Aspartame and Cancer in Rats vs. Humans

A friend of mine (who I swear sometimes suffers from hyperactive agency detection device) referred me here when he was telling me that aspartame (sometimes abbreviated as APM) is hazardous to human health.  Specifically, he was talking about this:

An animal study that fed 0, 4, 20, 100, 500, 2500, and 5000 mg per kilogram of body weight of aspartame to rats saw lymphoma/leukemia increase in female rats, starting from about twice the risk with 20 mg per kilogram of body weight (a person weighing 75 kilograms or 165 lbs, consuming 1500 mg aspartame, or about 8 cans of diet soda) compared with a control group that was not fed aspartame.

It's strange that he pointed me there when the rest of the article talks about how the most recent HUMAN study shows no association between aspartame consumption and cancer rates, but nevertheless, I'd like to deal with this issue.

Before I get into that, let me give a brief overview of the idea behind non-nutritive or "0 Calorie" sweeteners.  Sugar (such as sucrose or fructose -- there are many types of sugars) is perceived as sweet because it interacts with taste buds on our tongue.  These taste buds have receptors that temporarily interact with sucrose and other sugars, and when that happens our brain gets a signal that says "oooh, this tastes sweet."  Each of these sugars has a varying level of "sweetness" as perceived by the brain depending on how it interacts with these receptors.  Evolutionarily, this is an advantage in that sugars are used by our bodies for energy, so being able to detect sugar and have a pleasurable response to it makes sense.  But when we consume more Calories than we require and we become obese, this reward response can become counterproductive.  One weapon against this is to use compounds that activate our taste buds for "sweet" but without that compound being used for energy.  Instead, the compound passes through your digestive tract without being absorbed.  That way the food tastes good without making us fatter!

Dr. Paul Offit on NPR's Talk of the Nation

Dr. Paul Offit was a guest on Talk of the Nation last week to talk about vaccines.  He talked about his new book, Deadly Choices, which discusses the anti-vaccine movement.  I've already ordered it on my Kindle, but I haven't read it yet.  I'm hoping I can use it as a break from GRRM's A Song of Ice and Fire series soon (I'm ~65% through the 3rd book, A Storm of Swords). 

I had a chance to listen to the podcast while I was at the gym today, and it was enjoyable but immensely frustrating.  I think what people forget is that sometimes medicine doesn't make logical sense until you spend years studying the subject.  One of the callers refused to accept Offit's argument that having 5 vaccines in a single doctor's visit still isn't even a blip in the radar compared to what your immune system (or a child's) encounters every day.  When you see a child scream while getting stuck with a needle a few times, I can understand how it would seem that it's a bigger deal to your immune system, but factually it simply is not.

I could spend hours talking about vaccines and the anti-vaccine movement, but instead I'll have you check out the podcast yourself.  It's ~18 minutes long so you can listen to it while you're driving to class/work or while you're at the gym.  If you have a podcast application on your phone, you can subscribe to Talk of the Nation as well, which makes finding and listening to stuff like this much easier.  Hopefully I'll find some time to read Deadly Choices soon.  Based on what I heard on the podcast, I'm sure it'll be worth the time!

The [boring] truth about rBGH and milk safety

A while back, I posted about some concerns brought to my attention by my sister-in-law, several of which dealt with cows and dairy products.  In particular, she had asked about:

1. rBGH/bST (recombinant bovine growth hormone, or bovine somatotropin):  They give this to cows to increase their growth and milk production.  What if it's still in the products we consume?
2. IGF-1 (insulin-like growth factor 1):  There are questions about IGF-1 being responsible for some cancers, and rBGH is supposed to elevate IGF-1.  Can it cause cancer in humans who drink milk from these cows?
3. Can antibiotics given to cows show up in our food supply, and are they increased or more harmful due to the hormones we give the cows?

I did a lot of searches on PubMed trying to find information about rBGH, and most of what I found dealt with animal trials or the public's perceptions of rBGH.  After all, if you've read some of the pro-organic websites out there, you might have seen something about the dangers of these chemicals, or even that the FDA has never studied the effects of these chemicals in milk consumed by humans.  Well, it turns out there's a very good reason why you don't find these studies anywhere -- it's because they're not necessary.  Medically.  Scientifically.  At all.

