Written by Joyce Smith, BS. Compared to the control group, participants who consumed 5 grams of spinach extract for three months had significantly reduced body weight and total and LDL-cholesterols, and experienced increased fullness, reduced hunger, and a reduced urge for sweets and chocolate.
Thylakoids, the chlorophyll-containing membranes found in leaves of green plants, contain lipids, vitamins A, E K, and the antioxidants lutein, zeaxanthin, carotenoids and chlorophyll.
Obesity is associated with dysregulation of hunger and satiety (a feeling of fullness) signals, and enhanced food cravings 1. Gut hormones, such as ghrelin, stimulate the desire for food 2 while glucagon-like-peptide-1 (GLP-1) suppresses the desire to eat more 3. Obese individuals who diet and lose weight often have an increased hunger and liking for palatable food, partly due to reduced secretion of the satiety hormones, leptin and GLP-1 4.
Previous studies have shown that, in response to a high fat diet, ingestion of spinach extract containing thylakoids increases satiety and releases the gut satiety hormone cholecystokinin. Cholecystokinin (CCK) stimulates the release of bile into the intestine and the secretion of pancreatic enzymes that delay fat digestion and fatty acid absorption in the body 4,5. When fat remains in the gastrointestinal lumen longer, the appetite-regulating satiety hormones CCK, GLP-1 and leptin, are triggered 4,5. GLP-1 decreases blood sugar levels in a glucose-dependent manner by enhancing the secretion of insulin 6. CCK also has positive effects on the brain’s reward system via serotonin release. This feel-good hormone acts as a reward molecule that also supports satiety. In addition, these thylakoid extracts reduce insulin levels 7 and the hunger hormone, ghrelin 8.
In a 3-month long, placebo-controlled, blinded study,9 thirty-eight overweight women (25-33 kg/m2) were randomized to consume a daily morning green drink containing 5 grams of spinach extract or a placebo. They were instructed to consume a well-balanced diet (3 meals/day and no diet changes) and to exercise 30 minutes each day. Two single-meal tests were done on day 1 and day 90 to elucidate the effects of long-term supplementation with thylakoids on appetite, body weight and metabolic parameters related to obesity, and in particular, to measure the release of the satiety-producing hormone GLP-1.
Compared to the control group, weight loss in the spinach group increased significantly over time (p<0.01). Total cholesterol (p<0.01) and LDL-cholesterol (p<0.05) also changed over time and were significantly reduced at 12 weeks. HDL- cholesterol and triglycerides were not affected over time or by treatment. GLP-1 increased significantly over the 3-month period (P<0.01). Participants consuming the spinach extract not only lost more body weight, they also reported increased fullness, reduced hunger, and a reduced urge for sweets and chocolate 10. Grehlin secretion was not affected.
Researchers concluded that the significant weight loss and reduction in cholesterol along with a decreased urge for palatable food may be due to the increased meal-related GLP-1 release that was sustained during the 90-day thylakoid intervention. These results suggest that green-plant thylakoids may be a potential supplement for appetite and body weight control.
Source: Montelius, Caroline, Daniel Erlandsson, Egzona Vitija, Eva-Lena Stenblom, Emil Egecioglu, and Charlotte Erlanson-Albertsson. “Body weight loss, reduced urge for palatable food and increased release of GLP-1 through daily supplementation with green-plant membranes for three months in overweight women.” Appetite 81 (2014): 295-304.
© 2017 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/)
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Posted April 1, 2019.
Joyce Smith, BS, is a degreed laboratory technologist. She received her bachelor of arts with a major in Chemistry and a minor in Biology from the University of Saskatchewan and her internship through the University of Saskatchewan College of Medicine and the Royal University Hospital in Saskatoon, Saskatchewan. She currently resides in Bloomingdale, IL.
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