Apples again:

Having badmouthed apples just a few months ago I now keep running across reasons to eat more of them. I mistakenly said that I didn't know if the saying, 'an apple a day kept the doctor away' had any validity.

It was only a matter of days before I read that apples are an excellent source of glucaric acid, a chemical which encourages detoxification of carcinogens and potentially decreases cancer risk. Now I've stumbled into another piece about apples.

A Finnish study several years ago looked at the relationship between dietary flavonoids and cancer risk. People who ate the most flavonoids had a 20% decrease in overall cancer risk. If they were smokers, high flavonoid consumption had a greater benefit, decreasing risk by 45%. By far the biggest single food to have an effect were apples. Apples decreased cancer rates by 87%. [1] The presumed explanation for this effect is that apples contain large amounts of quercetin. This isn't the only study which points to benefits from quercetin. Quercetin is usually thought of for its potent anti-inflammatory, anti allergy, and antioxidant activity but it has a role in preventing and treating cancer. In vitro research shows quercetin has significant activity against a range of cancer cell lines, (including breast, ovarian, stomach, skin, colon, and brain cancers) causing the cells to either differentiate into healthy cells or to self destruct (apoptosis). [2,3,4,5,6,7] It appears that quercetin increases the effectiv eness of other cancer treatments. [8.9] It may protect healthy cells from oxidative damage during treatment.[10,11]

Only a fraction of the quercetin taken orally is absorbed. [12] Common practice is to take equal amounts of Bromelain with quercetin to enhance its activity probably by increasing absorption. It stands to reason that in situations where absorption isn't necessary, quercetin is already strongly indicated. Such situations are preventing and treating cancers of the stomach, intestine, and colon. As we have a great deal of clinical experience using quercetin for treating internal systemic conditions such as rheumatoid arthritis and allergies, we have good reason to believe that it is absorbed and does act in the body in a manner predicted by in vitro research. Aside from apples the best dietary source of quercetin appears to be onions.

Onion Soup:
2 pounds of large onions
1/4 cup olive oil
4 cups soup stock ( beef, chicken, turkey carcass, or vegetable) [Leftover wine may be substituted for up to one cup of the stock.)
salt, pepper, and a touch of ginger to taste
5 slices of french bread toasted
grated cheese or parmesan cheese

Slice the onions into 1/8 inch rings and cook slowly in the oil until lightly browned. add stock and boil for a couple of minutes. Season to taste. Pour Soup into cups or plates, float the toast and cover with a generous helping of cheese. Broil just long enough to brown the cheese and serve.

References:
1. Knekt P, Jarvinen R, Seppanen R, et al. Dietary flavonoids and the risk of lung cancer and other malignant neoplasms. Am J epidemiol 1997; 146:223-30
2. Huang Y, Hwang J, Lee P, Ke F, Huang J, Huang C, Kandaswami C, Jr EM, Lee M. Effects of luteolin and quercetin, inhibitors of tyrosine kinase, on cell growth and metastasis-associated properties in A431 cells over expressing epidermal growth factor receptor. Br J Pharmacol 1999 Nov;128(5):999-1010
3. Yoshida M, Sakai T, Hosokawa N, Marui N, Matsumoto K, Fujioka A, Nishino H, Aoike A. The effect of quercetin on cell cycle progression and growth of human gastric cancer cells FEBS Lett 1990 Jan 15;260(1):10-3
4. Uddin S, Choudhry MA. Quercetin, a bioflavonoid, inhibits the DNA synthesis of human leukemia cells. Biochem Mol Biol Int 1995 Jul;36(3):545-50
5. Richter M, Ebermann R, Marian B . Quercetin-induced apoptosis in colorectal tumor cells: possible role of EGF receptor signaling.
6. Csokay B, Prajda N, Weber G, Olah E. Molecular mechanisms in the antiproliferative action of quercetin. Life Sci 1997;60(24):2157-63
7. Singhal RL, Yeh YA, Praja N, Olah E, Sledge GW Jr, Weber G Quercetin down-regulates signal transduction in human breast carcinoma cells.Biochem Biophys Res Commun 1995 Mar 8;208(1):425-31
8. Yeh YA, Herenyiova M, Weber G Quercetin: synergistic action with carboxyamidotriazole in human breast carcinoma cells. Laboratory for Experimental Oncology, Indiana University School of Medicine, Indianapolis 46202-5200, USA.
9. Li W, Shen F, Weber G. Ribavirin and quercetin synergistically down regulate signal transduction and are cytotoxic in human ovarian carcinoma cells. 1999;11(5):243-7 The Walther Oncology Center and the Laboratory for Experimental Oncology, Indiana University School of Medicine, Indianapolis 46202-5119, USA
10. Kitamura M, Ishikawa Y. Oxidant-induced apoptosis of glomerular cells: intracellular signaling and its intervention by bioflavonoid. Kidney Int 1999 Oct;56(4):1223-9
11. Yokoo T, Kitamura M. Unexpected protection of glomerular mesangial cells from oxidant-triggered apoptosis by bioflavonoid quercetin. Am J Physiol 1997 Aug;273(2 Pt 2):F206-12
12. Hollman PCH, et al., Absorption of dietary quercetin glycosides and quercetin in healthy ileostomy volunteers. Am J Clin Nutr 62, 1276-1282, 1995.