Obesity and the Brain

Nature Genetics just published a paper that caught my interest (1). Investigators reviewed the studies that have attempted to determine associations between genetic variants and common obesity (as judged by body mass index or BMI). In other words, they looked for "genes" that are suspected to make people fat.

There are a number of gene variants that associate with an increased or decreased risk of obesity. These fall into two categories: rare single-gene mutations that cause dramatic obesity, and common variants that are estimated to have a very small impact on body fatness. The former category cannot account for common obesity because it is far too rare, and the latter probably cannot account for it either because it has too little impact*. Genetics can't explain the fact that there were half as many obese people in the US 40 years ago. Here's a wise quote from the obesity researcher Dr. David L. Katz, quoted from an interview about the study (2):

Let us by all means study our genes, and their associations with our various shapes and sizes... But let's not let it distract us from the fact that our genes have not changed to account for the modern advent of epidemic obesity -- our environments and lifestyles have.

Exactly. So I don't usually pay much attention to "obesity genes", although I do think genetics contributes to how a body reacts to an unnatural diet/lifestyle. However, the first part of his statement is important too. Studying these types of associations can give us insights into the biological mechanisms of obesity when we ask the question "what do these genes do?" The processes these genes participate in should be the same processes that are most important in regulating fat mass.

So, what do the genes do? Of those that have a known function, nearly all of them act in the brain, and most act in known body fat regulation circuits in the hypothalamus (a brain region). The brain is the master regulator of body fat mass. It's also the master regulator of nearly all large-scale homeostatic systems in the body, including the endocrine (hormone) system. Now you know why I study the neurobiology of obesity.


* The authors estimated that "together, the 32 confirmed BMI loci explained 1.45% of the inter-individual variation in BMI." In other words, even if you were unlucky enough to inherit the 'fat' version of all 32 genes, which is exceedingly unlikely, you would only have a slightly higher risk of obesity than the general population.

Hollywood's "Dilemma": Should "Gay" Jokes Be Censored?

Recently I went to see "The Social Network". We watched several movie trailer previews, including the Ron Howard directed film "The Dilemma". The preview included a scene with Vince Vaughn exclaiming to a conference room full of colleagues, "Ladies and gentlemen...electric cars are gay". He goes on to clarify that he does not say "gay" to mean happy, instead he compares its level of "coolness" to your parents chaperoning a school dance. I leaned over to my husband and whispered, "I thought they were taking this scene out of the trailer?". I guess it had not yet been pulled (and was instead being seen by millions, as The Social Network was #1 at the box office that week).

The controversy regarding this quote began several weeks ago. CNN's Anderson Cooper was one of the first to draw attention to the preview when he appeared on the Ellen DeGeneres Show. His argument (especially in light of the recently publicized suicides involving gay children/teenagers) was that we must "make those words unacceptable cause those words are hurting kids". In addition, the Gay & Lesbian Alliance Against Defamation (GLAAD) put out a statement on the situation:

"When 'gay' is used as a pejorative, it frequently sends a message- particularly to youth and their bullies- that being gay is wrong and something to laugh at. We invite Vince Vaughn to work with us and help insure that gay youth and those perceived to be gay aren't put in harm's way by such jokes".

Last week, Vince Vaughn addressed the above concerns with his own statement that highlighted his feelings that the "gay joke" should be kept in the trailer and in the movie:

"Let me add my voice of support to the people outraged by the bullying and persecution of people for their differences, whatever those differences may be. Comedy and joking about our differences breaks tension and brings us together. Drawing dividing lines over what we can and cannot joke about does exactly that; it divides us. Most importantly- where does it stop?"

ABC's The View also discussed this during its "Hot Topics" show yesterday. I was actually pretty surprised that there seemed to be consensus and support for Vince Vaughn's statement. How can you censor a "character"? This was not about Vince making homophobic statements...but it was the statements of his character. What if the character is a jerk? Then he/she will sound like a jerk. Whoopi Goldberg spoke about recently watching "Roots" on TV and how much of the message was lost due to the censoring of the racist language.

