Bioflavonoids are the water-soluble companions of ascorbic acid, usually found in the same foods. Vitamin P includes a number of components that work together—citrin, hesperidin, rutin, flavones, flavonals, and catechin and quercetin, which will also be discussed in Chapter 7, Accessory Nutrients. Their association with vitamin C is the reason that natural forms of vitamin C are more effective than are synthetic ascorbic acids without the bioflavonoids in the equivalent amounts.
Vitamin P was first discovered in 1936 by Hungarian scientist Dr. Albert Szent-Gyorgyi, who found it within the white of the rind in citrus fruits. It is contained mainly in the edible pulp of the fruits rather than in the strained juices. The letter P, for permeability factor, was given to this group of nutrients because they improve the capillary lining’s permeability and integrity—that is, the passage of oxygen, carbon dioxide, and nutrients through the capillary walls.
The bioflavonoids are easily absorbed from the intestinal tract, as is vitamin C. Some is stored in the body, though most of the excess is eliminated in the urine and perspiration.
Sources: The main source of bioflavonoids is the citrus fruits—lemons, grapefruits, oranges, and, to a lesser extent, limes. Rose hips, apricots, cherries, grapes, black currants, plums, blackberries, and papayas are other fruit sources of vitamin P. Green pepper, broccoli, and tomatoes are some good vegetable sources of bioflavonoids. The buckwheat plant, leaf and grain, is a particularly good source of bioflavonoids, especially the rutin component.
Functions: The bioflavonoids are helpful in the absorption of vitamin C and protect the multifunctional vitamin C molecule from oxidation, thereby improving and prolonging its functioning. Therefore, the bioflavonoids are indirectly, and possibly directly, involved in maintaining the health of the collagen that holds the cells together by forming the basement membranes of cells, tissues, and cartilage.
The main known function of the bioflavonoids is to increase the strength of the capillaries and to regulate their permeability. The capillaries link the arteries to the veins. They deliver oxygen and nutrients to the organs, tissues, and cells and then pick up carbon dioxide and waste and carry them through the veins and back to the heart. By its support of the capillaries, vitamin P helps to prevent hemorrhage and rupture of these tiny vessels, which could lead to easy bruising. Also, capillary strength may help protect us from infection, particularly viral problems. Bioflavonoids also can reduce the amount of histamine released from cells; quercetin is definitely strong in this function.
Uses: The main use of the bioflavonoids is to provide synergy in the utilization of vitamin C; therefore they contribute to many vitamin C applications—for example, the treatment of colds and flus. Bioflavonoids themselves are often supplemented for problems where improved capillary strength is needed, such as bleeding gums, easy bruising, and duodenal bleeding ulcers, which may be worsened by weak capillaries. The rutin component is particularly good for decreasing bleeding from weak blood vessels. In hemorrhoids, varicose veins, spontaneous abortions, excess menstrual bleeding (menorrhagia), postpartum hemorrhage, nosebleeds, the bleeding problems of diabetes, and generally during pregnancy, the bioflavonoids may be helpful in maintaining capillary health and reducing bleeding concerns. For women who have repeated spontaneous abortions or premature labor, supplementing citrus bioflavonoids—for example, 200 mg. three times daily—may be helpful in remedying these problems. Vitamin P has been used also in asthma, allergies, bursitis and arthritis, and eye problems secondary to diabetes and as protection from the harmful effects of radiation.
After all that, though, there is not much scientific evidence to support these clinical uses of bioflavonoids. Though they were touted very highly for a while, further research must be done to substantiate these claims.
Deficiency and toxicity: There is no known toxicity from any of the components of the bioflavonoids. Deficiency is fairly unlikely, although, as with vitamin C, an increased tendency to bruise or bleed is possible with vitamin P deficiency. Also, the protection that vitamin C gives against inflammatory problems, as in arthritis, may be lost when the bioflavonoids are not in the diet or supplemented. In my medical experience a question arises: if people respond to bioflavonoid (or any nutrient) supplementation, does that suggest a deficiency or depletion was present?
Requirements:There is no RDA for the bioflavonoids, perhaps because they naturally occur with vitamin C. When they are supplemented, 500 mg. bioflavonoids—containing 50 mg. rutin and 50 mg. hesperidin—is usually taken from one to three times daily. Supplements of 125 or 250 mg. of bioflavonoids are also commonly available and can be taken daily with the same frequency.