Why? Because well... Science.  It works, bitches!

College upperclassman fail at scientific reasoning

Ars Technica has a nice article on how many college upperclassman in science majors still suck when it comes to scientific and/or formal reasoning.  When we're children, we come up with simplified explanations for observed events that fit our experiences and/or expectations, but those explanations are often incorrect.  But hey, nothing against our 5-year-old selves, what else can you expect without a more formal science education!  The hope is that we'd shrug off these inaccurate, inadequate explanations as we progress through our science education.  Unfortunately, that's not happening nearly as often as we'd like.

I'll let you read the article on Ars for some of the details, but one thing in particular caught my eye (emphasis mine):

What's the root of this problem? The authors ascribe a lot of it to language. It's quite common to hear people describe fat as just melting away or vanishing, which doesn't encourage anyone to try to balance the books on where all those atoms actually go to, much less get them thinking in terms of their release as carbon dioxide and water vapor. The same problem persists in the language commonly used by biologists. We frequently refer to energy as "lost" when it's no longer available to an organism, but that doesn't mean it's not still there, typically in the form of heat.

Very similar to what I discussed about Cryolipolysis, right?  I've heard cryolipolysis's effects described as "melting away" the fat, but melting it away in one area doesn't do anything if it only comes back to the same area or somewhere else to take up residence again!  Some scientific reasoning is all that is needed to know that cryolipolysis can't deliver on all of the promises described by some of its proponents.  Better scientific reasoning skills could save people a lot of money and disappointment on procedures like that!

Cryolipolysis: What is it and does it work?

In the last couple weeks, I've realized that if I still lived back home, I'd probably be blogging a lot more often.  Talking to my family always gives me great ideas for new topics to cover on here!

This time, we have cryolipolysis (I think I've heard it called "cold lipo" as well).  This procedure involves exposing fat "problem areas" (like love handles) to intense cold.  It's non-invasive, and may seem like a nice alternative to people who are put off by the somewhat disturbing, violent procedure that is liposuction.  For people who are in good shape but still have some remaining problem areas they'd like to get rid of, it can be tempting.

The low temperature forces your adipocytes (fat cells) to undergo apoptosis (programmed cell death).  The idea is that killing these adipocytes will get rid of the fat they contain and thus reduce the amount of fat in the area.  A study from July 2009, entitled Clinical efficacy of noninvasive cryolipolysis and its effects on peripheral nerves looked at the procedure.  A search in PubMed for cryolipolysis didn't bring up any more recent studies for its efficacy in humans, which leads me to believe that this may have been something of a dead end (1.5 years and no larger trials to test the procedure?), but it's worth looking into. 

Before getting into the results of the study itself, let's consider what happens after an adipocyte undergoes apoptosis.  When an adipocyte dies, it releases its contents (fat) into the surrounding tissue.  From there, the fat can be taken up by the surrounding surviving adipocytes or picked up by the lymphatics and returned to the blood. From here, the fat has a few options:

1. Stay in the blood.  This would be bad.  What use is reducing your love handles if you give yourself high cholesterol instead?
2. Be "burned" for energy/calories.
3. Be transported throughout the body for storage, including back to the original site.
4. Excreted from the body.

Now it can get a little more complicated than that considering what else needs to happen to the released fat (lipids) before they can be stored or used for energy, etc., but that's enough for a general idea of what's going on.

Organic Manifesto

[Update:  I've done some research on rBGH and some of the concerns about hormone/antibiotics exposure in dairy products in a more recent post.  Refer to that if you're looking for more information about some of the topics mentioned here.]

No, I haven't "gone organic."  Over the holidays, I found out that my sister-in-law had read Organic Manifesto by Maria Rodale, and now she's been buying organic milk and other food products (peanut butter, fruits and vegetables, etc.).  She's an intelligent person, but she doesn't have a science or medical background.  She works as an accountant, but I'm not sure how well she knows statistics.  This can make it difficult to find, sort through, and understand the wealth of research on a topic such as organic food.

