CCK, PYY, APOA4 and oxyntomodulin offer attractive bioactive targets/biomarkers in the search for milk bioactives which could alter food intake.
Connections between the hypothalamus and the gut play a major role in satiety and regulation of food intake. There is considerable evidence that increased serotonin activity in the brain is associated with appetite suppression. There are several potential sites where food might influence satiety through the 5HT system from increasing blood levels of tryptophan, the essential amino acid in 5HT synthesis, to enhancing its blood brain barrier transit. Likewise bioactives capable of inhibiting key regulatory enzymes such as tryptophan hydroxylase, 5-hydroxy-tryptophan decarboxylase or monoamine oxidase could be used in the modulation of satiety.
The composition of the gut microbiota affects energy harvest from the diet and energy storage in the host. Recent studies have shown that the gut microbiota suppresses fasting induced adipocyte factor (FiaF) which results in the induction of hepatic lipogenesis and the deposition of triglycerides in adipocytes. Bioactives that increase FiaF production may have a benefical effect on reduction of fat mass.
Dietary fatty acids have been shown to exert a variety of beneficial health effects such as reducing adiposity and increasing insulin sensitivity in rodents. Different fatty acids have different rates of oxidation and can contribute to differences in body weight gain, differences in size of fat depots and adipose tissue heterogeneity. In adipocytes, fatty acids and their derivatives can directly down regulate expression of adipogenic genes and various transcription factors (PPARs, SREBPs). For preadipocytes, exposure to different fatty acids affects their proliferation, differentiation and ultimately fat cell number at maturity.