Scientists from King’s College London found that drinking blackcurrant extract could decrease blood sugar and insulin levels after a meal.
Blackcurrants are a highly nutritious superfood. These tiny berries have a sweet–tart taste and are packed with nutrients and antioxidants. Blackcurrants contain four times more vitamin C than oranges and twice as many antioxidants as blueberries.
The body uses vitamin C to metabolize protein and to form collagen, which is essential for skin care and anti-aging.
Blackcurrants are also rich in anthocyanins, which may help inhibit postprandial glycemia.
Anthocyanins are the pigments responsible for red, purple, and blue colors in fruits and vegetables. Berries, currants, grapes, and some tropical fruits contain high levels of anthocyanins.
Postprandial hyperglycemia refers to an exaggerated rise in blood sugar after a meal.
In people without diabetes, the pancreas releases insulin constantly and increases insulin production after meals as blood glucose rises.
A strong spike in blood sugar after eating can trigger inflammation and oxidative stress, which may contribute to artery stiffness and raise the risk of heart disease.
In the study, researchers examined the dose-dependent effects of blackcurrant extract on post-meal blood sugar levels. They tested 23 middle-aged men and women.
Participants consumed low-sugar fruit drinks that contained either 150 mg, 300 mg, or 600 mg total anthocyanins from blackcurrant extract, or a control drink without blackcurrant extract, immediately before a high-carbohydrate meal.
The team then measured blood sugar, insulin, gut hormone responses, and arterial stiffness before and after the fruit drinks.
They found that when participants drank the fruit drink containing the highest level of blackcurrant extract, their blood sugar levels dropped strongly 30 minutes later. Insulin levels were similarly reduced.
In addition, gut hormone levels were strongly reduced two hours after consuming the high-level blackcurrant extract.
These findings suggest that consuming about 100 g of blackcurrants could help reduce blood sugar, insulin, and gut hormone levels after meals.
The researchers say that including blackcurrants in the diet may support both heart and metabolic health.
One limitation of the study is that the researchers did not measure blood levels of anthocyanins or their metabolites.
The team notes that such data could help verify the benefits of blackcurrants on vascular function and blood pressure. Future studies may address this.
The research is published in The Journal of Nutritional Biochemistry and was conducted by Monica L Castro-Acosta et al.
