Study under review: Acute effects of a spinach extract rich in thylakoids on satiety: A randomized controlled crossover trial
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 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 block the digestion of dietary fat. Unlike orlistat and other lipase inhibitors, however, thylakoids only delay the fat digestion, rather than blocking it.
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 and glucagon-like peptide-1 (GLP-1). GLP-1 was previously discussed in “Big breakfast or big dinner? Yet another meal-timing study” in Study Deep Dives Issue 8. In the intestines, 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, 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.
Other Articles in Issue #12 (October 2015)
Eat less, live more
Animal trials suggest that calorie restriction may extend lifespan. This is the longest human trial conducted thus far on the topic, and serves to inform calorie restriction’s health impacts and feasability.
Sugar Wars, Episode 2: “Fructose Strikes Back”
Few food components have been demonized as much as fructose in the past decade. With fructose being presumed guilty in metabolic syndrome and heart disease, this systematic review sheds light on it’s actual impact on blood lipids.
The case of the misleading yohimbe labels
What’s actually in a supplement bottle can be a mystery. These intrepid researchers investigated the actual contents of yohimbe bottles in order to see if this popular but possibly sometimes quasi-legal supplement is more (or less) than meets the eye.
- Interview: Robert Krikorian Ph.D.
Paying attention to omega-3s for ADHD
With more and more people being diagnosed with ADHD, there’s a continuing hunt for helpful treatments. Researchers tested an omega-3 supplement on young males, and also explored a potential dopamine-related mechanism.
- Interview: Trevor Kashey, Ph.D.
From jelly to muscle: collagen and body composition
Collagen has long been equated to junk protein, at least if you’re looking to gain muscle. Could it be underrated for this purpose? A trial of older men tested collagen protein to see if it could boost muscle gain and fat loss.
Throwdown, round 1: plant vs animal protein for metabolic syndrome
The DASH diet is frequently tested in clinical trials, and often performs well. But the diet’s formulation includes strong limitations on red meat, which may be based on outdated evidence. This study compared animal-protein rich diets with a typical DASH diet.
Can omega-3s modulate the mind-muscle connection?
While strength gains are usually associated with protein and muscle-related ergogenics, the nervous system isn’t targeted as often. This study explored a different type of omega-3 source (seal oil) for neuromuscular exercise effects.