Tuesday, September 29, 2015

What is the "Ideal" Systolic Blood Pressure?

Current guidelines for treating high blood pressure are that anyone with systolic blood pressures of 140 mmHg or above (or diastolic pressures above 90mmHg) should be treated to lower their blood pressures below those numbers. But the guidelines beg the question; is there an ideal systolic pressure that is even lower than 140?

According to a recent article in the New York Times, a major new research study shows that lowering systolic pressure to 120 or below reduces the risk of heart attacks, heart failure and strokes by a quarter and reduces the risk of death by a third, compared to just lowering systolic pressure to 140 or below. The findings imply that treatment of high blood pressure should be much more aggressive than the current guidelines suggest.

However, a closer reading of the actual study design reveals an important point: the study examined only patients who are already at risk for heart disease. These were not normal healthy people who just happened to have systolic pressures of 130 mmHg; they were all subjects with systolic blood pressures above 130 mmHg who also had evidence of cardiovascular disease, chronic kidney disease, cardiovascular disease risk factors, or were older than 75.

The results are clear; patients at high risk of cardiovascular disease should be treated more aggressively than in the past, with a goal of lowering their systolic pressures to 120 mmHg or less. But what about normal people who just happen to have a systolic pressure of greater than 120 mmHg? Cardiologists may begin recommending that they be treated, too (to the delight of the companies selling antihypertensive drugs.) But I'm not so sure. All drugs have side effects: when drugs are recommended, the potential benefits should outweigh the risks. And we just don't know whether lowering systolic blood pressure to below 120 in otherwise healthy people is a good idea.

Monday, September 28, 2015

Forest Fires and Global Warming

The recent spate of forest fires in the Western United States raises an interesting question; to what extent are the recent increases in Western forest fires linked to global warming? And more importantly, to what extent could the fires themselves contribute to global warming?

According to a recent article in The Economist, the National Research Council estimates that for every degree of global warming, the amount of Western land burned in North America each year could quadruple. With an estimated 2-degree increase global temperatures expected by the end of this century, that would be a 16-fold increase in land burned by forest fires by 2100. Sixteen-fold!

But this is where it gets really interesting. Trees absorb CO2 from the atmosphere as they grow, and they release that CO2 into the atmosphere when they are burned. So not only do forest fires add CO2 to the atmosphere, exacerbating the global warming trend; they also reduce the number of trees available to absorb CO2.

It's not going to be pretty for our descendants if we can't get global warming under control soon.

Saturday, September 19, 2015

Are Antimicrobial Soaps Effective?

Do antibacterial soaps protect you against dangerous bacteria? The answer is probably not.

In a study published in the Journal of Antimicrobial Chemotherapy, researchers examined the effectiveness antimicrobial liquid soaps containing triclosan, the most common ingredient in these soaps. First, they exposed 20 different strains of harmful bacteria to the soaps in petri dishes. The antimicrobial soaps did kill the bacteria, but only after 9 hours or more of exposure. Then, to test the effectiveness of the antimicrobial soaps under more real-world conditions, they spread bacteria on the hands of volunteers and asked them to wash their hands in cold water for 30 seconds with either antimicrobial or normal (non-antibacterial) soaps. Under these conditions, there was no difference between the antimicrobial soaps and the normal soaps in terms of their ability to kill the bacteria.

The bottom line is that antimicrobial soaps containing triclosan do have antimicrobial properties under certain conditions (9 hours!), but they are not effective under ordinary hand-washing conditions. It's something to think about, especially since any exposure to antimicrobial agents is likely to increase antibiotic resistance to that antimicrobial agent in the long run.

On a totally unrelated subject, it's a pet peeve of mine that the original article in the Journal of Antimicrobial Therapy is not available to the public for free; you can only see the abstract. If it's important information that was funded by public funds, it should be available to the public. In this particular case you can get more information from the popular press than from the journal itself. And that's a shame.

Thursday, September 17, 2015

California Legislature Passes a Death With Dignity Bill

The California legislature passed a bill last week that would allow physicians to prescribe a life-terminating drug for terminally ill patients under certain circumstances. Called the End Of Life Option Act, the bill would require that a person be evaluated by at least two physicians, both of whom would have to declare that the person has less than six months to live. In addition, the patient would have to submit a written request and make two oral requests at least 15 days apart to be eligible for the drug.