I can see both sides of the argument on this one. Of course, people of all ages look to celebrities and movies to be role models and to confirm (or break) social norms. Therefore, statements using "gay" as a pejorative can absolutely influence the beliefs of an audience. However, I also understand the slippery slope of censorship and the concern that stories can no longer be told with the same honesty and depth of characters. It is also unclear how this censorship would be overseen and enforced. Can we always tell the difference between a statement of someone's beliefs and their attempt at a joke? And just because something is intended as a joke, does that really mean there are no consequences? If your boss "jokes" about how your clothes fit...it is still sexual harassment.

With tomorrow being "Spirit Day" to combat anti-LGBT bullying, it seemed very timely to toss this "dilemma" out to my readers for comment. I look forward to your thoughts.

Courteney and David: A Poorly Designed PSA That Makes Me Want to "Scream"

So Courteney Cox and David Arquette are having a tough week. First they announced their separation and now I have to highlight the poor design of a recent public service announcement (PSA) in which they starred. I must say- they made a much better team on the set of their "Scream" movies.

A recent Newsweek article entitled "Can PSAs End Domestic Violence?" discussed the Cox/Arquette PSA and outlined the challenges of using this particular health communication channel to address the public health problem of domestic violence. The article quotes a wonderful professor of mine (thank you Dr. Emily Rothman for posting this link), so I decided to check the PSA out for myself. Overall, my impression was not good. Let's compare the PSA to some best practices and/or guidelines and see how it holds up. A great resource on this (and all aspects of program planning) comes from the Community Toolbox:

1. PSA Length
A typical PSA runs about 30 seconds. This video runs 1 minute, 50 seconds. And the viewer does not even know what the video is about (cue a random segment about "furry" sex) until the timer hits 1 minute, 25 seconds. They could have very easily lost viewers by that point (either due to boredom, confusion, or because they were offended by the "furry" segment).

2. PSAs Should Have a Clear Message and Call To Action (i.e., what do you want the viewer to do after they see your video?)
So I was a little surprised that the video did not include any specific hotline numbers. In case the audience included victims of DV, you would think that it would be a priority to list those resources. Instead, the only "action" that I could see outlined was how to donate to "OPCC"...and it was unclear what that organization was. So I followed the instructions at the end of the video that gave their Facebook address. Again, there is a huge logo that says "OPCC" (still not sure what that is, so I probably won't give money) and finally (in much smaller writing) some hotline numbers on the left. I went one more step and went to the Ocean Park Community Center (OPCC) website, where it still wasn't immediately clear how this organization supported domestic violence prevention. Apparently, this PSA was to support one of the community programs called Sojourn (a women's shelter)...but geez- how hard was that to figure out!!!???

3. Like any good health communication product, there should be a clear target audience
I have no idea who the audience was for this PSA. This is a direct result of the lack of a clear "call to action". This video had no idea who they expected as an audience or what they wanted those individuals to do. Before the video starts, we are told "this is not for kids" (again- due to the "furry"). So kids are excluded as a possible audience- which is a shame because young adults are also victims of domestic violence. I'm assuming that domestic violence victims themselves are not the audience, since the video did not include any links to DV hotlines/shelters. I doubt the audience was supposed to be DV perpetrators, because I doubt that they would be giving donations. So maybe the intended audience was just potential donors? It is unclear.

4. Evaluation
Ahh! I know I'm a broken record about this issue on my blog. As Dr. Rothman states in the Newsweek article, "there haven't been that many well-designed, rigorous evaluations of the ad's effectiveness". The OPCC spokesperson says that it has been effective because "people are talking about the ad" (how do we know?) and Facebook traffic was up (as of tonight, just 365 people had "liked" the page). But even if "talk" is increased, is that really changing the attitudes or behaviors that were (maybe) targeted by this PSA? If they had clearer goals and a call to action (e.g., The audience for this PSA is women who are victims of DV and the behavior we want to see is an increase in calls to our hotline)- it would be much easier to evaluate. And that evaluation would go well beyond "awareness".

Vacation

I'll be out of town until the beginning of November, so I won't be responding to comments or e-mails for a while. I'm going to set up a post or two to publish while I'm gone.

As an administrative note, I get a number of e-mails from blog readers each day. I apologize that I can't respond to all of them, as it would require more time than I currently have to spare. The more concise your message, the more likely I'll read it and respond. Thanks for your understanding.

