In the world of nutrition, few terms are as frequently misunderstood and incorrectly interchanged as "bioflavonoids" and "flavonoids." Many consumers encounter these words on supplement bottles or in health food articles and assume they refer to distinct classes of compounds. The truth is much simpler: the terms describe the same group of beneficial plant compounds. The real difference is largely historical and a matter of modern nomenclature, where "flavonoid" is the scientifically accepted term.
The Origin of the Terminology
The story of this confusion begins in the 1930s with Albert Szent-Györgyi, the Nobel Prize-winning scientist who discovered vitamin C. In his early research, he isolated a group of compounds from oranges that appeared to enhance the absorption and activity of vitamin C. Believing they were a new class of vitamins, he named them "vitamin P," with the "P" standing for permeability, as they were thought to affect capillary permeability.
Over time, it became clear that these compounds, and the thousands of related compounds found in other plants, were not true vitamins—essential nutrients that the body cannot synthesize. Therefore, the name was dropped from scientific classification by the 1980s. The broader term "bioflavonoids"—with the prefix "bio" indicating their biological origin—was used for a period to refer to this group of bioactive compounds from plants. However, in modern botany, chemistry, and nutritional science, the term has been streamlined and refined. Today, the class of compounds is almost universally referred to as flavonoids. The term bioflavonoid persists primarily in dietary supplement marketing and older health-related texts.
What Exactly are Flavonoids?
Flavonoids are a diverse and widespread group of phytonutrients, or plant-based chemical compounds, that are responsible for the vibrant colors in many fruits, vegetables, and flowers. They are a subclass of a larger group of plant compounds known as polyphenols.
Chemical Structure
All flavonoids share a common chemical structure consisting of a 15-carbon skeleton arranged in a C6-C3-C6 configuration. This consists of two aromatic benzene rings (A and B) connected by a three-carbon chain that forms a central oxygenated heterocyclic ring (C). Slight variations in this structure, particularly in the C ring and the attachment of the B ring, result in the different subclasses of flavonoids.
The Major Subclasses of Flavonoids
The biological activity and food sources of flavonoids vary significantly depending on their specific chemical subclass. The most dietarily significant subclasses are:
- Flavanols: Found in teas (catechins, theaflavins), cocoa products, and apples. They are known for their strong antioxidant properties and benefits for cardiovascular health.
- Flavonols: Present in onions, kale, berries, and tea, this subclass includes quercetin and kaempferol. They offer antioxidant, anti-inflammatory, and potential anticancer effects.
- Flavanones: Abundant in citrus fruits like oranges and grapefruit, this group includes hesperidin and naringenin. Flavanones are known for their antioxidant and anti-inflammatory properties, with some showing positive effects on cardiovascular health.
- Flavones: Found in herbs like parsley and thyme, as well as celery, this subclass contains compounds like apigenin and luteolin. They have potent anti-inflammatory effects.
- Anthocyanidins: These are the pigments responsible for red, blue, and purple colors in fruits and vegetables such as berries and red grapes. They are associated with cardiovascular health and potentially improving cognitive function.
- Isoflavones: Primarily found in legumes like soy, isoflavones such as genistein and daidzein are known for their phytoestrogen activity.
Bioflavonoids vs. Flavonoids: A Clarification
The fundamental difference, or lack thereof, is summarized below:
| Feature | Flavonoids | Bioflavonoids |
|---|---|---|
| Definition | A large class of plant secondary metabolites, and a subclass of polyphenols. | A historical and non-specific term for flavonoids, also known as "vitamin P" in early research. |
| Usage | The current, scientifically accepted term used in modern botany, chemistry, and nutrition. | A dated synonym that persists in some supplement marketing and older texts. |
| Scope | Encompasses a vast array of subclasses, such as flavanols, flavones, and anthocyanidins. | Refers to the same broad class of compounds but is not a recognized classification in modern science. |
| Focus | Specifies different subclasses with unique properties, allowing for precision in nutritional research. | A generalized term that does not distinguish between the various types or their specific effects. |
The Nutritional Role of Flavonoids
Flavonoids are prized in nutrition for their numerous health-promoting properties. Their most well-known function is their potent antioxidant activity, which helps neutralize harmful free radicals in the body. This ability to combat oxidative stress is linked to a reduced risk of chronic diseases such as cancer, cardiovascular disease, and neurodegenerative disorders. Flavonoids also exert strong anti-inflammatory effects, which can mitigate the risk of conditions linked to chronic inflammation.
For example, studies have linked higher intake of certain flavonoids to lower blood pressure and improved cholesterol levels, supporting cardiovascular health. Additionally, particular flavonoids may help modulate immune function, support skin health, and have shown promise in improving cognitive function and memory, especially as people age. The best way to benefit from these compounds is through a balanced diet rich in a wide variety of colorful fruits and vegetables, rather than relying solely on supplements. Consuming flavonoids from food sources ensures a broader spectrum of these beneficial phytonutrients and a higher overall nutritional intake.
Conclusion: Terminology Simplified
In essence, there is no substantive difference between bioflavonoids and flavonoids; they refer to the same family of beneficial plant compounds. The term "bioflavonoid" is an anachronistic holdover, while "flavonoid" is the standard scientific term used today. The more critical distinction from a nutritional perspective is understanding the different subclasses of flavonoids and the diverse array of foods that contain them. By focusing on a diet rich in a variety of fruits, vegetables, and other plant-based foods, you can ensure a consistent intake of these powerful antioxidants and reap their wide-ranging health benefits.
Learn more about flavonoid types and their sources from the Linus Pauling Institute at Oregon State University: https://lpi.oregonstate.edu/mic/dietary-factors/phytochemicals/flavonoids.
