Dietary Supplement. Highest in purity. TwinLab offers the highest bioflavonoid content concentrated from fresh lemons, oranges, grapefruits, limes and tangerines, along with the greatest number of individual bioflavonoids available from any manufacturer. Unlike other products, each production batch of TwinLab bioflavonoids is assayed by independent laboratories and tested by HPLC (High Pressure Liquid Chromatography) to measure and assure the true content of the individual and total bioflavonoids. TwinLab C-Plus Citrus Bioflavonoid Caps are easier to swallow and assimilate. Contains pure crystalline Vitamin C and the purest source of citrus bioflavonoids available. No tablet coatings, binders, granulators, disintegrators, colors, flavors, sweeteners or time release excipients. Free of corn, yeast, wheat, milk and egg products. No added sugar, salt or preservatives. This product is manufactured at our own state of the art facility.