Giuliana and Bill: A Reality Show Addressing the Real Stigma of Infertility

Talking about infertility makes people uncomfortable. Those struggling are uncomfortable because it is extremely personal. Perhaps they feel like they've failed at something that should come naturally...something that seems easy for everyone else. Perhaps it is difficult to explain why they cannot bring themselves to go to a friend's baby shower. Perhaps people at work ask them "when are you going to have a baby?"...not realizing that it is an incredibly painful question because they have been trying for years.

With this as the current state of affairs, you can imagine my surprise to see Giuliana and Bill Rancic come on The View two weeks ago and tell their story about trying In Vitro fertilization (IVF) and suffering a miscarriage. Their ordeal is also documented on their reality show: Giuliana & Bill. I just finished watching my DVR copy of their season premiere which follows them on their IVF cycle. What I really appreciated was the honest display of how difficult the cycle was. Were they both on board with this next step? How scary were the bags and bags of medication!? How would they coordinate their work schedules to make it happen? How could they keep it a secret from their work colleagues and their families? Who would stay home with Giuliana for her 48 hour bed rest? And of course it was difficult to watch them get the happy news of "you're pregnant!" at the end of the episode, since we already knew what was to come nine weeks later.

But what I really want to talk about are the huge strides they've made in reducing the stigma of IVF and miscarriage in just a few short weeks since they've come forward. I've spoken in previous posts about the importance of celebrity role models in reducing stigma of various conditions. Besides their appearance on The View and their very honest portrayal on their show, they have also partnered with key professional organizations like Fertility Lifelines and Resolve- The National Infertility Association. They have created a PSA for Fertility Lifelines encouraging couples to visit a fertility specialist. They offer statistics to help normalize the struggle to conceive and to build a community by letting viewers now that they are not alone.

Just three days ago, Access Hollywood reported that actor Kelsey Grammer came forward to say that the pregnancy he and his girlfriend had just announced in August had ended in a miscarriage. It is hard to imagine that the culture is changing this quickly...in all my entertainment news watching, I can count on one hand how many celebrities have shared this type of story.

I also think that having a "spokescouple" increases the effectiveness of their message. The stigma of infertility so often falls to the woman. "What is wrong with her?" The woman also has to endure the physically and emotionally difficult treatments. Having a couple remind us via this PSA that it can be 50/50 as to which person (or both!) is leading to the infertility helps take the stigma off the woman alone.

This situation also makes me think about the systems (or lack there of) that exist to support couples once they make the choice to see a specialist. Are these types of specialists/procedures even covered by their health insurance? Is it difficult for couples to take time off of work to deal with the physical/emotional demands that come along with this process (which is so often completely inflexible in its scheduling)? Are human resource departments/managers supportive of making accommodations and/or keeping this information confidential for their employees? Are there enough mental health professionals that specialize in infertility to help couples/individuals with the emotional challenges that go along with the physical?

As more couples wait longer to have babies and science moves forward to offer more treatments for infertility, we're going to have to grapple with these questions on a broad system level. However, that conversation is easier to have when stigma is reduced and more couples come forward to ask for what they need and offer to help each other.

Sleep Post Correction

An astute commenter pointed out that I misread the numbers in the paper on sleep and fat loss. I wrote that out of the total 3.0 kg lost, the high-sleep group lost 2.4 kg as fat, and the low-sleep group lost 1.4 kg of fat out of 2.9 kg total.

In fact, the high-sleep group lost 1.4 out of 2.9 kg as fat, and the low-sleep group lost 0.6 out of 3.0 kg as fat. So I got the numbers all mixed up. Sorry for the mistake. The main point of the post still stands though: sleep deprivation negatively influences body composition.

The correct numbers are even more interesting than the ones I made up. Even in the high-sleep group, nearly half the body weight lost by simple calorie restriction was lean mass. That doesn't make calorie restriction look very good!

In the sleep-deprived group, 80% of the weight lost by calorie restriction came out of lean mass. Ouch!

That illustrates one of the reasons why I'm skeptical of simple calorie restriction as a means of fat loss. When the body "wants" to be fat, it will sacrifice lean mass to preserve fat tissue. For example, the genetically obese Zucker rat cannot be starved thin. If you try to put it on a severe calorie-restricted diet, it will literally die fat because it will cannibalize its own lean mass (muscle, heart, brain, etc.) to spare the fat. That's an extreme example, but it illustrates the point.

