You may eat oranges and other citrus fruits and drink their juice because of their vitamin C, but they also contain other important nutrients. For example, at least 170 phytochemicals have been identified so far in orange juice. They are also rich in polyphenols, which include a wide range of flavonoids and related compounds, many with beneficial effects and nearly all with tongue-twisting names. Earlier research had also suggested that flavonoids such as those in citrus can lower the risk of stroke.
Oxidation increases artery-damaging deposits and thus promotes atherosclerosis.
This study was odd, however, since this effect occurred only in people drinking at least three glasses of juice a day. No other food is known to have a significant effect on HDL, so further studies will be needed to confirm this finding. A Dutch study found that citrus fruit, probably because of its supply of the B vitamin folic acid, lowers blood levels of homo-cysteine, a substance that may increase the risk of heart disease. Citrus skin contains D-limonene and coumarins, which leach into the juice. Coumarins help reduce blood clotting and may also have anti-cancer capacity.