Monday, January 22, 2007

Trans fats make you infertile?

Popular summary below followed by the journal abstract and comment

Fats hidden in thousands of foods can harm a woman's chance of having a baby, scientists say. A study by scientists from Harvard University's School of Public Health says the fats can increase the risk of fertility problems by 70 per cent or more. And eating as little as one doughnut or a portion of chips a day can have a damaging effect. The scientists behind the study have advised women who want to have a baby to avoid the fats, known as trans fats. They are used in thousands of processed foods, from chocolate to pies, as well as takeaway meals. They have no nutritional value [Really?? A selective definition of nutrition, I fear], but are included simply to extend the shelf life of food.

It is very difficult to know the precise amount of trans fats in any food because it does not have to be put on the label. The fats are found naturally in some red meat and dairy products, but most are produced artificially in a high-temperature process called hydrogenation, which turns oil into solid fat.

Nutritionist Rosemary Stanton said the study was more evidence labelling should be compulsory. "If you compel manufacturers to label products, evidence shows they will want to say their products have 'no trans fats'. And this will stop them using these bad fats," Ms Stanton said. Other studies showed that trans fats were bad for pregnant women because they stopped the benefits of omega-3 fatty acids reaching an unborn child's brain, she said. Women should be wary of processed canola oil used in many Australian foods such as crisps, pastries and crackers, she said.

The US study's lead researcher, Dr Jorge Chavarro, said the findings suggested that women wanting to conceive should watch their trans fat consumption, as well as give up smoking and maintain a healthy weight.


Journal abstract

Dietary fatty acid intakes and the risk of ovulatory infertility

By Chavarro J.E. et al.

BACKGROUND: Pharmacologic activation of the peroxisome proliferator-activated receptor gamma (PPAR-gamma) improves ovulatory function in women with polycystic ovary syndrome, and specific dietary fatty acids can affect PPAR-gamma activity.

OBJECTIVE: The objective of the study was to assess whether the intakes of total fat, cholesterol, and major types of fatty acids affect the risk of ovulatory infertility.

DESIGN: We conducted a prospective cohort study of 18 555 married, premenopausal women without a history of infertility who attempted a pregnancy or became pregnant between 1991 and 1999. Diet was assessed twice during follow-up by using a food-frequency questionnaire.

RESULTS: During follow-up, 438 incidents of ovulatory infertility were reported. In logistic regression analyses, intakes of total fat, cholesterol, and most types of fatty acids were not related to ovulatory infertility. Each 2% increase in the intake of energy from trans unsaturated fats, as opposed to that from carbohydrates, was associated with a 73% greater risk of ovulatory infertility after adjustment for known and suspected risk factors for this condition [relative risk (RR) = 1.73; 95% CI: 1.09, 2.73]. Obtaining 2% of energy intake from trans fats rather than from n-6 polyunsaturated fats was associated with a similar increase in the risk of ovulatory infertility (RR = 1.79; 95% CI: 1.11, 2.89). In addition, obtaining 2% of energy from trans fats rather than from monounsaturated fats was associated with a more than doubled risk of ovulatory infertility (RR = 2.31; 95% CI: 1.09, 4.87).

CONCLUSION: trans Unsaturated fats may increase the risk of ovulatory infertility when consumed instead of carbohydrates or unsaturated fats commonly found in nonhydrogenated vegetable oils.



This is a long way from a double-blind control-group study. It is a cheap and nasty study based on a self-report questionnaire -- with all the limitations that implies. The major deficit would appear to be a failure to allow for social class. Poor people probably both eat more fast food and are more ready to acknowledge it -- thus being rated as big trans-fat consumers. And poor people tend to have more health problems. Surveys such as this do have the potential benefit of making meaningful sampling easier but there is no mention of sampling -- which makes the results of unknowable generalizability

Chinese herbs offer hope to fight disease

The first large-scale screening of herbs commonly used in traditional Chinese medicine reveals they contain thousands of compounds with the potential to fight diseases from cancer to HIV-AIDS and conditions such as erectile dysfunction and high blood pressure. The compounds are promising "candidates" for new drugs, pharmaceutical chemist David Barlow and his colleagues at King's College London claimed.

Dr Barlow's group discovered 8264 chemical compounds in the 240 plants studied. And 62per cent of them contained at least one potential disease-fighting biochemical, with 53 per cent containing two or more. Some, such as maidenhair and skullcap, were packed with five or more active ingredients.

The team will report in an upcoming edition of the American Chemical Society's Journal of Chemical Information and Modelling that it found almost 2600 compounds that could be used to fight a host of ailments. Among them were pain, inflammation, dementia, obesity, Huntington's disease, blood clots, depression, eye disease and arthritis.

Chris Zaslawski, of the College of Traditional Medicine at the University of Technology, Sydney, said the research was an important first step towards novel pharmaceuticals based on natural products. "But that doesn't mean (the compounds) will work in humans," he said.



Just some problems with the "Obesity" war:

1). It tries to impose behavior change on everybody -- when most of those targeted are not obese and hence have no reason to change their behaviour. It is a form of punishing the innocent and the guilty alike. (It is also typical of Leftist thinking: Scorning the individual and capable of dealing with large groups only).

2). The longevity research all leads to the conclusion that it is people of MIDDLING weight who live longest -- not slim people. So the "epidemic" of obesity is in fact largely an "epidemic" of living longer.

3). It is total calorie intake that makes you fat -- not where you get your calories. Policies that attack only the source of the calories (e.g. "junk food") without addressing total calorie intake are hence pissing into the wind. People involuntarily deprived of their preferred calorie intake from one source are highly likely to seek and find their calories elsewhere.

4). So-called junk food is perfectly nutritious. A big Mac meal comprises meat, bread, salad and potatoes -- which is a mainstream Western diet. If that is bad then we are all in big trouble.

5). Food warriors demonize salt and fat. But we need a daily salt intake to counter salt-loss through perspiration and the research shows that people on salt-restricted diets die SOONER. And Eskimos eat huge amounts of fat with no apparent ill-effects. And the average home-cooked roast dinner has LOTS of fat. Will we ban roast dinners?

6). The foods restricted are often no more calorific than those permitted -- such as milk and fruit-juice drinks.

7). Tendency to weight is mostly genetic and is therefore not readily susceptible to voluntary behaviour change.

8). And when are we going to ban cheese? Cheese is a concentrated calorie bomb and has lots of that wicked animal fat in it too. Wouldn't we all be better off without it? And what about butter and margarine? They are just about pure fat. Surely they should be treated as contraband in kids' lunchboxes! [/sarcasm].

Trans fats:

For one summary of the weak science behind the "trans-fat" hysteria, see here. Trans fats have only a temporary effect on blood chemistry and the evidence of lasting harm from them is dubious. By taking extreme groups in trans fats intake, some weak association with coronary heart disease has at times been shown in some sub-populations but extreme group studies are inherently at risk of confounding with other factors and are intrinsically of little interest to the average person.

The use of extreme quintiles (fifths) to examine effects is in fact so common as to be almost universal but suggests to the experienced observer that the differences between the mean scores of the experimental and control groups were not statistically significant -- thus making the article concerned little more than an exercise in deception


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