Folate Cuts Inherited Colon Cancer Risk
Q: I know colon cancer often runs in families, but what's the folic acid connection I've been hearing about?
A: A person's colon cancer risk doubles if he or she has a parent or sibling with the disease. But the odds can change. Studies quite clearly show inheritable colon cancer risk may be markedly reduced by folic acid intake.
Data from the Nurses Health Study shows a diet high in folic acid and methionine (an essential amino acid) and low in alcohol, followed for at least five years, reduces colon cancer risk in people with a family history of colon cancer more than in those without an inheritable risk.4 Women with high-folate diets (>400 mcg/day) virtually eliminated their risk of inheritable colon cancer. A similar, large epidemiological study of Canadian women strengthens the folate connection.5 More than two glasses of alcohol (in this case, wine) appears to increase the inherited disease risk.
This is yet another example that gene predisposition is not as deterministic as once thought. With specific diet and lifestyle changes, people can modify their heredity risks.
Keep The Engine Oiled
Q: Most people probably don't get enough omega-3 oils, but how much should I be recommending?
A: It depends. People with conditions such as rheumatoid arthritis, ulcerative colitis or hypertriglyceridemia generally benefit from a combination of 3 g EPA and DHA. Remember, that's not 3 g of fish oils, but 3 g of the specific essential fatty acids eicosapentaenoic acid and docosahexaenoic acid.
Many people with such conditions don't get enough of these oils and so they don't benefit as completely from the oils' anti-inflammatory and triglyceride-modulating effects. For the average person, however, it appears a far smaller dose has health benefits.
For instance, a recent study shows relatively small amounts of omega-3 fatty acids in the diet prevent sudden death from heart attack. It appears men and women with no history of heart trouble can reduce their risk simply by eating fatty fish such as salmon or mackerel twice a week. Research from the Physicians Health Study shows that men eating the omega-3 fatty acids in fatty fish can reduce their sudden-death risk by 80 percent.1 The Nurses Health Study shows eating the same fatty acids cut a woman's risk of heart disease by 33 percent.2
Neither study examined the benefits of fish oil supplements, but another report seems to address them. It shows that, in men who had recent heart attacks, supplementing with 1 g/day of omega-3 fatty acids cut the risk of death after heart attack nearly in half.3
Calcium OK For Kidney Stones
Q: Should people with calcium oxalate kidney stones avoid calcium in their diets?
A: This question has been bandied about in the medical literature for some time, and I think there's a lot of misinformation on the subject.
Once someone has a kidney-stone attack, there's a 50 percent chance a second stone will form in five to seven years, so prevention is extremely important. Although a low-calcium diet is often still recommended to prevent this type of recurrent stones, long-term data on the efficacy of such diets are lacking, and the rationale for suggesting them is weak.
A recent study shows low-calcium diets are neither necessary nor effective in preventing repeat calcium oxalate kidney stones. It demonstrates instead that a diet with ample calcium but reduced animal protein and salt works better.
Researchers compared the effects of two diets in 120 men with recurrent calcium oxalate kidney stones.6 Sixty men were assigned to a diet containing a normal amount of calcium but reduced animal protein (52 g/day) and salt. The other 60 men were assigned to a traditional low-calcium diet. After five years, 12 men on the normal-calcium diet and 23 on the low-calcium diet had relapses. Thus, a low-protein and low-salt diet combined with normal calcium intake provided more protection against repeat kidney stones than the traditional low-calcium diet did.
Considering that other epidemiological studies demonstrate low calcium intake actually increases the incidence of kidney stones, this research strongly suggests people with kidney stones should avoid low-calcium diets.7
Dan Lukaczer, N.D., is director of clinical research at the Functional Medicine Research Center, a division of Metagenics Inc., in Gig Harbor, Wash.
1. Albert CM, et al. Blood levels of long-chain n-3 fatty acids and the risk of sudden death. N Engl J Med 2002;346(15):1113-8.
2. Hu FB, et al. Fish and omega-3 fatty acid intake and risk of coronary heart disease in women. JAMA 2002;287(14):1815-21.
3. Marchioli R, Barzi F, Bomba E, et. al. (2002) Early protection against sudden death by n-3 polyunsaturated fatty acids after myocardial infarction: time-course analysis of the results of the Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto Miocardico (GISSI)-Prevenzione. Circulation 105(16):1874-5.
4. Fuchs CS, et al. The influence of folate and multivitamin use on the familial risk of colon cancer in women. Cancer Epidemiol Biomarkers Prev 2002;11(3):227-34.
5. Terry P, et al. Dietary intake of folic acid and colorectal cancer risk in a cohort of women. Int J Cancer 2002;97(6):864-7.
6. Borghi L, et al. Comparison of two diets for the prevention of recurrent stones in idiopathic hypercalciuria. N Engl J Med 2002;346(2):77-84.
7. Martini LA. Stop dietary calcium restriction in kidney stone-forming patients. Nutr Rev 2002;60(7 Pt 1):212-14.
Natural Foods Merchandiser volume XXIII/number 10/p. 84