Most nutrition experts agree that we need to “eat more veggies” as part of a healthy diet. Consuming more leafy greens (spinach, kale, collards, etc) may, in fact, be one of the most important components for overall health and weight loss. In addition to containing a host of fibers, vitamins, minerals and other micronutrients, leafy greens also have structures called thylakoids, which have been shown to manage cravings and increase satiety. So, the next time you add a side-salad to your lunch, you may also be helping yourself avoid the munchies later on.
Thylakoids are the photosynthetic membranes of chloroplasts that are found in the leaves of green plants. They are appearing on the health and research scene as a promising functional ingredient that exhibits a lipase-inhibiting effect leading to a reduced appetite. Thylakoids include both proteins and lipids (mainly omega-3s), 50% of each. They also contain chlorophyll, antioxidants, carotenoids, and vitamin E.
Studies using spinach extract containing thylakoids demonstrated an inhibitory effect on lipase activity, leading to delayed fat digestion. Why does delayed fat digestion matter? Research suggests that fat can activate dopaminergic systems to help avoid overeating. When the fat remains in the gastrointestinal lumen longer, signaling mechanisms are activated. These signals include the production of hormones such as cholecystokinin (CCK), glucagon-like-peptide-1 (GLP-1), and leptin, which are gastrointestinal satiety hormones that regulate appetite. 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 extracts reduce insulin levels and the hunger hormone, ghrelin. However, not only did participants consuming the spinach extract lose more body weight compared to a placebo, they also reported increased fullness, reduced hunger, and reduced desire for something salty or savory.
In addition, a three-month study of overweight and obese women found that consuming a dietary supplementation containing 5g of green-plant membranes per day increased weight loss, reduced total and LDL-cholesterol, and reduced the urge for sweets and chocolate. The positive impact on cravings cannot be understated since obesity is associated with dysregulation of hunger/satiety signals often blamed for overeating. Opposite effects on hormone signaling are associated with consumption of highly palatable processed foods, which are broken down too quickly making them easy to over consume.
While thylakoids work to delay digestion, they do not prevent fat from being digested (steatorrhea) to the extent of common drugs known as lipase-inhibitors. They also increase fatty acid oxidation in intestinal cells. While steatorrhea in a mouse occurs at levels over 35mg per day, the thylakoid-fed animals had 23 mg per day while the control group had 10 mg per day. The inhibitors contributed to weight loss because undigested fat was excreted in feces rather than being absorbed; however high excretion of fecal fat may also lead to adverse gastrointestinal events.
A 2016 rat study found that thylakoids not only reduced weight gain and body fat accumulation, but reduced visceral fat mass. Carrying “deep” fat around the organs is dangerous and has been linked to numerous health conditions associated with obesity including metabolic syndrome, type 2 diabetes, and cardiovascular disease.
Dietary thaylakoids also upregulated the expression of genes associated with intestinal fatty acid transport, fatty acid oxidation, and ketogenesis.
Since dysregulation of the intestinal barrier has been implicated in conditions such as diabetes, the modulation of the microbiotia may help explain the lowered insulin response associated with thylakoid consumption. The composition of microbiota may also be influenced by thylakoids in a prebiotic way of action. This rat study found lactobacilli were significantly increased in the thylakoid group compared to the control group. This is in line with other current studies reporting the anti-obesity effect of lactobacillus. Researchers believe this could be due to a direct influence on the growth of bacteria in the intestines or may be the result of a reduced appetite and food intake that indirectly affects the composition of the microbiota. Whether via direct or indirect manners, thylakoids have been found to affect food intake, regulate hunger hormones, and modulate the microbiota. Given the positive effects on satiety and the microbial composition without adverse GI effects, thylakoids are a logical choice to consider in the support of healthy weight management programs.
Important to note is that researchers have found that thylakoids may be heat-sensitive; industrial production of high-quality functional food ingredients should be via mild drying techniques.
Adding thylakoids to your daily routine, however, is simple. Include kale, spinach, broccoli, and other leafy greens to salads, soups, or even to your breakfast smoothie.