Certain types of purple vegetables and tubers may be more effective against type 2 diabetes according to a study.
Anthocyanins are natural compounds responsible for the red-orange and blue-violet colors of many fruits, vegetables and tubers. Research has shown that anthocyanins have beneficial effects on the gut microbiome, energy metabolism, and inflammation. A recent literature review highlights how purple vegetables and tubers can help prevent and manage type 2 diabetes through their action on energy metabolism, inflammation and gut microbiota.
Research also indicates that acylated anthocyanins, found in vegetables such as red cabbage and purple sweet potato, may be superior to non-acylated anthocyanins, found in blackberries and blackcurrants, in terms of of antidiabetic properties.
Normally, a hormone called insulin moves glucose (sugar) from the blood into cells, where it is used for energy. But in type 2 diabetes, the body doesn’t use or produce insulin properly, and glucose builds up in the blood instead of being used by cells. If not properly managed, diabetes can ultimately cause many health problems, including cardiovascular disease, high blood pressure, nerve damage, eye damage, and loss of vision, kidney disease and foot problems.
Although a variety of factors can increase the risk of developing type 2 diabetes, including a family history of diabetes, research has shown that a diet rich in fruits and vegetables can delay or prevent the onset of diabetes and improve well-being. be people with health problems related to diabetes. The benefits associated with fruits and vegetables are attributed to their high concentration of polyphenols. A particular class of polyphenols, the anthocyanins, is responsible for the red-orange to blue-violet color of plants.
Studies conducted in the United States and Finland have shown that eating foods high in anthocyanins, especially berries, reduces the risk of type 2 diabetes. Many studies have been conducted to better understand the antidiabetic properties of anthocyanins. A new review article published in the Journal of Agricultural and Food Chemistry summarizes the effects of anthocyanins on the gut microbiome, energy metabolism, and inflammation, with a particular focus on acylated anthocyanins.
Acylated and non-acylated anthocyanins
Anthocyanins are divided into two categories based on their molecular structure: acylated and non-acylated. Acyl anthocyanins have a chemical group called the “acyl group” (composed of a carbon atom and an oxygen atom doubly bonded to each other, with a single bond to another carbon atom), what non-acylated anthocyanins lack.
Compared to unacylated anthocyanins, acylated anthocyanins are more stable and more resistant to digestion. For this reason, they are not digested and absorbed in the stomach and upper intestine, and pass through the colon, where they are extensively broken down by intestinal microorganisms. Elderberry, blackberry, and black currant mostly contain unacylated anthocyanins, while acylated anthocyanins are found in red radish, purple corn, black carrot, red cabbage, and purple sweet potato.
Studies of the two types of anthocyanins differ in their design and analytical methods, making it difficult to draw clear conclusions about differences in biological activity.
However, this study suggests that acylated anthocyanins may be superior to non-acylated anthocyanins in terms of antidiabetic properties. Purple potatoes (rich in acylated anthocyanins) are also high in resistant starch and other compounds that may contribute to their anti-diabetic effects. The berries (rich in unacylated anthocyanins) contain a significant amount of natural sugar that can negate some of the anti-diabetic effects of anthocyanin.
Anthocyanins promote gut health
Researchers have studied the effects of various anthocyanins on bacteria living in the gut (or gut microbiome) using animal models. In a mouse study, unacylated anthocyanins from black rice increased the abundance of certain gut bacteria, including Akkermansia muciniphila. A. muciniphila has been shown to stimulate insulin secretion and improve glucose metabolism in mice with type 2 diabetes. Acylated anthocyanins from various sources, such as purple sweet potato, have also been shown to and Concord grape, affect the gut microbiome by promoting the growth of beneficial bacteria, inhibiting the growth of harmful bacteria, and increasing the production of short-chain fatty acids, which are beneficial for gut health and blood sugar control .
Anthocyanins lower blood sugar
One of the pharmacological effects of anthocyanins is the inhibition of carbohydrate-digesting enzymes, which leads to a reduction in blood sugar. Additionally, research has shown that anthocyanins activate glucose and lipid metabolism pathways in the liver and muscle, which also helps lower blood sugar.
In one study of diabetic mice allowed to feed freely for two weeks, those given a mulberry fruit extract containing non-acylated anthocyanins had blood sugar levels approximately 30% lower at the end of the study. to that of unsupplemented mice. Similarly, another study showed that administration of acylated anthocyanin extracts of purple sweet potato to diabetic mice for 4 weeks at a daily dose of 500 mg/kg body weight resulted in a significant reduction in blood sugar. and an improvement in insulin insensitivity in the treated groups.
The hypoglycemic effects of anthocyanins have been attributed to the activation by anthocyanins of the AMPK (AMP-activating protein kinase) and PI3K/AKT (phosphoinositide 3 kinase/protein kinase B) pathways, which are crucial for glucose and lipid metabolism. .
However, most of the studies cited in the review used anthocyanin-rich extracts, rather than purified anthocyanins, so other polyphenols and flavonoids present in the extracts could have had synergistic effects. Most flavonoids can also affect carbohydrate absorption by inhibiting carbohydrate-digesting enzymes and binding to sugars, thus preventing their absorption.
Anthocyanins reduce inflammation
Consuming carbohydrates or fats triggers a short-term inflammatory immune response. Normally, the inflammation goes away quickly, but if it doesn’t, it can become chronic. Chronic inflammation can harm cells in the pancreas that secrete insulin, which can lead to obesity, insulin resistance, and type 2 diabetes. In studies with diabetic mice, dietary supplementation with unacylated and acylated anthocyanins reduced inflammation. This reduction in inflammation decreases insulin resistance and improves glucose metabolism in diabetes. Several studies have shown that anthocyanins exert an anti-inflammatory effect by inhibiting the NF-κB pathway of inflammation. Other studies have shown that unacylated anthocyanins activate the Nrf2 pathway, which helps produce antioxidant proteins to protect against inflammation or injury-induced oxidative damage.
Key points to remember
Recent findings on the antidiabetic effects of anthocyanins suggest that eating more fruits and vegetables rich in anthocyanins may be beneficial for the prevention and management of type 2 diabetes.
Although it is difficult to draw clear conclusions about differences in biological activity between the two types of anthocyanins due to differences in study design and analytical methods, acylated anthocyanins may have more benefit. potential in regulating energy metabolism, inflammation and gut microbiota in type 2 diabetes compared to unacylated anthocyanins.
