Effects of Exercise and Galactooligosaccharide Supplementation on Inflammation and Iron Absorption (FexerGOS) (FexerGOS)

Effects of Exercise and Galactooligosaccharide Supplementation on Inflammation and Iron Absorption (FexerGOS)

Effects of Exercise and Acute and Chronic Galactooligosaccharide Supplementation on Inflammation and Iron Absorption in Female Athletes

Iron depletion is common in female athletes depending on the sports discipline. Endurance and resistance exercise can induce inflammation thereby reducing dietary iron absorption. Galacto-oligosaccharides (GOS) improved iron absorption in young healthy women and infants, and improved gut inflammation in iron-supplemented infants. A stable isotope study will be performed to investigate the effect exercise and acute and chronic GOS supplementation on inflammation and iron absorption in female athletes.

Iron depletion is common in athletes, particularly in females, reaching prevalence rates up to 70% depending on the sports discipline. As iron is essential for energy production and oxygen transport, a deficiency can impair performance, especially in endurance athletes. Iron deficiency in athletes may be caused by inadequate intake, but reduced iron absorption and increased losses also seem to play a role. Both endurance and resistance exercise at a high intensity, can induce inflammation resulting in a hepcidin response via interleukin-6 (IL-6) regulation. Hepcidin is the master regulator of systemic iron homeostasis, and a recent study in adult males showed that vigorous exercise decreases dietary iron absorption associated with increases in IL-6 and hepcidin. Iron losses induced by exercise have been attributed to several factors, including gastrointestinal bleeding associated with endothelial damage, haematuria, haemolysis, and increased sweating. Galacto-oligosaccharides (GOS) have been shown to acutely enhance iron absorption in young, healthy women. In Kenyan infants with a high infectious disease burden, chronic GOS administration improved iron absorption and mitigated the negative effects of iron supplementation on gut inflammation, likely mediated by its bifidogenic effect. Whether GOS has the potential of improving iron absorption has not been studied in athletes. The study aims are to determine 1) the effects of a bout of resistance exercise at 70% 1 repetition maximum (RM) on inflammation, hepcidin and iron absorption in high performance female team athletes; and 2) the effect of acute and chronic GOS supplementation on iron absorption in response to the exercise bout. The trial will entail two series of three iron absorption conditions separated by six weeks of GOS supplementation (10 g/day). The study participants will be 22 female university athletes recruited from the hockey, soccer and netball teams of North-West University, Potchefstroom, South Africa. At baseline, the first series of three iron absorption studies will be conducted, all measuring iron absorption from a supplement administered with labelled ferrous fumarate in the following conditions: 1) after a period of rest; 2) three hours after an acute resistance exercise bout; and 3) three hours after an acute resistance exercise bout, co-administered with GOS. Following this, participants will consume GOS daily for six weeks, followed by an identical series of iron absorption studies. Markers of systemic and gut inflammation, hepcidin, microflora composition and iron status indicators before and after the GOS intervention will be determined. In addition, erythrocyte iron incorporation will be determined after both series of isotope studies. Furthermore, the kinetics of isotope appearance, inflammatory markers, and hepcidin for 24 hours during each of the six iron absorption studies will be investigated. The primary hypotheses are that fractional iron absorption from a supplemental dose of ferrous fumarate will be: 1) lower three hours post exercise than post resting period; 2) higher with co-administration of GOS than without, both before and after six-week GOS intervention; and 3) higher after six-week intervention with GOS compared to baseline. The secondary hypotheses are: 1) acute exercise bout will result in increased inflammatory and hepcidin response before and after intervention with GOS but the intervention may mediate these two responses; 2) chronic GOS intervention will increase relative abundance of Bifidobacterium spp, reduce gut inflammation and improve gut integrity and gut health; 3) chronic GOS intervention will improve iron status.

Participants will receive 10 g of GOS daily for 6 weeks. Fractional iron absorption will be determined pre- and post the 6-week intervention from 3 conditions: 1) after a period of rest; 2) three hours after an acute resistance exercise bout without GOS and 3) three hours after an acute resistance exercise bout, co-administered with 10 g GOS.

10 g of GOS provided as 14 g of powder will be consumed after mixing it in water or yoghurt. The absorption study test drinks administered during the 3 test conditions will be comprised as follows: Post rest period - 50 mg of iron as ferrous fumarate (Fefum) supplement, 6 mg 54Fe as Fefum and 300 ml of water with sucrose and lactose. Post exercise bout - 50 mg of iron as Fefum, 6 mg 58Fe as Fefum and 300 ml of water with sucrose and lactose. Post exercise bout co-administered with GOS - 50 mg of iron as Fefum, 6 mg 57Fe as Fefum and 300 ml of water with 10 g GOS.