The key is not only to balance energy intake with expenditure (which the brain does automatically when it's working correctly), but to allocate energy appropriately to lean and fat mass.

Bullying: Is Technology Helping Us or Hurting Us?

Like many of you, my heart broke when I heard about the suicide of Tyler Clementi last week. Unsure of exactly how I wanted to focus my blog on this topic, I took a little time and read the comments coming through on Facebook and Twitter. I talked to colleagues and friends. And something that really struck me was that many people expressed that technology was the problem. All this new technology can only lead to bad things. Right? I agree that new technology has played a large part in our discussions around bullying the past few years. There seems to be an assumption on the part of the bullies that they can be protected by technology- that their identity can be kept "anonymous" in the cyber-world. Perhaps more kids bully online because it is easier to insult or hurt someone at that distance- versus right to their face. Of course, these hurtful comments or videos now have a much broader reach. They can be disseminated through the school, city, state, or even country in just minutes. And you can't take them back. I also think that technology is evolving so quickly that we don't always understand the new boundaries for privacy.

But even with all the new challenges and channels to bullying that technology brings, I still do not believe that it is the root cause. As a friend of mine tweeted this week (yes- Beth G you get a shout out here) "Thinking on the Tyler Clementi case. Tired of hearing that technology is to blame. I'm pretty sure Dharun Ravi and Molly Wei are, actually". Let's not forget the role of personal responsibility- I believe that gets lost when the blame falls squarely on technology.

So with all of that as a backdrop for this discussion, I decided that I wanted to focus my blog on how technology can also help us to combat bullying and help those at risk for suicide. Risk for suicide can increase among those who feel isolated and disconnected from resources. They can also suffer when surrounded by social norms that do not support help seeking for the resources that they need.

So I wanted to present these resources that have gone viral in just the past few days. I can't help but think about all the isolated kids/teens they may reach:

1. MTV launched an Iphone application to combat bullying called "Over the Line". Users can post a bullying scenario that they've experienced and other users can vote if it was "over the line". This has the potential to help promote positive norms/limits regarding how we treat each other. The peer support online may also encourage users to ask for help.

2. MTV was also involved in the launch of "Love is Louder". This "movement" has begun primarily in response to anti-gay bullying and suicides among LGBT youth. Viewers (and celebrities) can upload videos of support for these youth. It has been described as a way to channel the sadness and anger we all feel following these events. Again- this has the potential to build peer support among individuals that may be at risk. It also introduces celebrities or role models to support positive social norms.

3. Columnist Dan Savage has organized the "It Gets Better" campaign. The goal is to reach out to lesbian, gay, transgender and bisexual youth who may be the victims of bullying and remind/assure them that things will get better. This campaign has also attracted many celebrity supporters telling their stories (e.g., Tim Gunn from Project Runway was featured on many of my friends' Facebook pages today).

4. Four days ago, Ellen DeGeneres posted "An Important Message" on YouTube regarding the recent suicides of LGBT youth. As of tonight, there had been 235,627 views of that video. She pledged her support and encouraged all of us to have zero tolerance regarding bullying and the loss of these kids/teens.

So that's the complicated story. Technology brings new prevention challenges to bullying. But it can also build peer networks and deliver resources to those in isolation. It can bring the voice of celebrities or other role models into the discussion, which can be a strong influence on kids/teens. I urge us not to write off all technology in light of recent events.

For example, if anyone reading this blog needs help- please call the National Suicide Prevention Lifeline: 1-800-273-TALK (8255). Their technology even allows for Veterans to chat with an online counselor. Amazing!

The Big Sleep

This blog usually focuses on diet, because that's my specialty. But if you want Whole Health, you need the whole package: a diet and lifestyle that is broadly consistent with our evolutionary heritage. I think we all know that on some level, but a recent paper has reminded me of it.

I somehow managed to get on the press list of the Annals of Internal Medicine. That means they send me embargoed papers before they're released to the general public. That journal publishes a lot of high-impact diet studies, so it's a great privilege for me. I get to write about the studies, and publish my analysis at the time of general release, which is the same time the news outlets publish their stories.

One of the papers they sent me recently is a fat loss trial with an interesting twist (1; see below). All participants were told to eat 10% fewer calories that usual for two weeks, however half of them were instructed to sleep for 8 and a half hours per night, and the other half were instructed to sleep for 5 and a half hours*. The actual recorded sleep times were 7:25 and 5:14, respectively.

