Saturday, February 07, 2009

Joint Effects of Sodium and Potassium Intake on Subsequent Cardiovascular Disease

This is a rather strange set of findings. Basically they found that salt intake or potassium intake had no effect on heart disease (How awful for the anti-salt crusaders!) -- but then they tortured the data with all sorts of elaborate statistics until they found that something happened if you looked at salt intake and potassium intake together. The most reasonable conclusion: Eat what you like. If you are the worrying type, eat bananas occasionally. They have a fair bit of potassium in them. Potatoes do too

By Nancy R. Cook et al.

Background: Previous studies of dose-response effects of usual sodium and potassium intake on subsequent cardiovascular disease (CVD) have largely relied on suboptimal measures of intake.

Methods: Two trials of sodium reduction and other interventions collected 24-hour urinary excretions intermittently during 18 months from September 17, 1987, to January 12, 1990 (Trials of Hypertension Prevention [TOHP] I), and during 36 months from December 18, 1990, to April 7, 1995 (TOHP II), among adults with prehypertension aged 30 to 54 years. Among adults not assigned to an active sodium reduction intervention, we assessed the relationship of a mean of 3 to 7 twenty-four-hour urinary excretions of sodium and potassium and their ratio with subsequent CVD (stroke, myocardial infarction, coronary revascularization, or CVD mortality) through 10 to 15 years of posttrial follow-up.

Results: Among 2974 participants, follow-up information was obtained on 2275 participants (76.5%), with 193 CVD events. After adjustment for baseline variables and lifestyle changes, there was a nonsignificant trend in CVD risk across sex-specific quartiles of urinary sodium excretion (rate ratio [RR] from lowest to highest, 1.00, 0.99, 1.16, and 1.20; P = .38 for trend) and potassium excretion (RR, 1.00, 0.94, 0.91, and 0.64; P = .08 for trend) but a significant trend across quartiles of the sodium to potassium excretion ratio (RR, 1.00, 0.84, 1.18, and 1.50; P = .04 for trend). In models containing both measures simultaneously, linear effects were as follows: RR, 1.42; 95% confidence interval (CI), 0.99 to 2.04 per 100 mmol/24 h of urinary sodium excretion (P = .05); and 0.67; 0.41 to 1.10 per 50 mmol/24 h of urinary potassium excretion (P = .12). A model containing the sodium to potassium excretion ratio (RR, 1.24; 95% CI, 1.05-1.46; P = .01) had the lowest Bayes information criterion (best fit).

Conclusion A higher sodium to potassium excretion ratio is associated with increased risk of subsequent CVD, with an effect stronger than that of sodium or potassium alone.

Arch Intern Med. 2009;169(1):32-40. January 12, 2009

Researchers find way to cut ozone's effects on asthma

Researchers say they may have found a key to treating the ozone-triggered asthma attacks and respiratory problems that plague residents in hot-weather states like Arizona. A study released Tuesday by the National Institutes of Health shows for the first time how ozone irritates the lungs, findings that could ultimately lead to better treatment options for asthma sufferers. The report has particularly wide-reaching implications in this state, which not only has one of the nation's highest rates of asthma but struggles to control ozone pollution during the summer months.

I can't say we found the cause of asthma, but in this instance, we were able to completely get rid of the symptoms," said Stavros Garantziotis, principal investigator with the National Institute of Environmental Health Sciences, part of the NIH. "We were able to stop the irritation (in the lungs)." Any new drugs or therapies that arise from the research are still years away, he cautioned.

The study, done in conjunction with Duke University, found that mice exposed to so-called bad ozone, a key component of urban smog, produced high amounts of a sugar called hyaluronan. The sugar was directly responsible for the narrowing or constriction of the animals' airways, a primary cause of asthma symptoms and attacks in humans. "We found that it is not the ozone itself that causes the body to wheeze but the way the lungs respond to (it)," Garantziotis said.

Hyaluronan is found naturally in many tissues of the body, including skin and cartilage, and has been used to treat such conditions as osteoarthritis of the knee. But researchers found that the mice produced it in a different, more harmful form after being exposed to ozone. They also discovered they were able to neutralize this "bad" hyaluronan and stop the lungs' airways from narrowing by using several proteins and an altered form of the sugar.

As many as 548,000 state residents suffer from asthma, according to the American Lung Association of Arizona, and studies suggest that Valley's year-round pollution problems exacerbate those symptoms. Much of the local attention has focused on links between respiratory problems and particulate pollution, the tiny bits of dust and soot in the air. But ozone is a growing concern for state and local health officials.

In 2008, metro Phoenix exceeded the federal health standard for ozone on 28 days, compared with none in 2007 and nine in 2006. Part of the jump was due to a tightening of federal standards. Nationally, the Environmental Protection Agency estimates that ozone-related health problems cost the United States $5 billion a year in premature deaths, hospitalizations and school absences.


1 comment:

Anonymous said...

nice article upon pollution issue.....