Do they really prevent illnesses? Are they effective in treating diseases?
Have you ever wondered what it takes for natural compounds to produce aroma, flavor and color in fruits and vegetables? The answer is flavonoids. Popular interest in flavonoids has been increasing due to the growing reputation of their antioxidant properties and associated benefits in disease prevention. The number of google searches related to flavonoids is 2.52 million, and there are more than 24,000 original publications about flavonoids on PubliMed, an online database focusing on medical research.
Flavonoids are a large family of phenolic compounds synthesized by plants as pigments for several purposes: to attract pollinators, to repel pests and to protect plant cells from ultraviolet radiation and the internal production of reactive oxygen types during photosynthesis. As a group, flavonoids are the type of phytochemicals generally associated with antioxidant benefits in plant foods. Health scientists believe that people acquire some of these benefits by eating plants rich in flavonoids, an area of ongoing analysis. Current research trends on flavonoids indicate that there are numerous potential health benefits associated with consuming diets rich in fruits and vegetables, even among healthy people, resulting in benefits for the cardiovascular system, brain, joints, skin and urinary tract system.
Many of the biological effects of flavonoids seem to originate from their ability to modify communication between cells, in addition to their antioxidant activity.
Scientists are studying flavonoids as biological response modifiers, a role which can alter the body’s response to viruses, allergens, bacteria, carcinogens (cancer producing agents), inflammatory agents and oxygen free radicals. Flavonoid intake may help prevent cancer in humans. Consumption of flavonoids may reduce the risk of neuro-vegetative diseases, such as Alzheimer’s or Parkinson’s.
There are 6 major classes of food flavonoids, and although they are related by the same chemical structure (phenols), there are at least 4,000 variations in the structure of flavonoids and therefore over 4,000 individual flavonoids in the plant kingdom. It is useful to group these compounds into 6 main classes, as their members present similar structures. The class names are also similar because their chemical structures are closely related:
- Anthocyanidins (anthocyanins structure): found in black, red and blue berries and grapes. Some are present in dark wines. Examples include: anthocyanidins: cyanidin, delphinidin, petunidine, peonidin, malvidin, pelargonidin.
- Flavanoles: found in black and green tea, berries and dark chocolate. Simple structures (nanometers) are called catechins, while multi-unit structures (polymers) are called proanthocyanidins, tannins, epigallocatechin and theaflavins. It may contain subgroups of ellagic and gallic acids. This class is also named flavan-3-ols.
- Flavanones: Found in citrus fruits (oranges, grapefruits, lemons). Members of this group include naringenin and hesperidin.
- Flavanols: Found in all plants with bright colors, such as berries, kale, broccoli and peppers. This group includes quercetin, kaempferol, myricetin, rutin and isorhamnetin.
- Flavones: apigenin and luteolin. Found in herbs, chamomile and parsley, as well as in roots like celery and radishes.
- Isoflavones: Found in soy products and its derivatives, like tofu or soy milk. Members of isoflavones include genistein and daidzein.
In test tubes (in vitro), flavonoids have demonstrated efficacy in eliminating free radicals in the human body. However, in concentrations in blood and within cells, flavonoids have shown lower levels than other antioxidants such as vitamin C, glutathione and melatonin. This is partly because flavonoids do not remain in blood or tissues and are filtered by the kidneys during urination or excretion. Scientists claim this characteristic makes flavonoids less bioavailable. Furthermore, it has been found that most circulating flavonoids are actually flavonoid substructures of the original molecule, after being degraded by stomach acids and metabolism.
Naturally, some of these new smaller flavonoid molecules have less antioxidant activity than the original molecule.
This refers to flavonoids consumed in a daily diet, demonstrating the importance of taking a supplement rich in flavonoids since dietary intake is not enough. The ideal complement should follow microencapsulation to prevent degradation from gastric acids and therefore be fully absorbed with all its properties.
Flavonoids affect communication between cells. Initially, it was thought that the main biological function of flavonoids was antioxidant, however, new scientific evidence indicates that flavonoids may modify the signaling activity between cells. Flavonoid concentrations necessary to change cellular signaling pathways are considerably lower than those required to fulfill various antioxidant functions.
Changes from cell to cell occur due to the signaling capability required by enzymes known as kinases to sensitize target proteins (receptors) in the host cell.
Cell culture experiments reported that flavonoids may have effects on chronic diseases by selective action of kinases, which means that flavonoids may alter receptor sensitivity in certain diseases, such as cancer, through the following mechanisms:
- Cancer cells depend on growth stimuli to expand and spread. Flavonoids can inhibit communication and signaling from one cell to another, preventing this growth.
- Cancer cells proliferate rapidly and lose their ability to undergo the normal signals that prevent apoptosis (cell death); flavonoids can inhibit the proliferation process and stimulate apoptosis.
- Cancer cells invade normal tissue, with the help of enzymes called metalloproteinases, flavonoids block the activities of these enzymes containing metals.
- Invasive tumors must also develop new blood vessels through a process known as angiogenesis to support their rapid growth, flavonoids inhibit angiogenesis.
- Tumor growth may depend on mechanisms of inflammation mediators to grow, proliferate and resist apoptosis. The anti-inflammatory properties of flavonoids are widely recognized. Ongoing investigations reveal additional characteristics of flavonoid biology in health and disease.
Author: Dr. Paul Gross.
References: Micronutrient Information Center, Lius Pauling Institute, Oregon State University. USA. Department of Agriculture, Data and Nutrient Laboratory.
: It is clear that consuming flavonoids can contribute to a healthy body and treat diseases such as cancer. However, it is very difficult to consume a diet rich in flavonoids due to the pace of modern life. The solution may lie in finding the right product with a combination of conjugated flavonoids, minerals and amino acids to provide us with the amounts of flavonoids necessary to prevent or treat cancer. It is also important that the group of flavonoids chosen are complementary and do not interfere with traditional treatments.[:]