Eggplant has blood pressure-suppressing effect
Evidence suggests that a high-fibre and non-starchy vegetable such as eggplant supports the prevention of type-2 diabetes. Now, experts say eggplant can potentially serve as an important antihypertensive food.
In a new study, researchers say that eggplant powder lowers acute and chronic blood pressure levels in hypertensive rats by oral administration.
The main compound in the eggplant powder responsible for the antihypertensive effect was concluded to be Acetylcholine (ACh), a well-known animal neurotransmitter found in other foods such as milk, bamboo shoots and Shiitake mushrooms.
Eggplant (Solanum melongena), a popular vegetable that is consumed globally on a daily basis, is rich in dietary fibre and minerals, low in calories and protein, and contains vitamins such as B6, C, and folate.
Different eggplant species are grown around the world, ranging from dark purple to black, with some green and white varieties. Some eggplant varieties have rounder fruits whereas others have elongated fruits.
Besides its agricultural and nutritional importance, eggplant has a number of medicinal benefits. In several studies, extracts from eggplant fruits were shown to have excellent therapeutic effects on warts, burns, and many inflammatory diseases, such as stomatitis, arthritis, ulcer and gastritis.
Researchers say that its chemical constituents such as nasunin, a purple pigment in eggplant, contained in the peel, have antioxidant activity. Also, it contains chlorogenic acid (CA) reported to have blood sugar-lowering, cholesterol-lowering and liver protective effects.
Research has shown that when rabbits with high cholesterol consumed eggplant juice, it led to significantly lower weight and blood cholesterol levels.
Ethanolic extracts of eggplant fruits have been tested and shown to be effective against germs that cause diseases such as cholera and food poisoning from E.coli.
The fibre content of eggplant promotes healthy digestion, which helps the body get rid of waste materials and harmful toxins, thereby reducing the risk of colon and stomach cancer.
Eggplant’s high fibre and low soluble carbohydrate levels make it a good choice for helping to manage type 2 diabetes. African eggplant (Solanum kumba) was found to reduce blood glucose levels in diabetic rats.
These results suggest that a diet rich in eggplant may be a good way to reduce blood cholesterol, hypertension and oxidative stress in those with type 2 diabetes.
To test the blood pressure-lowering effect of the eggplant, the researchers repeatedly administer a water suspension of eggplant powder to hypertensive rats with almost same systolic blood pressure and body weights while pure water was administered to the control group.
The 2019 study was published in the journal, Food Chemistry.
Administration in each group continued for 28 days. Daily food and water consumption, body weights, and 24-hour urine volumes were recorded during the experimental period.
Before seven, 14, 21, and 28 days after the start of administration of eggplant extract, systolic blood pressure and diastolic blood pressure were measured using the method.
The systolic blood pressure in the eggplant group significantly decreased at three and nine hours by 4.81 and 10.0/ mm Hg, respectively, after giving the water suspension of eggplant powder compared with the control group.
The diastolic blood pressure also decreased, although the differences were not significant. The blood pressure of both groups returned to the initial values after 24 hours.
The systolic blood pressure of the eggplant group was significantly lower than that of the control group on days 14, 21, and 28 (by 10.1, 12.3, and 16.1/ mm Hg, respectively). The diastolic blood pressure also decreased (by 10.4/ mm Hg) on day 28.
These studies showed that the blood pressure-lowering effect of these compounds is dose-dependent and may have occurred by suppressing sympathetic nervous activity.
But, the researchers stated, “This study suggested that eggplant powders could provide antihypertensive effects at a small amount in hypertensive rats. In the future, the effect of daily ingestion of eggplant powder on blood pressure and the effective dosage should be investigated in a clinical trial.
“We hope that this report will be beneficial by publicizing the health effects of eggplant and promoting further studies and applications of eggplant as an antihypertensive food.”