BITTER leaf has been used as food and medicine for centuries in Africa. It has been used in the management and treatment of a number of health conditions, including malaria, diabetes, loss of appetite, diarrhoea, fatigue and cough.
Now, in a new study, researchers warn that high consumption of bitter leaf by humans might lead to anaemia, especially in menstruating and pregnant women.
Bitter leaf is consumed at least once a day by most people in the southeastern part of Nigeria as their traditional soup. Traditional soups made from it are used for curing headache by the Igbo and Yoruba.
They said that although bitter leaves have the ability to boost the immune system, excessive and continuous consumption of it might increase the risk of anaemia.
The researchers had assessed if an extract of bitter leaf could cause the breakdown of red blood cell in 10 adult Wistar rats. They were randomly divided into two groups of five rats each.
Animals in the first group had a saltwater solution and those in the second group had bitter leaf extract. At the end of 28 days of treatment, animals were fasted overnight and blood was collected for testing. The red blood cells (RBC) and white blood cells (WBC) counts were determined.
There was a significant decrease in packed cell volume (PCV), haemoglobin (Hb), red blood cell (RBC) and other blood parameters in rats treated with bitter leaf extract compared with those that only had saltwater solution.
The study, in the 2019 edition of the International Journal of Bio-Science and Bio-Technology, involved Dr Augustine I. Airaodion at the Federal University of Technology, Owerri, Imo State, in collaboration with John A. Ekenjoku, Emmanuel O. Ogbuagu, Uloaku Ogbuagu and Edith O. Airaodion.
The researchers said this might be an indication that bitter leaf either increases the breakdown of red blood cells or might have inhibited its production at this period of administration.
According to them, the decrease in the blood levels observed in this study might be suggestive that bitter leaf has possible potential to inhibit the release of erythropoietin, the hormone necessary to stimulate the normal bone marrow to produce red blood cells, from the kidneys.
They said that bitter leaf could also have affected the oxygen-carrying capacity of the blood and the amount of oxygen delivered to different organs of the body since red blood cells and haemoglobin (Hb) due to its low content of iron and proteins.
They, therefore, reasoned: “It is therefore possible that high consumption of bitter leaf by humans might lead to anaemia, especially in menstruating and pregnant women,” they declared.
Although how this happens is still unclear, they said bitter leaf contains a variety of chemical compounds, including saponins that previous studies had suggested could cause the destruction of red blood cells if ingested.
Previously, researchers had said that the risk of anaemia from consuming water extract of bitter leaf also varies from one individual to another, depending on their blood group.
The 2001 study, which involved Dr G. Oboh at the Federal University of Technology, Akure, said that bitter leaf contains saponin, a substance that makes red blood cell to break down.
This substance had a high effect on blood group O and genotype SS. Blood group A had the least susceptibility among the blood groups tested.
The various blood group, tested did not show a particular trend in their haemolystic activity, but genotype AA had the highest resistant to red blood cell breakdown while genotype SS had the least resistant among the genotypes tested.
Furthermore, the ethanol extract had a higher ability to break down red blood cell than the water extract on the various human red blood cells analysed, an indication that the ethanol extract may have a higher concentration of the saponin.
Given that bitter leaf is popularly consumed in Nigeria, either for its medicinal potential or food values, they said the fact remains that bitter leaf contains saponins which can be either beneficial or deleterious.
They added: “Part of the nutritional significance of saponins stems largely from their ability to reduce blood cholesterol. However, saponins have strong red blood cell breaking properties, when ingested orally, although they usually remain in the gastrointestinal tract but can sometimes leak into the blood during intestinal mucosa erosion, or damage.
“Following such a leakage, a number of pathological abnormalities have been identified among which may include liver damage, haemolysis, respiratory failure, convulsion and coma.”