I thought it might be helpful to try to understand what specifically led her to make the switch. A lot of this is familiar to what I've read and heard elsewhere, but I'll list some of her main reasons here anyway:

• Preservatives.  She doesn't like all the preservatives in many foods today.  I told her that while we do use a lot of preservatives, many organic foods use them too (they're just "organic preservatives" that have a chemical formula observed in nature).  I also reminded her that preservatives are somewhat necessary if we want to avoid food-borne illnesses and live in societies like we do (food shipped across the country, available year-round, not have to grow your own food, etc.).
• Pesticides.  She doesn't like the idea of pesticides being used on her produce.  I told her that organic produce are grown using pesticides too, but that they are "organic" pesticides.  These are newer pesticides, and thus have a smaller body of evidence in support of their safety and efficacy.  Also, just because you ingest trace amounts of any pesticide does not mean you'll actually experience any health consequences from it.  Lastly, the best thing she can do is to wash her produce before she cooks/eats it if she wants to reduce pesticide exposure/ingestion.
• Antibiotics and hormones.  Cows are "pumped full" of antibiotics and hormones, and she doesn't want milk from these cows.  I told her I'd seen some research showing reduced rates of eczema in infants from pregnant mothers who consumed organic dairy products, but that I wasn't sure how large that decrease actually was -- i.e. if it's a 50% reduction, but only from .02% of infants to .01% of infants, it's really not that huge of an effect.
• Nutrition.  She didn't list this as a specific reason, but I reminded her that nutritionally speaking, organic and conventional foods are essentially identical.  One isn't healthier or richer in vitamins/antioxidants/joojoo than the other.
• "The Dirty Dozen."  These are 12 fruits and vegetables that supposedly have the highest rates of contamination by pesticides.  She said she specifically tries to buy these as organic products.

Overall, I got the sense that most of her complaints had come from this book and what others (I remember her mentioning Jillian Michaels specifically) had said about eating a healthier, more natural diet.  Let me be clear, there is a lot to be said about the benefits of eating a healthy diet that includes more fruits and vegetables than most Americans eat.  But "organic" does not mean "healthier" and "synthetic chemicals" do not automatically equal "toxic."  I wouldn't rely on Jillian Michaels to give me advice on medical science, and I wouldn't trust an organic farmer or salesperson to tell me why organic food is the greatest thing since sliced [organic] bread.  In the same way, don't come looking to me for advice on sculpting, playing in the NBA, or starting a KISS tribute band.

To Start a New Student Interest Group?

I'm debating starting a new Student Interest Group (SIG) at my med school.  We have all kinds of them for various specialties (dermatology, orthopedic surgery, family medicine, etc.), cultures/beliefs (LGBT, Christian Medical Association, Spanish language), and other commonalities.  I tried to get involved with one SIG last year that presents 1 hr presentations about science/medicine to students at a local junior high school to get them interested in the topic, but unfortunately the date I was scheduled to present was rescheduled.  But aside from that particular SIG, I haven't found one that really speaks to my interests.  I don't just want to be in some SIG that will sound good on a residency application; rather, I'd like to be a part of something that will have a lasting effect on myself and my peers by preparing us to deal with the challenges that lie ahead.

This led me to an idea for a new SIG, which I would call SkepSIG.  Catchy, I know.  It would basically be a way for medical students to get together to discuss science and medicine and how to effectively communicate these topics to patients.  When I read about how people respond when the scientific evidence contradicts their own beliefs, or when I observe such political and public outcry when it is recommended that an ineffective breast cancer drug have its FDA approval revoked, I can't help but consider how the scientific attitudes of physicians, patients, public officials, and the general public will affect my ability to help my patients in the future.

The "hCG Diet"

This is something I've been meaning to post about for some time now, but just haven't gotten around to it.  A while back, my mom told me about this diet someone in my family had started on.  She referred me to this website and asked what I thought about it.

