Effects of L-Phenylalanine on Energy Intake and Glycaemia—Impacts on Appetite Perceptions, Gastrointestinal Hormones and Gastric Emptying in Healthy Males
In humans, phenylalanine stimulates plasma cholecystokinin (CCK) and pyloric pressures, both of which are important in the regulation of energy intake and gastric emptying. Gastric emptying is a key determinant of postprandial blood glucose. We evaluated the effects of intragastric phenylalanine on...
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MDPI AG
2020-06-01
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| Series: | Nutrients |
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| Online Access: | https://www.mdpi.com/2072-6643/12/6/1788 |
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| author | Penelope C. E. Fitzgerald Benoit Manoliu Benjamin Herbillon Robert E. Steinert Michael Horowitz Christine Feinle-Bisset |
| author_facet | Penelope C. E. Fitzgerald Benoit Manoliu Benjamin Herbillon Robert E. Steinert Michael Horowitz Christine Feinle-Bisset |
| author_sort | Penelope C. E. Fitzgerald |
| collection | DOAJ |
| description | In humans, phenylalanine stimulates plasma cholecystokinin (CCK) and pyloric pressures, both of which are important in the regulation of energy intake and gastric emptying. Gastric emptying is a key determinant of postprandial blood glucose. We evaluated the effects of intragastric phenylalanine on appetite perceptions and subsequent energy intake, and the glycaemic response to, and gastric emptying of, a mixed-nutrient drink. The study consisted of two parts, each including 16 healthy, lean males (age: 23 ± 1 years). In each part, participants received on three separate occasions, in randomised, double-blind fashion, 5 g (Phe-5 g) or 10g (‘Phe-10 g) L-phenylalanine, or control, intragastrically, 30 min before a standardised buffet-meal (part A), or a standardised mixed-nutrient drink (part B). In part A, plasma CCK and peptide-YY (PYY), and appetite perceptions, were measured at baseline, after phenylalanine alone, and following the buffet-meal, from which energy intake was assessed. In part B, plasma glucose, glucagon-like peptide-1 (GLP-1), insulin and glucagon were measured at baseline, after phenylalanine alone, and for 2 h following the drink. Gastric emptying of the drink was also measured by <sup>13</sup>C-acetate breath-test. Phe-10 g, but not Phe-5 g, stimulated plasma CCK (<i>p</i> = 0.01) and suppressed energy intake (<i>p</i> = 0.012); energy intake was correlated with stimulation of CCK (r = −0.4, <i>p</i> = 0.027), and tended to be associated with stimulation of PYY (r = −0.31, <i>p</i> = 0.082). Both Phe-10 g and Phe-5 g stimulated insulin and glucagon (all <i>p</i> < 0.05), but not GLP-1. Phe-10 g, but not Phe-5 g, reduced overall plasma glucose (<i>p</i> = 0.043) and peak plasma glucose (<i>p</i> = 0.017) in response to the mixed-nutrient drink. Phenylalanine had no effect on gastric emptying of the drink. In conclusion, our observations indicate that the energy intake-suppressant effect of phenylalanine is related to the stimulation of CCK and PYY, while the glucoregulatory effect may be independent of stimulation of plasma GLP-1 or slowing of gastric emptying. |
| first_indexed | 2024-03-10T19:08:18Z |
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| institution | Directory Open Access Journal |
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| language | English |
| last_indexed | 2024-03-10T19:08:18Z |
| publishDate | 2020-06-01 |
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| spelling | doaj.art-9b9ceb664fd3458b815b4072c96bf1652023-11-20T04:00:10ZengMDPI AGNutrients2072-66432020-06-01126178810.3390/nu12061788Effects of L-Phenylalanine on Energy Intake and Glycaemia—Impacts on Appetite Perceptions, Gastrointestinal Hormones and Gastric Emptying in Healthy MalesPenelope C. E. Fitzgerald0Benoit Manoliu1Benjamin Herbillon2Robert E. Steinert3Michael Horowitz4Christine Feinle-Bisset5Adelaide Medical School and Centre of Research Excellence in Translating Nutritional Science to Good Health, Level 5 Adelaide Health and Medical Sciences Building, Corner North Terrace and George Street, Adelaide 5005, AustraliaAdelaide Medical School and Centre of Research Excellence in Translating Nutritional Science to Good Health, Level 5 Adelaide Health and Medical Sciences Building, Corner North Terrace and George Street, Adelaide 5005, AustraliaAdelaide Medical School and Centre of Research Excellence in Translating Nutritional Science to Good Health, Level 5 Adelaide