Weight loss by calorie restriction causes a reduction of both fat and lean mass, which is what the investigators observed. Both groups lost the same amount of weight. However, 80% of the weight was lost as fat in the high-sleep group (2.4/3.0 kg lost as fat), while only 48% of it was lost as fat in the low-sleep group (1.4/2.9 kg lost as fat). Basically, the sleep-deprived group lost as much lean mass as they did fat mass, which is not good!

There are many observational studies showing associations between insufficient sleep, obesity and diabetes. However, I think studies like that are particularly vulnerable to confounding variables, so I've never known quite what to make of them. Furthermore, they often show that long sleep duration associates with poor health as well, which I find highly unlikely to reflect cause and effect. I discussed one of those studies in a post a couple of years ago (2). That's why I appreciate this controlled trial so much.

Another sleep restriction trial published in the Lancet in 1999 showed that restricting healthy young men to four hours of sleep per night caused them to temporarily develop glucose intolerance, or pre-diabetes (3).

Furthermore, their daily rhythm of the hormone cortisol became abnormal. Rather than the normal pattern of a peak in the morning and a dip in the evening, sleep deprivation blunted their morning cortisol level and enhanced it in the evening. Cortisol is a stress hormone, among other things, and its fluctuations may contribute to our ability to feel awake in the morning and ready for bed at night.

The term "adrenal fatigue", which refers to the aforementioned disturbance in cortisol rhythm, is characterized by general fatigue, difficulty waking up in the morning, and difficulty going to sleep at night. It's a term that's commonly used by alternative medical practitioners but not generally accepted by mainstream medicine, possibly because it's difficult to demonstrate and the symptoms are fairly general. Robb Wolf talks about it in his book The Paleo Solution.

The investigators concluded:

Sleep debt has a harmful impact on carbohydrate metabolism and endocrine function. The effects are similar to those seen in normal ageing and, therefore, sleep debt may increase the severity of age-related chronic disorders.

So there you have it. Besides making us miserable, lack of sleep appears to predispose to obesity and diabetes, and probably sets us up for the Big Sleep down the line. I can't say I'm surprised, given how awful I feel after even one night of six hour sleep. I feel best after 9 hours, and I probably average about 8.5. Does it cut into my free time? Sure. But it's worth it to me, because it allows me to enjoy my day much more.

Keep your room as dark as possible during sleep. It also helps to avoid bright light, particularly in the blue spectrum, before bed (4). "Soft white" bulbs are preferable to full spectrum in the evening. If you need to use your computer, dim the monitor and adjust it to favor warm over cool colors. For people who sleep poorly due to anxiety, meditation before bed can be highly effective. I posted a tutorial here.

1. Nedeltcheva, AV et al. "Insufficient Sleep Undermines Dietary Efforts to Reduce Adiposity." Annals of Internal Medicine. 2010. Advanced publication.


* The study was a randomized crossover design with a 3 month washout period, which I consider a rigorous design. I think the study overall was very clever. The investigators used calorie restriction to cause rapid changes in body composition so that they could see differences on a reasonable timescale, rather than trying to deprive people of sleep for months and look for more gradual body fat changes without dietary changes. The latter experiment would have been more interesting, but potentially impractical and unethical.

Potatoes and Human Health, Part III

Potato-eating Cultures: the Quechua

The potato is thought to have originated in what is now Peru, on the shores of lake Titicaca. Native Peruvians such as the Quechua have been highly dependent on the potato for thousands of years. A 1964 study of the Quechua inhabitants of Nuñoa showed that they obtained 74% of their calories from potatoes (fresh and chuños), 10% from grains, 10% from Chenopodia (quinoa and cañihua), and 4% from animal foods. Total energy intake was 3,170 calories per day (1).

In 2001, a medical study of rural Quechua men reported an average body fat percentage of 16.4% (2). The mean age of the volunteers was 38. Body fat did increase slowly with age in this population, and by age 65 it was predicted to be about 20% on average. That's below the threshold of overweight, so I conclude that most men in this population are fairly lean, although there were a few overweight individuals.

