Thursday, July 26, 2007

Later we'll discuss sex and lower back pain

A breakthrough would be when you link intelligence to science writing--When I taught science writing I forbade the students from using the word breakthrough, mostly on grounds there are in fact very few real breakthroughs in science. The discovery of the helical structure of DNA is a breakthrough. The discovery of penicillin is a breakthrough. Breakthroughs come about four or five times a century. And the word is greatly overused by journalists who are trying to make their stories seem more important than they are, or by scientists doing likewise.

I’d like to add another word: link. The word link should be banned in all stories about nutrition, to be sure. What is linked today, isn’t linked tomorrow and even if there is a correlation that does not prove causation, so, so what? Journals are filled with stories linking something we eat to either something that will make us ill or to a cure or a prevention of whatever that was. And if you wait a year or two, someone will come up with the opposite results. Have some recent examples.

Vitamin C prevents or treat colds, or then, maybe it doesn't—Few substances have been studied more and the results are mixed. The general conclusion was that data were lacking to support the notion vitamin C prevents colds, but there was solid evidence it shortened their duration. Not now, at any rate. Sort of.

In a study published in the Cochrane Library, a meta-analysis of 30 published studies involving 11,350 people who took at least 200 milligrams of vitamin C daily, researchers reported that the substance did nothing to lower the risk of the common cold. There was a slight reduction in the duration and severity of cold symptoms compared to a placebo, but it was not statistically significant. There was no reason to take vitamin C daily, a Finnish researcher said, unless—here comes the almost part—you are exposed to short periods of extreme physical stress, like running around in sub-arctic temperatures. Vitamin C showed a slight benefit in that case. Note this was a meta-analysis, which I’m beginning to think is a procedure that is at the root of this problem. Meta-analysis are studies of studies, statistically measuring whether a bunch of studies prove anything. Statistically speaking, of course.

Diet sodas are better for you than the corn syrup kind—Wrong, you silly person. You’ve been reading too much of the medical literature. It turns out drinking as little as one soda can a day, diet or regular, is “associated” (that’s another word, a synonym for “linked”) with a 48% increased risk of metabolic syndrome, a precursor to heart disease and diabetes. Everyone agrees drinking the regular kind (corn syrup, which long ago replaced sugar) was linked to ill results but everyone thought diet soda was safe. The results, published in the journal Circulation, were puzzling even to the guys at Boston University to who did the study. They think it isn’t anything in the soda, just that it is sweet and hence, it changes dietary patterns toward sweetness, leading to obesity etc. This wasn’t a meta-analysis, but part of the Framingham study, which is much better. People who (like me) slugged down a Diet Coke a day also had a 31% chance of becoming obese; a 30% chance of having a larger waist line (like me), a 25% chance of developing high blood triglycerides or high blood sugar, and a greater risk of having too little of the good cholesterol. The soda industry pointed out, in this case accurately, that soda is 99%+ water and it was not likely anything in the rest could have that huge an effect. The study didn’t count all the other things these people did in their lives that could lead to the increases; the increase could easily have been coincidental to the diet soda.

But wait, there’s more.

Grapefruit is not good for you—All that vitamin C and stuff? Forgetaboutit. A study of 50,000 post-menopausal women found that eating as little as one quarter of a grapefruit daily raised the risk of breast cancer 30%. According to the British Journal of Cancer, the grapefruit inceased the levels of estrogen, which increased the risk. The problem with this study is that it relied on voluntary questionnaires, the least reliable source of data. And the objections above pertain here just as well.

Think we’re through?

Lycopene in tomatoes prevents cancer—Lycopene in tomatoes is not necessarily good for you. The Food and Drug Administration did a meta-analysis (here we go again) and found that lycopene, an anti-oxidant thought beneficial in preventing cancer (especially prostate cancer), doesn’t. Or, more precisely, the evidence is not statistically compelling. There is no evidence anything in tomatoes prevents cancer, the FDA reported, studying scores of tests that said there was. I had tomatoes for lunch.


Organic tomatoes are better for you than non-organic tomatoes—Yes. Really. We agree on something. A study in the Journal of Agricultural and Food Chemistry (I have a copy by the bed for leisure reading) says that organic tomatoes have a higher percent of flavonoids, antioxidants “linked” to preventing heart disease and cancer. The study is one of the first to substantiate claims that organic vegetables have an advantage over the factory-farmed stuff. They certainly taste better. The researchers, at UC Davis, think organic vegetables are better because of the availability of nitrogen in the soil.

Are you confused, dear reader? I would like to suggest a tomato and cheese pizza and a good cold glass of beer for lunch. Maybe a little popcorn. Might I recommend the couch? We can’t live forever.

Damn, I'm hungry.


Anonymous said...

Tomatoes probably do fight cancer. Lycopene, as a separated-out ingredient, does not. They were wrong to jump on lycopene -- but probably did it, hoping for a patent. (Anyone check patent database about claims like this?)

Grapefruit contains an ingredient which blocks the 'uptake' of a whole variety of things, many drugs included. It's a CYP but forgot which one. Shall we assume that it blocks the uptake of estrogen; therefore increasing levels?

Cochrane loves doing reviews. They are pretty much worth the paper they're printed on, or less. The question of 'same risk' vis-a-vis diet sodas and regular sodas seems to be the benzoate. Either sodium or potassium benzoate. There are some interesting things to learn about why this is probably a genuine problem.

Cochrane reviewing vitamin c. Uh huh, they're clueless. But taking a firm stand, nonetheless. Vitamin C -- like every other vitamin, mineral, amino acid, and so on -- requires other stuff, in order to be effective. Have to know all the 'rules' in order to make an intelligent judgment about efficacy.

Anonymous said...

And another thing--I read something like "X increases the risk 50%" and I wonder, 50% of what? From 1% to 1.5 %? From 20% to 30%? Generally I stop reading when the % thing pops up.


CW said...

Next, you'll have to report on frozen vegetables.

Anonymous said...

I don't believe that eating grapefruit is bad. blue silk