Fractional iron absorption will be measured after an exercise bout with and without co-administration of GOS.

Fractional iron absorption will be measured at rest and after an exercise bout before and after a 6-week intervention with GOS.

Interleukin 6 (IL-6) will be measured over 24 hours after exercise as a marker of exercise-induced inflammation.

Alpha-1-acid glycoprotein (AGP) will be measured in plasma to determine the presence of chronic inflammation.

Hepcidin, a major regulator of iron absorption and influenced by exercise-induced inflammation, will be measured in plasma over 24 hours.

The following lipid mediators will be measured over 24 hours in plasma in response to exercise-induced inflammation:17-hydroxydocosahexaenoicacid (17-HDHA); 5-, 8-, 9-, 11-, 12-, 15 and 18- hydroxyeicosapentaenoicacid (HEPE); 5-, 8-, 11-, 12- and 15-hydroxyeicosatetraenoicacid (HETE); prostaglandin (PG) E2 and D2, and resolvin (Rv) D1 and E1).

Plasma erythropoietin, a marker of erythropoiesis, will be measured before and after period of rest and exercise.

Kinetics of serum iron isotope appearance during a period of rest and post-exercise, before and after intervention with GOS, and with and without co-administration of GOS.

Concentration of short chain fatty acids - acetate, propionate, isobutyrate, butyrate, formate, isovalerate will be measured in faecal samples before and after the 6-week intervention with GOS.

Faecal zonulin will be measured at baseline and endpoint as a marker of the integrity of the intestinal mucosal barrier.

Intestinal fatty acid-binding protein (I-FABP), a marker of intestinal damage, will be measured in plasma at baseline and endpoint.

Haemoglobin will be measured in whole blood to determine presence of anaemia and for calculation of fractional iron absorption.

Soluble transferrin receptor (sTfR) will be measured in plasma to determine the presence of iron deficiency.

Fibroblast growth factor 21 (FGF-21) will be measured in plasma as a marker of environmental enteric dysfunction (EED).

Insulin-like growth factor 1 (IGF-1) will be measured in plasma as on of the markers of environmental enteric dysfunction.

Two methods: Quansys EED ELISA and the VitMin lab s-ELISA will be used and compared in the measurement of: RBP4 (µmol/L), and Thyroglobulin (µg/L).

Two methods: Quansys EED ELISA and the VitMin lab s-ELISA will be used and compared in the measurement of Ferritin (µg/L).

Two methods: Quansys EED ELISA and the VitMin lab s-ELISA will be used and compared in the measurement of sTfR (mg/L).

Two methods: Quansys EED ELISA and the VitMin lab s-ELISA will be used and compared in the measurement of CRP (mg/L).

Two methods: Quansys EED ELISA and the VitMin lab s-ELISA will be used and compared in the measurement of AGP (g/L).

Two methods: Quansys EED ELISA and the VitMin lab s-ELISA will be used and compared in the measurement of I-FABP (pg/mL).

Two methods: Quansys EED ELISA and the VitMin lab s-ELISA will be used and compared in the measurement of Thyroglobulin (µg/L).

Inclusion Criteria: High performance female team sport athlete. Train at least 3 days or 6 hours per week in a team sport. Having low to moderate iron stores. Estimated maximal oxygen uptake (VO2 max) of ≥40 ml/kg/min. Willingness to consume the study supplement GOS during the intervention period. Willingness not to consume nutritional supplements containing iron, vitamin C and/or pre- or probiotics (excluding food and beverages containing live cultures such as yoghurt, raw milk and cheese) two weeks prior to, as well as during the study. Exclusion Criteria: Haemoglobin <11 g/dl. Treated or self-reported chronic disease, malabsorptive or gastrointestinal disorders (e.g. irritable bowel syndrome, functional bloating). Treatment with oral antibiotics in the four weeks prior to screening visit. Pregnancy or lactation. Subjects who cannot be expected to comply with the study protocol. Difficulty drawing blood due to poor quality veins. Individuals that have a fear of needles or suffer from vaso-vagal episodes when exposed to blood. Participants who plan to start or stop the use of contraceptives before or during study period. Participants who are lactose intolerant. Participants who donated blood in the past 4 months or plan to donate during the study period. Participants who use chronic anti-inflammatory medication such as corticosteroids or non-steroidal anti-inflammatory medication (NSAIDS). Current consumption of iron, or pre- or probiotic supplements other than the supplements provided (Participants will be asked to discontinue use two weeks prior to screening).