Am I less hungry after I eats me spinach?

Popeye ate his spinach in order to be strong. This study looked at spinach for a different purpose—to see if a proprietary extract could suppress hunger and decrease food consumption in overweight people. The product examined in this trial is an extract of thylakoids from spinach. Plants and algae have cell bodies called chloroplasts, which is where chlorophyll is contained and where the process of photosynthesis happens.

Within the chloroplasts of plants, and also in some bacteria, is a compartment called the thylakoid (pictured in Figure 1). Certain reactions in the photosynthesis pathway take place in the thylakoid to provide energy to the plant or bacterium. Previous research^[1] from this team of scientists showed that concentrated thylakoid preparations can inhibit the breakdown of fatty acids in the intestines, similar to the way that lipase inhibitors like orlistat^[2] block the digestion of dietary fat. Unlike orlistat and other lipase inhibitors, however, thylakoids only delay the fat digestion, rather than blocking it.

Figure 1: What are the thylakoids?

Delaying fat digestion has been previously shown by these researchers to increase the production of certain hormones that contribute to feelings of satiety, or fullness, and a reduced desire to consume more food. These hormones include cholecystokinin^[3] and glucagon-like peptide-1^[4] (GLP-1). GLP-1 was previously discussed in “Big breakfast or big dinner? Yet another meal-timing study” in NERD Issue 8. In the intestines^[5], GLP-1 production increases pancreatic insulin secretion in the presence of glucose, and also slows the emptying of the stomach, prolonging feelings of fullness. In the brain^[6], GLP-1 reduces the pleasure and sense of reward associated with eating food.

This study evaluated an extract of thylakoids, the compartment of the plant cell where some photosynthesis reactions take place. Concentrated thylakoids are hypothesized to affect hormones that control feelings of hunger and desire for food, by slowing down the digestion of fats.