Health and Medical Sciences Building, Corner North Terrace and George Street, Adelaide 5005, AustraliaDepartment of Surgery, Division of Visceral and Transplantation Surgery, University Hospital Zürich, 8091 Zürich, SwitzerlandAdelaide Medical School and Centre of Research Excellence in Translating Nutritional Science to Good Health, Level 5 Adelaide Health and Medical Sciences Building, Corner North Terrace and George Street, Adelaide 5005, AustraliaAdelaide Medical School and Centre of Research Excellence in Translating Nutritional Science to Good Health, Level 5 Adelaide Health and Medical Sciences Building, Corner North Terrace and George Street, Adelaide 5005, AustraliaIn humans, phenylalanine stimulates plasma cholecystokinin (CCK) and pyloric pressures, both of which are important in the regulation of energy intake and gastric emptying. Gastric emptying is a key determinant of postprandial blood glucose. We evaluated the effects of intragastric phenylalanine on appetite perceptions and subsequent energy intake, and the glycaemic response to, and gastric emptying of, a mixed-nutrient drink. The study consisted of two parts, each including 16 healthy, lean males (age: 23 ± 1 years). In each part, participants received on three separate occasions, in randomised, double-blind fashion, 5 g (Phe-5 g) or 10g (‘Phe-10 g) L-phenylalanine, or control, intragastrically, 30 min before a standardised buffet-meal (part A), or a standardised mixed-nutrient drink (part B). In part A, plasma CCK and peptide-YY (PYY), and appetite perceptions, were measured at baseline, after phenylalanine alone, and following the buffet-meal, from which energy intake was assessed. In part B, plasma glucose, glucagon-like peptide-1 (GLP-1), insulin and glucagon were measured at baseline, after phenylalanine alone, and for 2 h following the drink. Gastric emptying of the drink was also measured by <sup>13</sup>C-acetate breath-test. Phe-10 g, but not Phe-5 g, stimulated plasma CCK (<i>p</i> = 0.01) and suppressed energy intake (<i>p</i> = 0.012); energy intake was correlated with stimulation of CCK (r = −0.4, <i>p</i> = 0.027), and tended to be associated with stimulation of PYY (r = −0.31, <i>p</i> = 0.082). Both Phe-10 g and Phe-5 g stimulated insulin and glucagon (all <i>p</i> < 0.05), but not GLP-1. Phe-10 g, but not Phe-5 g, reduced overall plasma glucose (<i>p</i> = 0.043) and peak plasma glucose (<i>p</i> = 0.017) in response to the mixed-nutrient drink. Phenylalanine had no effect on gastric emptying of the drink. In conclusion, our observations indicate that the energy intake-suppressant effect of phenylalanine is related to the stimulation of CCK and PYY, while the glucoregulatory effect may be independent of stimulation of plasma GLP-1 or slowing of gastric emptying.https://www.mdpi.com/2072-6643/12/6/1788food intakeappetite regulationblood glucose controlpostprandialamino acidcholecystokinin |
| spellingShingle | Penelope C. E. Fitzgerald Benoit Manoliu Benjamin Herbillon Robert E. Steinert Michael Horowitz Christine Feinle-Bisset Effects of L-Phenylalanine on Energy Intake and Glycaemia—Impacts on Appetite Perceptions, Gastrointestinal Hormones and Gastric Emptying in Healthy Males Nutrients food intake appetite regulation blood glucose control postprandial amino acid cholecystokinin |
| title | Effects of L-Phenylalanine on Energy Intake and Glycaemia—Impacts on Appetite Perceptions, Gastrointestinal Hormones and Gastric Emptying in Healthy Males |
| title_full | Effects of L-Phenylalanine on Energy Intake and Glycaemia—Impacts on Appetite Perceptions, Gastrointestinal Hormones and Gastric Emptying in Healthy Males |
| title_fullStr | Effects of L-Phenylalanine on Energy Intake and Glycaemia—Impacts on Appetite Perceptions, Gastrointestinal Hormones and Gastric Emptying in Healthy Males |
| title_full_unstemmed | Effects of L-Phenylalanine on Energy Intake and Glycaemia—Impacts on Appetite Perceptions, Gastrointestinal Hormones and Gastric Emptying in Healthy Males |
| title_short | Effects of L-Phenylalanine on Energy Intake and Glycaemia—Impacts on Appetite Perceptions, Gastrointestinal Hormones and Gastric Emptying in Healthy Males |
| title_sort | effects of l phenylalanine on energy intake and glycaemia impacts on appetite perceptions gastrointestinal hormones and gastric emptying in healthy males |
| topic | food intake appetite regulation blood glucose control postprandial amino acid cholecystokinin |
| url | https://www.mdpi.com/2072-6643/12/6/1788 |
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