In 2004, a study in rural Quechua women reported a body fat percentage of 31.2% in volunteers with a mean age of 35 (3). Body fat percentage was higher in a group of Quechua immigrants to the Peruvian capital of Lima. Among rural women, average fasting insulin was 6.8 uIU/mL, and fasting glucose was 68.4 mg/dL, which together suggest good insulin sensitivity and glucose control (4). Insulin and glucose were considerably lower in the rural group than the urban group. Blood pressure was low in both groups. Overall, this suggests that overweight is common among Quechua women.

Rural Quechua are characteristically short, with the average adult man standing no more than 5' 2" (2). One might be tempted to speculate that this reflects stunting due to a deficient diet. However, given the fact that nearly all non-industrial populations, including contemporary hunter-gatherers, are short by modern standards, I'm not convinced the Quechua are abnormal. A more likely explanation is that industrial foods cause excessive tissue growth in modern populations, perhaps by promoting overeating and excessive insulin and IGF-1 production, which are growth factors. I first encountered this hypothesis in Dr. Staffan Lindeberg's book Food and Western Disease.

I don't consider the Quechua diet to be optimal, but it does seem to support a reasonable level of metabolic health. Rural Quechua men subsisting on potatoes are relatively lean, while women are often overweight, though less overweight than urban Quechua who eat fewer potatoes. Unfortunately, I don't have more detailed data on other aspects of their health, such as gastrointestinal health.

Potato-eating Cultures: the Aymara


The Aymara are another potato-dependent people of the Andes, who span Peru, Bolivia and Chile. The first paper I'll discuss is titled "Low Prevalence of Type II Diabetes Despite a High Body Mass Index in the Aymara Natives From Chile", by Dr. Jose Luis Santos and colleagues (5). In the paper, they show that the prevalence of diabetes in this population was 1.5%, and the prevalence of pre-diabetes was 3.6%. The prevalence of both remained low even in the elderly. Here's a comparison of those numbers with figures from the modern United States (6):

That's quite a difference! The prevalence of diabetes in this population is low, but not as low as in some cultures such as the Kitavans (7, 8).

Now to discuss the "high body mass index" referenced in the title of the paper. The body mass index (BMI) is the relation between height and weight, and often, but not always, reflects fatness. The average BMI of this population was 24.9, which is very close to the cutoff between normal and overweight (25).

Investigators were surprised to find such a low prevalence of diabetes in this population, despite their apparent high prevalence of overweight. Yet if you've seen pictures of rural native South Americans, you may have noticed they're built short and thick, with wide hips and big barrel chests. Could this be confounding the relationship between BMI and body fatness? To answer that question, I found another paper that estimated body fat using skinfold measurements (9). That study reported that both men and women remained relatively lean throughout life (ages 4-65), with only two of 23 subjects classified as overweight on the basis of body fat percentage, and none classified as obese.

Back to the first paper. In this Aymara group, blood pressure was on the high side. Serum cholesterol was also a bit high for a traditionally-living population, but still lower than most modern groups (~188 mg/dL). I find it very interesting that the cholesterol level in this population that eats virtually no fat was the same as on Tokelau, where nearly half of calories come from highly saturated coconut fat (10, 11). Fasting insulin is also on the high side in the Aymara, which is also interesting given their good glucose tolerance and low prevalence of diabetes.

This shows that a lifetime of high-carbohydrate, high-glycemic food does not necessarily lead to overweight or metabolic problems in the context of a traditional diet and lifestyle.

Potato-eating Cultures: the Irish

Potatoes were introduced to Ireland in the 17th century. They were well suited to the cool, temperate climate, and more productive than any other crop. By the early 18th century, potatoes were the main source of calories, particularly for the poor who ate practically nothing else. In 1839, the average Irish laborer obtained 87% of his calories from potatoes (12). In 1845, the potato blight Phytophthora infestans struck, decimating potato plantations nationwide and creating the Great Famine.

There isn't much reliable information on the health status of the Irish prior to the famine, besides reports of vitamin A deficiency symptoms (13). However, they had a very high fertility rate, and anecdotal reports described them as healthy and attractive (14):

As far as fecundity is concerned, the high nutritional value of the potato diet might have played a significant role, but little supportive evidence has been presented so far... What is known is that the Irish in general and Irish women in particular were widely described as healthy and good-looking. Adam Smith's famous remark that potatoes were "peculiarly suitable to the health of the human constitution" can be complemented with numerous observations from other contemporary observers to the same effect.