I'm now 25% doctor after completing my 1st year of medical school, so hCG (human chorionic gonadotropin) is something I've actually learned a bit about in class.  hCG is what some people think of as the "pregnancy hormone."  It's a hormone that doesn't show up in a woman's body until she becomes pregnant (it's what at-home pregnancy tests detect) at which point it acts to maintain other hormone levels at high enough levels for the developing fetus.  hCG is also responsible for morning sickness, which disappears by the end of the first trimester because at that point the placenta can maintain hormone levels for the fetus all on its own.  Such a wonderfully useful structure, that placenta!

So, when I first read about this, I thought, "So he's basically just giving himself morning sickness.  I should tell him to take a pregnancy test too just to freak him out!"  The website itself is downright awful too, even going so far as to say that their "product is a professional grade homeopathic hCG weight loss product that is made in the USA."  A professional grade homeopathic product... so does that mean they use filtered water or spring water instead of just plain old water?  And it's made in the USA, so it has to be good, right?

Science Reporting

Pretty much the only evening news show I watch is NBC Nightly News with Brian Williams.  It's usually pretty good reporting, and I'm a big fan of Brian Williams.  I've always enjoyed his appearances on late night talk shows -- I sometimes wish he'd ditch that whole serious reporting thing and do his own late show!

Anywho, tonight's show had a segment about the environmental effects of the recent volcanic eruption(s) in Iceland.  It was doing well until Anne Thompson, the "NBC News Chief Environmental Affairs Correspondent", threw out this particular gem:

But [Sulfur Dioxide]'s reflective properties can also cause global cooling, leading some to wonder if this isn't the silver lining in the volcanic cloud.  Could it actually help reverse global warming fueled by man-made carbon dioxide, CO2?

You're right, a single volcanic eruption is going to spew enough sulfur dioxide into the air to reverse global warming.  Before I could even start to laugh at this idea, immediately after she stated this, it cuts to Richard Wunderman of the Smithsonian National Museum of Natural History, who says:

And it's pretty hard to reverse that [global warming] without reducing the greenhouse gases like CO2.

Why would she even pose the question like that if the next person is going to refute it?  To me, it seems like she's leaving the possibility open and acting as though this one particular expert says no, but people are still wondering if this is our cure-all for global warming!  With a subject like global warming, it seems to me that she shouldn't have left the idea lingering such that people might start thinking that these volcanoes are going to solve climate change.  It would have been much better to tack on something like "but climatologists say that these small effects are not significant enough to impact global climate change" before cutting to Wunderman's clip.

Maybe I'm overreacting, but I strongly believe that the media as a whole does a piss poor job when it comes to science reporting.  It's always about painting this picture of a big controversy that doesn't actually exist (e.g. the false notion that vaccines cause autism).  It's incredibly frustrating to watch. 

But you be the judge and check out the clip:

Visit msnbc.com for breaking news, world news, and news about the economy

Science-Based Medicine

I added another link to my sidebar at the right: Science-Based Medicine.  This one is similar in its overall theme and content to NeuroLogica, and Steven Novella posts on SBM as well.

A highly recommended you check out this post about Dr. Werner's explanation of homeopathy.  It's several months old now, but it's definitely worth reading.  As for Dr. Werner's video itself... it's certainly a must-see video, but for very, very different reasons.  Enjoy!

Skeptics' Guide to the Universe (SGU)

I'm not really sure how I've been missing out on this podcast for so long, but I've recently started listening to The Skeptic's Guide to the Universe (or just subscribe directly to the RSS feed here).  It's a little long, usually weighing in around 80 minutes or so, but it's worth it.  It's published once a week, and I've been listening to it while I've been at the gym all week.

SGU is produced by Dr. Steven Novella of NeuroLogica Blog, among others.  It's a refreshing "escape to reality" for those who struggle throughout the week listening to people who just don't seem to have a grasp on science and reality.  And unfortunately, many of those people have their own news programs.  Anyhow, check the SGU podcast out.  It's both informative and humorous, and the 80 minutes goes by pretty quick.  That's an added bonus if you're listening to it while driving or exercising, because it makes that activity go by fast too!

Sugar: The Bitter Truth

Everyone needs to watch this.  It's long, yes, but please check it out.  In medical school, I've heard all about the rise of obesity in the U.S., but this video really takes an in-depth look at how we got to this point.