Benefits
Fasting glucose and HbA1c support over three months
In two double-blind placebo-controlled trials in adults with newly diagnosed type 2 diabetes, ivy gourd preparations (1 g/day extract or a 500 mg/day herbal formulation) for about three months lowered fasting glucose and HbA1c more than placebo. Both trials were small and single-center, and the results apply only to that population.
Smaller blood sugar rise after a glucose drink
In a single-meal study, 122 healthy adults ate 20 g of raw ivy gourd leaves or a look-alike leaf before a 75 g glucose drink. Blood sugar one and two hours later was lower in the ivy gourd group, by about 20 and 11 mg/dL on average. Fasting levels did not differ. This is a one-time marker test, not a long-term result.
Glucose tolerance with a six-week leaf preparation
In an early double-blind trial in 32 adults with uncontrolled adult-onset diabetes, 10 of 16 people given a leaf preparation for six weeks showed a marked improvement in their glucose tolerance test, compared with none of 16 given a dummy preparation. The abstract reports only this count, not the size of the glucose change.
Triglyceride changes alongside glucose markers
In the three-month trial of a 500 mg/day herbal formulation in adults with newly diagnosed type 2 diabetes, triglycerides and VLDL cholesterol fell more than with placebo, while other lipid measures did not differ. A separate 90-day trial of a 1 g/day extract found no significant change in blood lipids.
Absorbable calcium from the leaves as a vegetable
In a crossover study in 19 healthy women, about 48% of the calcium in a meal of ivy gourd leaves was absorbed, compared with about 55% from milk. Fiber, oxalate and phytate in the leaves lowered absorption somewhat, but the leaves still delivered a useful share of their calcium as a food.
Carbohydrate enzyme inhibition in lab tests
Flavonoid glycosides isolated from ivy gourd leaves, including rutin and kaempferol glycosides, inhibited alpha-glucosidase, an enzyme that breaks down carbohydrates, in test-tube assays. This is laboratory work only; enzyme inhibition was not measured in people.
Mechanism of action
Alpha-glucosidase inhibition by leaf flavonoids
In lab assays, seven flavonoid glycosides isolated from the leaves slowed alpha-glucosidase, the gut enzyme that splits carbohydrates into absorbable sugars. Slower carbohydrate breakdown would be expected to blunt the rise in blood sugar after a meal. This is a proposed explanation from test-tube work, not a measured effect in people.
Lower liver glucose-6-phosphatase activity
In rats, an ethanol leaf extract lowered blood glucose and reduced the starvation-induced rise in glucose-6-phosphatase, the liver enzyme that releases glucose into the blood. A small human study in diabetic patients reported that raised plasma glucose-6-phosphatase activity moved back toward normal after six weeks of an extract given at a very high body-weight dose.
Liver glycogen storage from fruit pectin
In normal rats, pectin isolated from ivy gourd fruit lowered blood glucose, raised liver glycogen and increased glycogen synthase activity while lowering phosphorylase activity, which suggests more glucose was stored in the liver. These are animal findings at a high dose and have not been tested in people.
Clinical trials
Randomized, double-blind, placebo-controlled trial of a newly developed herbal formulation of Coccinia grandis (the group's preclinical work used an aqueous leaf extract), 500 mg once daily for three months versus placebo, at a teaching hospital in Galle, Sri Lanka. Funded by the National Research Council Sri Lanka (grant 17-029). (Wasana et al. 2021, Phytomedicine)
158 adults with newly diagnosed type 2 diabetes (mean age about 45), 79 per group; 145 completed.
Compared with placebo, HbA1c fell more (mean change 0.65 vs 0.08 percentage points, p<0.001), as did fasting plasma glucose, insulin, fructosamine, HOMA-IR, triglycerides and VLDL cholesterol (all p<0.001). Other measured outcomes did not differ from placebo. The abstract does not name a single primary outcome. Kidney, liver and blood counts and blood pressure stayed within normal ranges.
Double-blind, placebo-controlled randomized trial of 1 g/day of an alcoholic extract of Coccinia cordifolia (plant part not stated in the abstract) for 90 days, with standard diet and activity advice for all. Registered as NCT00502008; lead sponsor St. John's Research Institute with Gencor Pacific Group listed as an industry collaborator. The registered primary outcome was fasting and postprandial glucose and HbA1c at 90 days. (Kuriyan et al. 2008, Diabetes Care)
60 adults aged 35 to 60 with newly detected type 2 diabetes needing only lifestyle treatment (fasting glucose 110 to 180 mg/dL), not on glucose-lowering drugs.
Fasting glucose, postprandial glucose and HbA1c fell significantly more in the extract group than with placebo; at day 90 fasting and postprandial glucose in the extract group were 16% and 18% lower. Serum lipids did not change significantly.
Double-blind trial randomized by coin toss at two hospitals in Matara, Sri Lanka. After an overnight fast, participants ate 20 g of raw Coccinia grandis leaves with coconut and salt, or the same meal made with Erythrina indica leaves as placebo, then drank 75 g of glucose. Authors declared no conflicts. (Munasinghe et al. 2011, Exp Diabetes Res)
122 healthy adults aged 18 to 55, 61 per group; groups differed in sex balance.
Blood sugar was lower in the ivy gourd group at one hour (mean difference 20.2 mg/dL, 95% CI 4.81 to 35.5) and two hours (11.46 mg/dL, 95% CI 1.03 to 21.9). Fasting blood sugar did not differ (p=0.31). No hypoglycemia symptoms such as sweating or tremor were reported. This is a single-meal marker test.
Double-blind controlled trial of a preparation made from Coccinia indica leaves versus a dummy preparation for six weeks. (Azad Khan et al. 1979, Bangladesh Med Res Counc Bull)
32 adults with uncontrolled maturity-onset diabetes, 16 per group.
10 of 16 people in the leaf group showed a marked improvement in glucose tolerance versus none of 16 in the dummy group (p<0.001). The abstract does not report the dose or the size of the glucose change.
Small clinical study of a dried Coccinia indica extract given at 500 mg per kg body weight daily for six weeks, measuring plasma enzymes before and after treatment. No placebo group is described in the abstract. (Kamble et al. 1998, Indian J Med Sci)
30 people with diabetes of varying severity.
In severe diabetes, raised glucose-6-phosphatase and lactate dehydrogenase and reduced lipoprotein lipase activity moved back toward normal after treatment; mild diabetes showed no enzyme changes. The body-weight dose is far above the amounts used in later trials.
Three-way randomized crossover study comparing calcium absorption from ivy gourd leaves, winged bean pods and milk (about 100 mg calcium each, labeled with 44Ca) eaten with rice. (Charoenkiatkul et al. 2008, J Food Sci)
19 healthy women aged 20 to 45 in Thailand.
Fractional calcium absorption was 0.476 from ivy gourd, 0.391 from winged bean and 0.552 from milk; both vegetables were significantly lower than milk, partly due to phytate, oxalate and fiber.