Effects of daily bitter gourd consumption for 2 months among pre-diabetics;
an intervention trial in Moshi, Tanzania
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Beschreibung
Prevalence of pre-diabetes and type 2 diabetes mellitus are on the rise not only in high-income countries, but also in low- and middle-income countries such as the United Republic of Tanzania, whereas many diabetes cases remain undiagnosed. Type 2 diabetes is often linked to overweight and obesity due to excess caloric intakes and sedentary lifestyles. In Tanzania, the most recent estimated prevalence of pre-diabetes was 9.1% (in 2013) and of diabetes 3.5% (in 2015). Access to proper diabetes care and management is often insufficient in Tanzania. The increasing rates of diabetes will amplify the already existent burden on affected individuals and the country on its own. Alternative strategies such as the use of anti-diabetic plants, may be one possibility to fight against rising blood glucose levels and prevent the onset of type 2 diabetes mellitus. One medicinal plant with hypoglycemic effects is Momordica charantia, also known as bitter gourd or bitter melon. Bitter gourd has shown anti-diabetic effects in cell, animal, and human studies, but no clear recommendation on the application of bitter gourd variety, dosage, and mean of consumption is available. Bitter gourd is most commonly cultivated and consumed in Asian countries. Bitter gourd is also available in Sub-Saharan countries, mainly collected from the wild. The current research project was divided into two studies which were conducted in Moshi, Tanzania, between 2011-2014. The first study aimed to assess knowledge and usage of bitter gourd as well as knowledge and management of diabetes among diabetic patients. The second study aimed to assess anti-diabetic effects of 2.5 g dry raw bitter gourd powder consumption per day among pre-diabetics.
The first study was a cross-sectional survey with structured and open-ended questions and conducted at the Kilimanjaro Christian Medical Centre in Moshi, in 2011. Out of 155 patients interviewed, 7% had heard about bitter gourd before, whereas 5% used it as a medicinal plant in adjunct to oral anti-diabetic drugs (OAD). Although bitter gourd was not well known, bitter tasting plants were consumed by almost all participants and around 50% stated to apply medicinal plants for various conditions. Symptoms were perceived between months and years before diagnosis. In regard to diabetes knowledge, symptoms were most known among patients followed by complications and causes. Almost all were on medical treatment, either on OAD, or insulin, or a combinations of both. Complications such as impaired sight and impotence were stated by the patients. Around 90% stated to have changed their lifestyle after diagnosis toward higher intakes of vegetables and increased physical activity.
The second study was a cross-over designed, randomized, placebo-controlled, single-blind, dietary intervention trial among pre-diabetic participants in 2013/14. It was conducted at the Kilimanjaro Clinical Research Institute in Moshi and included two eight-week intervention periods, separated by a four week washout period. Fasting plasma glucose (FPG), HbA1c, blood pressure (BP), and blood lipids were main assessed outcomes. Participants were recruited with the help of a pre-screening and screening phase in 2013. The following main inclusion criteria were applied: FPG 5.6-7 mmol/L, HbA1c 5.7-7.5%, BMI 27-35 kg/m², BP 90/60-160/110 mmHg, age 30-65 years, no clinically diagnosed diseases, no pregnancy or breastfeeding among women.
A total of 1256 people were pre-screened, and 382 who fit age and BMI criteria were further screened. Around 35% of screened people had pre-diabetic FPG values. After assessing all inclusion criteria, 61 participants (54% female, 46% male) started the intervention study. After the study duration of six months, the dropout rate was 15% with 52 participants finishing the study. Statistical analysis with a general linear mixed model revealed a period, but no carry-over effect. The change of FPG levels significantly differed (p=0.01) between the bitter gourd and placebo groups, with a mean decrease in the bitter gourd (-0.2 mmol/L) and mean increase in the placebo group (0.1 mmol/L). Change of FPG was greater among participants with a higher baseline FPG. Other outcomes did not differ significantly. However, in the overall study group, there was a significant decrease of FPG and BP from the time of the screening (July-October 2013) until the start of the intervention study (October 2013).
In conclusion, the first study showed a positive attitude toward the use of medicinal plants. However, in case of bitter gourd, usage and knowledge were very low. As symptoms of diabetes were present a relatively long time before diagnosis, diabetes knowledge of diabetic patients was presumably gained after diagnosis with the help of health staff and information posters displayed in the clinic. In addition, diabetes care imposed extra burdens on some participants. The existence of complications shows the need to improve diabetes management, including possibilities to monitor long-term glucose levels.
The recruitment procedure of the second study revealed high rates of diagnosed and undiagnosed diabetes. The intervention study demonstrated a blood glucose lowering effect of daily bitter gourd consumption among pre-diabetics. The change of FPG prior to the study may be attributable to a behavior change after the screening. A combination of healthy lifestyle counseling and use of bitter gourd (with exception for pregnant or lactating women, and people with glucose-6-phosphatase-dehydrogenase deficiency) may be a feasible strategy to reduce blood glucose levels in that area.
Autor*in
Christine Ludwig