These diseases include diabetes, Alzheimer's, Parkinson's, hypertension, heart disease, and non-alcoholic fatty liver disease.
MO is a member of the Moringacea family, and is a major crop in Asia and Africa. Previous research has found that its bioactive components, such as vitamins, flavonoids, phenolic acids, tannins, saponins and isothiocyanates, have various health benefits.
These components are said to be effective against insulin resistance, hypercholesterolaemia, high blood pressure, cancer, and general inflammation.
Based on this, researchers at the University of Connecticut and Mexico's Universidad Autonoma de Sinaloa reviewed studies on MO's ability to prevent and alleviate the aforementioned chronic conditions.
Lowering cholesterol and blood pressure
They reported on MO's hypolipidaemic effects, saying its flavonoids and phenolic compounds were shown to aid in regulating lipids, delaying cholesterol absorption, and decreasing plasma cholesterol concentrations.
They added: "Saponins, found in MO leaves, prevented the absorption of cholesterol…causing a reduction in the enterohepatic circulation of bile acids and increasing their faecal excretion."
This was offset by "enhanced bile acid synthesis from cholesterol in the liver", resulting in lower plasma cholesterol.
The leaves' methanol extract, on the other hand, was found to ameliorate drug-induced liver and kidney damage. In guinea pigs, they prevented non-alcoholic fatty liver disease "in a model of hepatic steatosis, as measured by lower concentrations of hepatic cholesterol and triglycerides".
Apart from reducing cholesterol and protecting against non-alcoholic fatty liver disease, MO leaves also lowered blood pressure in rats.
The researchers said this was likely via a "calcium antagonist effect", which has been shown to help treat high blood pressure.
In addition, they referred to a recent study that had reported MO's reductive effect on vascular oxidation in spontaneously hypertensive rats.
MO's anti-diabetic effects were found in its isothiocyanates, which lowered insulin resistance, while its flavonoids and phenolic acids were said to increase insulin sensitivity.
MO also influenced carbohydrate metabolism by restoring β-cell function and integrity, "increasing insulin activity, (and) improving glucose uptake and utilisation".
Additionally, several studies have documented MO leaves' ability to protect cells from oxidative DNA damage linked to cancer and degenerative diseases.
One such study reported on MO leaves inhibiting "the viability of acute myeloid leukemia, acute lymphoblastic leukaemia and hepatocellular carcinoma cells", attributing this quality to several bioactive compounds.
MO leaf extract was also shown to contain the growth of breast and pancreatic cancer cells, as well as to increase the efficacy of chemotherapy.
MO was also said to be able to enhance memory, as well as prevent oxidative stress in Alzheimer's disease; it was found to alter brain monoamines and electrical patterns in rats.
Furthermore, in a mouse model of Parkinson's disease, a bioactive compound in MO was shown to stem from myrosinase hydrolysis, which favourably modulated inflammatory and apoptotic pathways, as well as oxidative stress.
The researchers wrote that MO leaves' benefits for sufferers of the abovementioned conditions have been 'well documented', especially in terms of animal studies.
However, they concluded: "Additional studies in humans, including clinical trials, are needed to confirm these effects of MO on chronic diseases."
"Bioactive Components in Moringa Oleifera Leaves Protect against Chronic Disease"
Authors: Marcela Vergara-Jimenez, et al.