Gut Bacteria May Contribute to Obesity

Why can some people lose weight easily, while others just seem to gain weight no matter what they do?   The standard explanation has been genetic differences in metabolism that affect how you store and use the energy in the food you eat.

But genetics doesn’t explain differences in weight between identical twins.  One hypothesis is that in identical twins, differences in the ability to gain or lose weight may be due to different populations of gut bacteria.  We know that the human body is home to trillions of bacteria, many of them in the gut.  Gut bacteria are involved in metabolizing what you eat, largely for their own purposes of course, but possibly also affecting your metabolism.

In a recent experiment designed to find out whether gut bacteria might be affecting metabolism enough to alter a person’s overall body weight, scientists transplanted gut bacteria from pairs of twins “discordant for obesity” (one heavy and one not) into germ-free mice.  They found that gut bacteria from the obese twin caused the mice to gain more weight than gut bacteria from the lean twin.

The obvious conclusion is that the type of bacteria that inhabit your gut might indeed have an effect on a your body weight.  The next step would be to find out which gut bacteria might cause people to gain too much weight or to stay lean, and then to culture the lean ones or learn how to inhibit the weight-gaining ones.  Perhaps someday, cultures of specific gut bacteria will become components of diet pills.   But don’t hold your breath - it could take decades to tease out which bacteria would work the best.

Call me crazy, but my guess is that some unscrupulous diet clinics may seize on this research and begin to promote an unproven "therapy" that involves transferring cultures of gut bacteria from lean people into obese ones, with the promise that it'll cure obesity.  I hope I'm wrong. 

Sloppy Science Reporting

It concerns me when reporters get sloppy when reporting science news, or try to make the news personal in order to attract readers (do they teach that in journalism school?).   Consider the article on The Weather Channel’s website entitled “Which state is the worst for your heart?”   The obvious implication is that some states are better than others for my heart.  I clicked on the article just in case there really were some states I should avoid (no, not really!)  I’m sorry to say I came away disappointed, and here’s why.

The article ranks the 50 states from best or worst in terms of deaths from heart disease, based on statistics from the U.S. Centers for Disease Control (the CDC).  The data are legitimate, but the the title of the article is misleading.  The number of deaths from heart disease in a particular state does not necessarily mean that I would have that same risk if I were to live there.   For the most part, my risk factors are my own, regardless of which state I reside in or am traveling through at the moment.  Statewide differences in deaths from heart disease are a complex mix of factors, including genetics of the state’s population, differences in local diets, job stresses, environmental pollutants, and other as yet unknown factors, spread out over an entire lifetime.  The differences between states are interesting in that they may help us identify these risk factors, but they have almost nothing to do with me personally.

The article also makes no distinction between the past and the future.  Take for example, the following statement about the best state, Minnesota; “In this state, 36.3 residents out of every 100,000 will die of a preventable heart condition this year, according to the most recent CDC data available.”  Wrong! First, a fraction of a person cannot die (Thirty six point three people will die?).  And second, the CDC is not in the habit of trying to predict future deaths; it simply reports deaths that have already happened.  A correct statement about Minnesota would have read, “In this state, between 2001 and 2010 an average of 36.3 residents out of every 100,000 died of a preventable heart condition each year, according to the most recent CDC data available.”  See the difference?

These may seem like minor errors, but if we’re going to report on science, why not try to get it right?  I, for one, will not worry if I ever move to Mississippi (the state with the most deaths from preventable heart disease, at 95 residents per 100,000).  My risk factors, whatever they are, are already pretty well set.

For more on this subject, go to a previous blog post titled "Journalistic Bias in Science Reporting."

A Carbon Tax to Curb Global Warming?

