A recent study published in the journal Food & Function has explored the potential benefits of blackcurrant and citrus extracts in reducing blood sugar levels after meals, which could help prevent type 2 diabetes. The study was conducted by a team of European researchers from the UK, Italy, and Finland.
The researchers conducted two separate trials to test the effects of drinks containing blackcurrant and citrus extracts on postprandial glycemia, which is the rise in blood sugar levels after eating. They also measured other outcomes such as insulin secretion, gut hormone release, appetite, and cognitive function.
In the first trial, called the GLU-FX study, they compared the effects of four different drinks containing low or high doses of blackcurrant (BC) or sweet orange (SO) polyphenols, which are natural compounds with antioxidant and anti-inflammatory properties. Polyphenols are believed to slow down the absorption of glucose into the blood by inhibiting enzymes that break down carbohydrates.
The second trial, called the GLU-MIX study, compared the effects of two drinks containing either fiber-rich citrus pulp or a combination of citrus pulp and BC extract. Fiber is known to slow down the emptying of the stomach and increase the feeling of fullness, which could also help lower blood sugar levels.
The participants in both trials were healthy adults who were overweight or obese, as these are risk factors for developing type 2 diabetes. They consumed one of the test drinks before a standard breakfast and lunch, and their blood samples were collected at regular intervals for three hours after each meal. They also completed questionnaires to assess their appetite and cognitive function.
What the study found
The main finding of the study was that BC extract reduced blood sugar levels immediately after meals, but higher doses were not more effective than lower doses. The researchers also found no evidence that adding citrus polyphenols or fiber enhanced this effect.
The authors explained that BC extract may have a rapid but short-lived effect on blood sugar levels, which could be beneficial for preventing spikes that can damage the cells that produce insulin. However, they cautioned that these findings are not conclusive and need to be confirmed by larger and longer-term studies.
The study also found some evidence that BC extract improved cognitive function, especially attention and memory, but this effect was not consistent across both trials. The researchers suggested that this may be due to the variability in cognitive performance among individuals and the influence of other factors such as mood and motivation.
The study did not find any significant effects of the test drinks on insulin secretion, gut hormone release, or appetite. The researchers noted that these outcomes may require longer-term interventions or higher doses of polyphenols or fiber to show any changes.
Implications for preventing type 2 diabetes
Type 2 diabetes is a chronic condition that affects millions of people worldwide and increases the risk of serious complications such as heart disease, kidney failure, and blindness. It is caused by a combination of genetic and environmental factors, but lifestyle changes such as eating a healthy diet, exercising regularly, and maintaining a healthy weight can help prevent or delay its onset.
The study suggests that consuming BC extract before meals could be a simple and natural way to lower blood sugar levels and potentially reduce the risk of developing type 2 diabetes. However, the researchers emphasized that this is not a substitute for following a balanced diet and other healthy habits.
They also pointed out that BC extract is not widely available as a food supplement and may have different effects depending on the source and quality of the berries. Therefore, they recommended further research to determine the optimal dose, duration, and formulation of BC extract for improving metabolic health.