And choline is mainly found in red meat, eggs, dairy products etc. So should we all become vegetarians?
There are heaps of things that could be said about this but the reaction of the medical researchers and commentators is sure amusing. The authors themselves draw the sort of conclusion that should be drawn in EVERY epidemiological study. They conclude that the effect they found "could represent effects of other components in the foods from which choline was derived". Correlation is not causation, in other words.
The editors of the journal also showed unusual humility: "Clearly, one-carbon metabolism and its role in [cancer development] is more complicated than originally anticipated, and our understanding of the underlying mechanisms is probably incomplete. More research, and caution in developing public health policy and guidance, is warranted"
More "caution in developing public health policy" from epidemiological findings? Long overdue. There should be more of it.
Another VERY interesting comment from them: "Other reasonable hypotheses about one-carbon metabolism and colorectal carcinogenesis, based on our current understanding of the biochemistry and underlying mechanisms, have also not been proven correct. In a recently published placebo-controlled randomized clinical trial among 1021 men and women with a recent history of colorectal adenoma, supplemental folic acid at 1 mg/d for up to 6 years did not reduce the incidence of subsequent colorectal adenomas and might have increased it.
WHOA! That folate that everybody gets compulsorily added to their bread did no good and seems to have done harm?? And do we see a double blind controlled study contradicting epidemiological inferences?? Who would have believed it!
They go on to admit that two animal studies have shown that folate INCREASES cancer. Aren't you glad that your government is dosing you up with the stuff and giving you no say in the matter?
OK. I will not gloat any further. I am reluctant to let the wiseheads off the hook but I don't actually think that the particular study below tells us anything much at all. Its main value has been to squeeze out from the know-alls the long overdue admissions and cautions about folate noted above. It's certainly a pity that such admissions are so infrequent, however.
What they all seem to be overlooking is that the study is about REPORTED food intake. And we know how fraught that can be. The nurses who were surveyed would all be acutely aware that eating lots of meat, dairy and eggs is NAUGHTY, according to the current wisdom. So many would have understated what they ate in that department. So what the study really shows is that REBELLIOUS or especially honest people get more polyps. It probably had nothing to do with their choline intake at all.
So where do we go from there? Who is it who would disregard official dietary advice and eat what they like? Easy: Working class people. Nurses come from all social backgrounds and there would be plenty who would happily wrap themselves around a Big Mac with no guilt at all. And, as we repeatedly find, the workers have more health problems generally for all sorts of reasons, including not only such things as a riskier lifestyle but genetic differences as well. So all we have at the end of this study is another demonstration of that old truth: The workers have poorer health in all sorts of ways.
But the addition of folate to our bread is more and more looking like an iatrogenic disaster to come. I think I should note that I have previously reported that the addition of folate to bread seems to have caused an upsurge in bowel cancer.
Dietary Choline and Betaine and the Risk of Distal Colorectal Adenoma in Women
By Eunyoung Cho et al.
Background: Choline and betaine are involved in methyl-group metabolism as methyl-group donors; thus, like folate, another methyl-group donor, they may be associated with a reduced risk of colorectal adenomas. No epidemiologic study has examined the association of intake of these nutrients and colorectal adenoma risk.
Methods: We investigated the relationship between intakes of choline and betaine and risk of colorectal adenoma in US women enrolled in the Nurses' Health Study. Dietary intake was measured by food-frequency questionnaires, and individual intakes of choline and betaine were calculated by multiplying the frequency of consumption of each food item by its choline and betaine content and summing the nutrient contributions of all foods. Logistic regression models were used to calculate adjusted odds ratios (as approximations for relative risks) and 95% confidence intervals (CIs) of colorectal adenoma. All statistical tests were two-sided.
Results: Among 39246 women who were initially free of cancer or polyps and who had at least one endoscopy from 1984 through 2002, 2408 adenoma cases were documented. Increasing choline intake was associated with an elevated risk of colorectal adenoma; the multivariable relative risks (95% CIs) for increasing quintiles of intake, relative to the lowest quintile, were 1.03 (0.90 to 1.18), 1.01 (0.88 to 1.16), 1.23 (1.07 to 1.41), and 1.45 (1.27 to 1.67; Ptrend less than .001). Betaine intake had a nonlinear inverse association with colorectal adenoma; the multivariable relative risks (95% CIs) for increasing quintiles of intake were 0.94 (0.83 to 1.07), 0.85 (0.75 to 0.97), 0.86 (0.75 to 0.98), and 0.90 (95% CI = 0.78 to 1.04; Ptrend = .09). Among individual sources of choline, choline from phosphatidylcholine and from sphingomyelin were each positively related to adenoma risk.
Conclusions: Our findings do not support an inverse association between choline intake and risk of colorectal adenoma. The positive association between choline intake and colorectal adenoma that we observed could represent effects of other components in the foods from which choline was derived and should be investigated further.
JNCI Journal of the National Cancer Institute 2007 99(16):1224-1231
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