Thursday, April 19, 2007

You knew bacon was bad for you, didn't you?

Anything popular will be targeted by the attention-seekers. Nitrites used as preservatives are once again in the crosshairs. The fact that nitrites are found naturally in many "correct" foods (such as broccoli and spinach) seems to have been overlooked. The journal abstract is here. Once again the conclusions appear to rely on comparisons between extreme groups -- which is inherently uninformative about the population at large, suggests weak effects and is very prone to confounding from other influences. For an earlier comment on this perennial scare see here

People who frequently eat cured meats such as ham, hot dogs and bacon face a higher risk of lung disease, researchers said today, citing additives called nitrites as a possible cause. Those who ate cured meat products at least 14 times a month were 78 per cent more likely to develop chronic obstructive pulmonary disease than people who did not eat these meats, even after the researchers sought to account for many other risk factors including smoking, overall diet and age. Chronic obstructive pulmonary disease, also called COPD, refers to emphysema and chronic bronchitis, which interfere with normal breathing.

This amount of consumption also was associated with poorer overall lung function, according to a study involving data on 7352 Americans age 45 or older. The average age of the people studied was 64.5 years.

The American Meat Institute, an industry trade group, said the findings were based on outdated assumptions about nitrite levels in cured meats. "This article in no way changes a basic fact - and that is that cured meats are among the safest meat products on the market," said institute spokeswoman Janet Riley. "The very premise of this study - that cured meats are high in nitrite - is patently false," Ms Riley added, saying less than 5 per cent of human nitrite intake comes from cured meats and their nitrite levels have declined greatly in recent decades.

The research was led by Dr Rui Jiang of Columbia University Medical Centre in New York and was published in the American Journal of Respiratory and Critical Care Medicine. Dr Jiang said nitrites - added to cured meats to prevent spoilage and provide colour - may cause damage to lung tissue resembling emphysema, but added the study's design did not allow her to state definitively that the nitrites caused lung disease. More research is needed before that claim can be made, Dr Jiang said.

She could not rule out, for example, that people who eat a lot of cured meats - hot dogs, cold cuts, sausage, bacon, cured hams and the like - may be more likely to have an unhealthy diet and lifestyle that might account for the higher lung disease risk. The people in the study who ate the most cured meats were more likely to be lower-income men and smokers and were more likely to have diets lacking in fruits, vegetables and a number of vitamins.

Cigarette smoking is the leading cause of COPD. Previous research linking nitrites in cured meats to certain cancers has proven controversial, with many scientists faulting the methodology and conclusions in these studies.


And I suppose it is altogether too wicked of me to mention this:

"Could the salt that preserves hot dogs also preserve your health? Scientists at the National Institutes of Health think so. They've begun infusing sodium nitrite into volunteers in hopes that it could prove a cheap but potent treatment for sickle cell anemia, heart attacks, brain aneurysms, even an illness that suffocates babies."

Killers lurk in spa bath

THERE could be a killer lurking in your spa, and the best way of slaying it and its lethal compadres is simple, effective and very cheap. It's elbow grease.

This week Queensland Health sent out a notification that two visitors to a Gold Coast resort had been diagnosed with legionnaires disease - which they had contracted after using the resort's spa bath.

It makes sense that the warm, moist environment inside the filters and pipes of spa baths and pools would make the perfect place for bugs such as legionnaires pneumophilia to set up home and procreate. Australian Medical Association Queensland infectious diseases expert Michael Whitby said the legionella bug was readily found throughout the world, from Antarctica to jet engine oil, but it was most commonly found in water. He said the major outbreaks in Australia, which include a scare at the Yamanto police station in Ipswich in 2005, had been associated with the cooling towers of large buildings that had not been properly maintained. "They have a lot of metal fragments that help legionella to grow, and for legionella to get into your lungs it has to be in very small particle size so you have to actually spray them out of the airconditioning system to breathe them in," Dr Whitby said.

It's this spray, created when water is expelled at high pressure, that can make spas a risk. Queensland Health senior director of population health Linda Selvey said the mist provided a perfect avenue for bugs to make their way into lungs. "The big issue with spas is that the water is warmer so it provides a nice environment for bugs to live in," Dr Selvey said. "Secondly, because you're forcing air through the pipes at reasonably high pressures to get bubbles, you get a mist of water above the spa pool and you actually acquire legionella infection by breathing in the bugs."

Dr Selvey said the best way to prevent infection was to empty spa pools once a month and manually clean the filters and pipes. "With spa pool maintenance it's very important to empty the pool and pull out the filters and with a bit of elbow grease scrub them clean," she said. "And the emptying and cleaning of filters needs to be done once a month."

There are several types of legionella, but the two that occur most commonly here are pneumophilia and longbeachae. Pneumophilia is the type associated with spas and cooling towers, as it produces pneumonia-like symptoms such as a high temperature, coughing and shortness of breath. Longbeachae is found in soil and is the reason behind many potting mixes carrying safety warnings. Both are potential killers.

This year there have been 12 cases of legionnaires disease in Queensland. Legionella is a relatively modern bug, identified in the late 1970s after several delegates from an American Legion conference in Boston fell ill and died shortly after the meeting. While a good scrub is the best way of keeping pipes and filters clean, washing spas out with degreasing solutions is also important to control buildups of body fats, soap residue, oils and scum



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.