When it comes to citrus and the goodness of bioflavonoids, recent research says that the more bitter, the better. It’s the bitter tasting flavonoids that impart most of the health benefits, such as anti-inflammatory and cardio-protective properties. The study by Chinese researchers involved a large scale review, with the subtitle A comprehensive review of the metabolism of citrus flavonoids and their binding to bitter taste receptors.
Ironically, as the researchers of a new paper published by the Institute of Food Technologists (IFT), it is also the bitterness that most food manufacturers look to remove from citrus when processing foods.
Citrus flavonoids & bitter taste receptors
Citrus, as the researchers note, is an important part of our diet as one of the major sources of flavonoids in our daily diet. Flavonoids impart antioxidant, anticancer, and anti-inflammatory properties, as well as protecting against cardiovascular disease.
In citrus fruits, the most abundant bitter flavonoids are limonin and flavanone compounds. Flavonols are secondary metabolites, many of which are also bitter tasting, including quercetin. In the plants, flavonols protect the leaves against UV damage, as well as helping to regulate the plant’s growth.
Earlier studies have demonstrated that those pharmaceutical properties may just be related to the way the flavonoids are bound to bitter taste receptors.
Bitter taste receptors, also called T2Rs, are located in the taste buds. There is a growing body of research, however, that indicates they are also to be found throughout the body, in the digestive, respiratory, and genitourinary systems, and in specific cells within the brain and immune system. Outside of the tongue, they seem to have various specialized mechanisms that function in the body.
That research suggests that medicines and other compounds which we experience as having a bitter taste, in turn act on the T2R receptors in these specific areas of the body through what is called downstream signaling.
The review study backs up other recent research that links bitterness to flavonoids and their benefits.
As the review study notes, there is very little research on how those mechanisms actually work. If that were better understood, they write, it would be possible to modify the design of natural citrus flavonoids to make them easier to use in a pharmaceutical basis.
The moral of the story: don’t be shy of the bitter taste. It’s what’s good for you.