The bill was inspired by the plight of Brittany Maynard, a California resident who was diagnosed in January of 2014 with a deadly brain tumor. Surgery to remove it failed, and she was given six months to live. At the time, only three states (Washington, Oregon, and Vermont) had laws that allowed physicians to prescribe life-ending drugs to such patients; two other states (Montana and New Mexico) allow it based on previous cases. So Ms. Maynard moved to Oregon where, when she judged the time was right, she died on November 1, 2014. Before her death Brittany campaigned for Death With Dignity laws, including in her original home state of California. The campaign is still ongoing after death (visit her website, thebrittanyfund.org). At least 15 states are now considering such laws.

Death with dignity laws are not for everyone. They are specifically designed to allow terminally ill patients some control over the process of their own death. They are NOT for just any old person who says they are done with life. Interestingly, even among terminally ill patients who are prescribed life-ending drugs, only about half ever actually use them. Simply having the choice seems to bring a measure of peace to some patients.

California Governor Jerry Brown has not said whether or not he will sign the bill, the final step in making it law.

Friday, September 4, 2015

A Different Kind of GMO

Here's an idea; instead of genetically modifying food plants so that they're resistant to insects, why not genetically modify the insect pests so that they can't reproduce? Perhaps that would be more palatable to people who are concerned about eating GMOs.

You've probably never even heard of a diamondback moth, and why should you have?  It's an unloved pest of cabbage patches; an invasive species that is hard to kill.  Back in the 1940s it became the first insect pest to develop resistance to DDT, a pesticide now banned.  It even resisted a technique that works with some insects - irradiation to sterilize male insects.  These days, cabbage, kale, and broccoli farmers have to spray multiple different pesticides in a single season just to keep it in check, at an annual cost of about 5 billion dollars.

But now a solution may be on the horizon: Researchers at Cornell University in upstate New York have developed a technique for genetically modifying diamondback moths so that the female larvae all die before reaching maturity.  The genetically modified moths have not yet been released into the field, and probably won't until at least 2016.  First the moths will be tested in enclosed outdoor cages to see how well they normal moths.  And of course there are regulatory hurdles to overcome.

Understandably, people who categorically oppose all GMOs oppose this one as well.  But this GMO does have some features that might make it more acceptable, according to a New York Times article. 1) It is not a human food.  2) It doesn't stray far from where it was born (or released).  3) Even if it did stray, it would be killed by the harsh New York winters, the same as adult normal moths.  4) It does not violate the rules of organic farming, so it wouldn't matter if it strayed into an organic farm field.  5) And finally, thanks to another genetic modification, the genetically modified moth glows red under ultraviolet light, making it easily identifiable from a normal moth.

It'll be interesting to see if this GMO is ever approved for use in open farm fields.   

Thursday, September 3, 2015

How Did the FDA Determine the "Daily Value" for Added Sugars?

Last month I posted a blog about the FDA's new proposed changes to food labels on processed foods (see this blog Aug. 2, 2015). One of the most controversial changes was the one that defined for the first time what should be the maximum daily consumption of "added sugar" per day. Those are the so-called empty calories of sugars that food producers add to processed foods and soft drinks solely to get you to buy more of them. The FDA says that the maximum daily consumption of added sugars, which they call the "daily value" (DV), should be no more than 200 calories (50 grams) per day - the amount in just a single 16-oz soda.

Since then several people have asked me: How did the FDA come up with that number? The answer is that the FDA is relying on the Scientific Report of the 2015 Dietary Guidelines Advisory Committee, a governmental panel of scientists charged with reviewing the available scientific research and making recommendations regarding a healthy diet. The Committee found that high intakes of added sugars are associated with increased risks of heart disease, obesity, and type 2 diabetes, and concluded that "strong evidence supports reducing added sugars intake to reduce health risks."

The FDA says that according to the available scientific evidence, "it is difficult to meet nutrient needs while staying within caloric requirements if one exceeds 10% of total calories from added sugar." The FDA already uses a figure of 2,000 calories per day as the standard daily caloric intake; multiplying by 10% yields a figure of no more than 200 calories should come from added sugar.

By the way, the FDA says that the government "has no specific recommendation for added sugars"; that it is only providing the information to help consumers make informed choices. Really? A maximum daily value of no more than 200 calories doesn't sound like a "recommendation" to you?