What’s the best way to reduce global emissions of greenhouse gases such as CO2? Appealing to people’s sense of social responsibility, such as asking them to buy cars with better gas mileage or turn down their thermostats, doesn’t seem to work terribly well. Most of us are more focused on how we’re going to pay the rent or buy that new car than on our personal contribution to global warming. Plus we have no idea how to calculate our carbon footprint, as its called. And targeted government action, such as requiring that cars achieve a certain mileage or demanding that we car-pool to work, are highly intrusive on our lives. Is there a better way?

One idea would be to put a price (okay, a tax) on greenhouse gas emissions, wherever and whenever they occur. That way, the cost of preventing global warming is uniformly distributed into everything we do that results in the increased release of greenhouse gases. We don’t even have to be aware of it. It just means that the prices of all goods and services that we use would go up by an amount that would reflect the actual cost of removing the amount of CO2 those goods or services produced. A carbon tax would mean that each of us would be paying for our carbon footprint, without having to go to extremes of a change in lifestyle. For more on why a carbon tax might be the best idea yet, see the essay by Harvard economist Gregory Mankiw.

Yes, it would be difficult to put the right price (or tax) on carbon emissions. Too much and it could stifle economic growth and prosperity. Too little, and we wouldn’t solve the global warming problem. That’s a topic for the future. Surely it could be done, if we put our minds to it.

Preventable Deaths from Dental Disease

People who don’t have dental insurance are more likely to delay going to the dentist than people who do have dental insurance.  As a result, early signs of tooth disease may go undetected in the uninsured.  Then when a medical or dental problem becomes major and the person is in enough pain, the uninsured tend to go to a medical emergency room rather than a dentist, where they can be assured of emergency care regardless of whether or not they can pay.

Perhaps as a result of this tendency to wait too long and then go to a medical emergency room, the number of hospitalizations from serious complications of dental infections, and even deaths from dental disease, are on the rise.   According to a recent study, between 2000 and 2008 more than 60,000 people were hospitalized for periapical abscesses, a condition that develops in untreated tooth decay in which the tip of the tooth’s root becomes seriously infected.  Sixty-six patients died from complications of the condition.  That’s unfortunate, because periapical abscesses are less likely to occur in persons receiving regular dental care.   In addition they can be treated effectively by root canal therapy or tooth extraction when diagnosed early enough.

Hospitals have no choice but to write off emergency room care given to patients who cannot pay.   What this means is that a lack of access to dental care (because of a lack of insurance or an inability to pay) may be driving up the cost of charity medical care instead.  And people are dying needlessly.  It’s worth thinking about when we discuss universal access to health care – what about dental care?

The NFL Settles Lawsuits with Former Football Players

We first mentioned the possibility that repetitive head trauma might cause a form of brain injury called chronic traumatic encephalitis (CTE) over a year ago (see this blog, May 17, 2012). Over a thousand lawsuits had already been filed against the National Football League by former football players, who claimed that their symptoms of brain injuries were caused by repetitive head trauma received during their playing years. At that time the NFL disavowed responsibility but agreed to look into it.

Well, the NFL did look into it, saw the handwriting on the wall, and did the right thing. This week the league settled all the lawsuits at once by agreeing to pay out $765 million over the next 20 years to diagnose and compensate former players who may have suffered brain injury during their playing years. The amounts each player receives will be determined by the player’s age, years of play, and medical condition, but ultimately there’s a cap on the payout to any individual player; $5 million for former players with Alzheimer’s disease, $3 million for dementia, and $4 million to the estate of players diagnosed after their deaths with CTE, which can only be diagnosed by examining the brain after death.

And what does the NFL gain, other than goodwill? The league does not have to reveal what it knew about a causal link between repetitive head trauma and CTE and when it knew it. In other words, it does not have to admit wrongdoing. Fair trade? You decide.

As a result of what we now know about repetitive brain injury and CTE, the NFL has instituted rule changes designed to prevent head injuries from occurring in the first place, and to prevent players who have been injured from returning to play until they have fully recovered. That means that it may be harder for current players who later develop CTE to recover damages.