Controlled Feeding Studies

Starting nearly a century ago, a few scientists decided to feed volunteers potato-only diets to achieve various research objectives. The first such experiment was carried out by a Dr. M. Hindhede and published in 1913 (described in 15). Hindhede's goal was to explore the lower limit of the human protein requirement and the biological quality of potato protein. He fed three healthy adult men almost nothing but potatoes and margarine for 309 days (margarine was not made from hydrogenated seed oils at the time), all while making them do progressively more demanding physical labor. They apparently remained in good physical condition. Here's a description of one of his volunteers, a Mr. Madsen, from another book (described in 16; thanks to Matt Metzgar):

In order to test whether it was possible to perform heavy work on a strict potato diet, Mr. Madsen took a place as a farm laborer... His physical condition was excellent. In his book, Dr. Hindhede shows a photograph of Mr. Madsen taken on December 21st, 1912, after he had lived for almost a year entirely on potatoes. This photograph shows a strong, solid, athletic-looking figure, all of whose muscles are well-developed, and without excess fat. ...Hindhede had him examined by five physicians, including a diagnostician, a specialist in gastric and intestinal diseases, an X-ray specialist, and a blood specialist. They all pronounced him to be in a state of perfect health.

Dr. Hindhede discovered that potato protein is high quality, providing all essential amino acids and high digestibility. Potato protein alone is sufficient to sustain an athletic man (although that doesn't make it optimal). A subsequent potato feeding study published in 1927 confirmed this finding (17). Two volunteers, a man and a woman, ate almost nothing but potatoes with a bit of lard and butter for 5.5 months. The man was an athlete but the woman was sedentary. Body weight and nitrogen balance (reflecting protein gain/loss from the body) remained constant throughout the experiment, indicating that their muscles were not atrophying at any appreciable rate, and they were probably not putting on fat. The investigators remarked:

The digestion was excellent throughout the experiment and both subjects felt very well. They did not tire of the uniform potato diet and there was no craving for change.

In one of his Paleo Diet newsletters titled "Consumption of Nightshade Plants (Part 1)", Dr. Loren Cordain referenced two feeding studies showing that potatoes increase the serum level of the inflammatory cytokine interleukin-6 (22, 23). However, one study was not designed to determine the specific role of potato in the change (two dietary factors were altered simultaneously), and the other used potato chips as the source of potato. So I don't find these studies particularly relevant to the question at hand.

Just yesterday, Chris Voigt of the Washington State Potato Commission embarked on his own n=1 potato feeding experiment as a way to promote Washington state potatoes. He'll be eating nothing but potatoes and a little fat for two months, and getting a full physical at the end. Check out his website for more information and updates (18). Mr. Voigt has graciously agreed to a written interview with Whole Health Source at the end of his experiment. He pointed out to me that the Russet Burbank potato, the most popular variety in the United States, is over 135 years old. Stay tuned for more interesting facts from Mr. Voigt in early December.

Observational Studies

With the recent interest in the health effects of the glycemic index, a few studies have examined the association between potatoes and health in various populations. The results are all over the place, with some showing positive associations with health, and others showing negative associations (19, 20, 21). As a whole, I find these studies difficult to interpret and not very helpful.

Anecdotes

Some people feel good when they eat potatoes. Others find that potatoes and other members of the nightshade family give them digestive problems, exacerbate their arthritis, or cause fat gain. I haven't encountered any solid data to substantiate claims that nightshades aggravate arthritis or other inflammatory conditions. However, that doesn't mean there aren't individuals who are sensitive. If potatoes don't agree with you, by all means avoid them.

The Bottom Line

You made it to the end! Give yourself a pat on the back. You deserve it.

In my opinion, the scientific literature as a whole, including animal and human studies, suggests rather consistently that potatoes can be a healthy part of a varied diet for most people, and they probably do not generally promote digestive problems, fat gain, or metabolic dysfunction.  Nevertheless, I wouldn't recommend eating nothing but potatoes for any length of time. If you do choose to eat potatoes, follow these simple guidelines:

• Don't eat potatoes that are green, sprouting, blemished, or damaged
• Store them in a cool, dark place. They don't need to be refrigerated but it will extend their life
  
• Peel them before eating if you rely on them as a staple food
  

Enjoy your potatoes!