Intraduodenal Administration of Intact Pea Protein Effectively Reduces Food Intake in Both Lean and Obese Male Subjects

BACKGROUND: Human duodenal mucosa secretes increased levels of satiety signals upon exposure to intact protein. However, after oral protein ingestion, gastric digestion leaves little intact proteins to enter the duodenum. This study investigated whether bypassing the stomach, through intraduodenal administration, affects hormone release and food-intake to a larger extent than orally administered protein in both lean and obese subjects. METHODS: Ten lean (BMI:23.0±0.7 kg/m²) and ten obese (BMI:33.4±1.4 kg/m²) healthy male subjects were included. All subjects randomly received either pea protein solutions (250 mg/kg bodyweight in 0.4 ml/kg bodyweight of water) or placebo (0.4 ml/kg bodyweight of water), either orally or intraduodenally via a naso-duodenal tube. Appetite-profile, plasma GLP-1, CCK, and PYY concentrations were determined over a 2 h period. After 2 h, subjects received an ad-libitum meal and food-intake was recorded. RESULTS: CCK levels were increased at 10(p<0.02) and 20(p<0.01) minutes after intraduodenal protein administration (IPA), in obese subjects, compared to lean subjects, but also compared to oral protein administration (OPA)(p<0.04). GLP-1 levels increased after IPA in obese subjects after 90(p<0.02) to 120(p<0.01) minutes, compared to OPA. Food-intake was reduced after IPA both in lean and obese subjects (-168.9±40 kcal (p<0.01) and -298.2±44 kcal (p<0.01), respectively), compared to placebo. Also, in obese subjects, food-intake was decreased after IPA (-132.6±42 kcal; p<0.01), compared to OPA. CONCLUSIONS: Prevention of gastric proteolysis through bypassing the stomach effectively reduces food intake, and seems to affect obese subjects to a greater extent than lean subjects. Enteric coating of intact protein supplements may provide an effective dietary strategy in the prevention/treatment of obesity

Changes in plasma CCK release (pM) after oral and intraduodenal treatments with pea protein and placebo.

<p>CCK release was increased during the first 10 minutes after oral pea protein ingestion in both lean (A) and obese (B) subjects. However, after intraduodenal pea protein administration, CCK levels remained elevated for 15 minutes, and the levels were higher when compared to oral protein administration. Values are expressed as mean ± SEM. * Significantly different from placebo treatment (p<0.05). # Significantly different from oral protein treatment (p<0.05).</p

<i>Ad libitum</i> food intake (g) after oral and intraduodenal treatments with pea protein and placebo.

<p>Oral protein ingestion did not affect food intake. Both lean and obese subjects decreased food intake after intraduodenal protein administration compared to the placebo treatment. Moreover, obese subjects decreased their food intake also when compared to oral protein treatment, whereas this was not the case for lean subjects. ID: Intraduodenal treatment; O: oral treatment. Values are expressed as mean ± SEM<b> </b>. * Significantly different from intraduodenal placebo treatment (p<0.05). # Significantly different from oral protein treatment (p<0.05).</p

Subject characteristics at baseline.

<p>All data are mean ± SEM.</p><p>• Difference between lean and obese subjects (p<0.05).</p><p># p-Value = 0.054 between lean and obese subject.</p

Changes in hunger, fullness, and satiety (mmVAS) after oral and intraduodenal treatments with pea protein and placebo.

<p>Feelings of hunger did not change in lean subjects after between treatments (A), whereas in obese subjects, hunger decreased at 30 minutes after the oral pea protein ingestion (B). Feelings of fullness were increased after intraduodenal pea protein treatment for both lean (C) and obese (D) subjects. Satiety did not change over time when compared to placebo treatments for both lean (E) and obese (F) subjects. Values are expressed as mean ± SEM. * Significantly different from placebo treatment (p<0.05). # Significantly different from oral protein treatment (p<0.05).</p

Changes in plasma PYY release (pM) after oral and intraduodenal treatments with pea protein and placebo.

<p>Oral pea protein ingestion did not affect PYY release in lean subjects (A), whereas intraduodenal pea protein administration significantly increased the release of PYY from 15 minutes after pea protein administration until the end of the test. In obese subjects (B), PYY release was significantly increased from 30 minutes until the end of the test for both protein treatments. Values are expressed as mean ± SEM. * Significantly different from placebo treatment (p<0.05). # Significantly different from oral protein treatment (p<0.05).</p