Benefits
Body fat in a 12-week trial of a lotus leaf extract drink
In a randomized double-blind trial in China in adults with a BMI of 24 to 28, 12 weeks of a hot-water lotus leaf extract lowered whole-body fat versus control in men and women, and visceral fat and waist size in men. It was a single trial sponsored by a Meiji company with Meiji co-authors; the abstract gives no dose or effect sizes, and a registry entry filed years later lists 95 rather than 60 participants.
Blood cholesterol in a trial of a potato and lotus leaf blend
In 19 female university students in Korea, 8 weeks of a drink combining potato and lotus leaf extracts with hydroxycitric acid lowered total cholesterol compared with placebo. Body fat, BMI, triglycerides, LDL and HDL did not differ significantly between groups. Because it was a blend, the result cannot be credited to lotus leaf itself.
Fat storage in rodents fed high-fat diets
In mice on a high-fat diet, a lotus leaf extract given for 5 weeks limited gains in body weight, fat pad weight and liver triglycerides. In obese rats, a water extract given for 6 weeks cut visceral fat by about 46 to 58% depending on dose. These are animal results only and do not show the same effect in people.
Nuciferine and fat metabolism in lab and animal studies
Nuciferine, a main alkaloid of lotus leaf, was added to a high-fat diet at 0.1% for 12 weeks in mice and reduced body weight and fat mass while raising energy expenditure. In rats on a high-fat diet it limited weight gain and shifted gut bacteria. These findings come from animals only.
Mechanism of action
Slows starch and fat digestion in lab tests
In test-tube work, lotus leaf extract blocked alpha-amylase and lipase, the enzymes that break down starch and fat, in a dose-dependent way. In muscle cells it raised lipid metabolism and expression of UCP3, a protein linked to energy use.
Quercetin glucuronide and fat breakdown in cells
Quercetin 3-O-glucuronide and quercetin are the key components of hot-water lotus leaf extract. In cell studies they promoted the breakdown of stored triglycerides through the cAMP pathway. This has not been measured in people.
AMPK signaling in liver and fat tissue
In mice and liver cells, nuciferine switched on AMPK, an energy-sensing enzyme, which lowered fat-making enzymes (SREBP1, FAS, ACC) and raised fat-breakdown enzymes (HSL, ATGL). Blocking AMPK removed these effects in cells.
Alkaloids act on dopamine receptors in lab tests
Alkaloids isolated from lotus leaves blocked dopamine D1 and D2 receptors in cell assays, and in rats nuciferine and N-nornuciferine were well absorbed by mouth and, when injected, rapidly reached the brain. What this means for appetite, mood or safety in people is unknown.
Clinical trials
Randomized, double-blind trial of a hot-water extract of sun-dried lotus leaves (main component quercetin 3-glucuronide) for 12 weeks. Co-authors are from Meiji Co., Ltd., and the registry entry (NCT04651023) is sponsored by Shanghai Meiji Health Science and Technology. (Ye et al. 2022, Nat Prod Res)
Adults with overweight (BMI 24 to 28) in China; the abstract reports n = 60. The registry entry, filed in 2020 for a study run in 2009, lists 95 adults aged 40 to 60 with a BMI of 23 to 30 randomized to a placebo drink or 1 g/day or 2 g/day of extract.
Compared with non-intervention control groups, whole-body fat decreased significantly in men and women, and men also had significant reductions in visceral fat and waist circumference. The abstract gives no effect sizes, dose or blood lipid results, and calls the comparison groups non-intervention controls, while the registry describes a placebo drink.
Randomized, placebo-controlled study of a drink made mainly from potato and lotus leaf extracts combined with hydroxycitric acid, prepared by a Korean company's health food laboratory; the lotus leaf amount is not stated. (Lee et al. 2015, J Exerc Nutrition Biochem)
19 female university students in Korea (9 blend, 10 placebo).
Total cholesterol fell from about 185 to 168 mg/dL with the blend while staying near 189 to 194 mg/dL on placebo, a significant group by time interaction. BMI, percent body fat, abdominal fat, triglycerides, LDL and HDL showed no significant difference between groups. With three active parts and 19 people, the trial cannot show an effect of lotus leaf itself.