Nutrition experience, research, and orthodoxy, with some economics parallels

Lynne Kiesling

Last week was our spring break, and I finally took some time to read Gary Taubes’ 2008 book Good Calories, Bad Calories. Taubes is an investigative science journalist who has been writing for years about the science of nutrition and epidemiology, and the book focuses on a long, careful, detailed narrative about how such science has evolved since the mid-19th century. One of the themes that emerges is that some of the most prominent researchers, particularly those advancing the dual hypotheses that fat causes heart disease/overeating causes obesity, did not test their hypotheses for falsification using controlled trials in designing their research, and are also personally invested in doing research that “proves them right”. Thus, Taubes argues, an orthodoxy has formed around these hypotheses when he finds the scientific support for them lacking, and similarly finds support for an alternate hypothesis — refined carbohydrates cause heart disease and obesity. But the orthodoxy resists testing that alternate hypothesis.

I have personal interest in this topic based on my own experience. As a high metabolism athlete for all of my life, I grew up being able to eat almost anything in unrestricted quantities. But when I got my first faculty job out of grad school (at WIlliam & Mary, yay!) in 1992, the combination of teaching and research duties with moving to a swampy climate against which my body rebelled meant a reduction in my activity, bloating because of the humidity, and weight gain. Without really thinking about it (because I hadn’t had to before), I reduced my meat consumption and substituted into (refined and unrefined) carbs. The next two years were right out of Taubes’ book — reduction in calories to manage weight while increasing exercise, but not having enough energy to actually make it meaningful, culminating in what is now known as metabolic syndrome complete with insulin resistance, hormone imbalance, and symptoms of polycystic ovarian syndrome. I then spent two years revamping my diet to reduce refined carbs, include more animal and vegetable protein at every meal, and monitor my hormone and energy levels, and succeeded in reversing all negative symptoms. I returned to the energy levels that have enabled me to do longer and longer distance cycling and triathlon endurance events and the demanding training for them. Even though I don’t eat low-fat, my triglycerides are so low that my doctor marvels at it. Taubes’ argument is consistent with my experience.

Economist Russ Roberts has been experimenting with his diet and exercise for the past six months, following broadly the same principles that I do (including the refined carbs on the weekend), and he reported in on Friday: 20 pounds lost, more energy, feeling of satiation, low triglycerides. Again, consistent with my experience.

You may know Russ for his outstanding EconTalk podcast series, and in November 2011 he interviewed Gary Taubes. The conversation was interesting and informative, and the podcast page lists lots of resources for further reading. One theme that Russ developed in the discussion was that in both nutrition research and economics research, the issues come up of orthodoxy and structuring research questions in ways that generate falsifiable hypotheses when you are studying such a complex, dynamic system as either the human diet/cardio/endocrine system or the human economy. The human traits that incline us toward orthodoxy, whether it’s wanting to prove ourselves right or appeal to authority or some other trait, have led to models and hypotheses that are not supportable or not even meaningfully testable/falsifiable. So for me reading Taubes’ book was a good cautionary tale of the value of humility beyond the analysis of low-carb/low-fat nutrition.

Another insight that comes up in the book that I would add to Russ’ comparison with macroeconomics is heterogeneity. Taubes is careful to point out that individuals have different metabolic experiences and achieve homeostasis with different combinations of fat, carbs, etc., so while low-carb nutrition may allow some people to strike a healthy heart and weight balance, others may be able to eat more carbs and do the same. Heterogeneity means that there’s no one-size-fits-all hypothesis … and as any Austrian macroeconomist will tell you, that’s the argument they put forth about macroeconomic models and aggregation. Heterogeneity in the capital structure in reality means that models abstracting from such heterogeneity are more likely to mislead.

Spring weekends in Chicago–athletics and music edition

Lynne Kiesling

One of the KP Spouse’s and my best friends has a great quote: “adventure is ordeal retold at a distance”. Today, on a gloriously sunny day, I think I’ve got enough distance from yesterday’s ordeal to think of it as an adventure! Actually, only the first part was an ordeal; the rest was delightful.

Sunday started at 5:15 AM when the alarm went off, and the KP Spouse, our friend Meg from LA, and I prepared for the Chicago Spring Half Marathon. When we opened the blinds and saw the damp pavement and the vigor of the treetops whipping around, we knew this one was going to be a doozy. The temperature was 46 degrees and due to fall during the day. The whitecaps and the layers of gray colors made Lake Michigan look like the Atlantic Ocean. Sadly for us, what creates whitecaps in Chicago is stiff winds out of the north barreling down the length of the lake — in this case, 20mph winds with frequent 40mph gusts. This was not good news for a race course run entirely on the lakefront path, out and back, with the first 6.5 miles heading south. The tailwind on the way out was pretty sweet, but I was still soaked through by mile 5, and the northbound return was the most brutal hour-plus of any of my sporty endeavors. Still, we (and a bunch of other crazy folks) finished, and I even managed a PR on the day. The real troopers on the day were the volunteers on the course and the spectators, voluntarily cheering their friends and family and the rest of us.

Recovery/transition involved homemade banana pancakes, a lovely bottle of prosecco, compression socks, and a Colin Firth-rich Pride and Prejudice marathon.

Then on to the next event! Elvis Costello, still the coolest guy in town even after 35 years of a rich musical career, brought his Impostors and a spinning wheel of songs to the Chicago Theater. With the help of some creative and enthusiastic wheel spinning and dancing from audience members, they charged through a variety of the Elvis Costello catalog. And we danced, and hopped, and sang. This is the third time I’ve seen these guys in the past three years, and they are a consistently creative and tight band of outstanding musicians. One example: the classic up-tempo Costello song “Pump It Up” played in 6/8 time instead of 4/4 — a sultry, jazzy version grounded in Pete’s (the drummer’s) outstanding triplets keeping the time. And some Smokey Robinson and Prince cover medleys for good measure.

Yep, life’s an adventure.

John asked for a cycling post …

Lynne Kiesling

… but this is an econ post too. John Whitehead was kind to refer to our November lunch conversation in which we discovered a shared interest in cycling (to go along with our shared interests in economics, environmental economics, and beer). There are some ways that even individual recreational cycling reflects core economic ideas, particularly about specialization and comparative advantage (don’t even get me started on the economics and strategy of professional cycling …).

Take the duration of activity, for example. From exercise physiology we learn that we have differentiated muscle fibers, categorized roughly into fast twitch and slow twitch. Fast twitch are the muscle fibers that engage for quick bursts, working with the anaerobic energy system in sprints and other short but intense activities. Slow twitch are the muscle fibers that enable you to work aerobically, over long distances and durations. Different people possess these types of muscle fibers in different proportions (think of that as your initial endowment), and you can develop more of one or the other at the margin, but given your initial endowment, you are going to have a predisposition toward one or the other. Just as in talking about trade and exchange, this predisposition has a lot to do with comparative advantage.

More after the cut … Continue reading

Back from the Birkie

Lynne Kiesling

This weekend the KP Spouse and I headed six hours north into northwest Wisconsin and joined a cabin-full of friends in the American Birkebeiner cross-country ski race, although my pace was not so racelike! We did the half distance (the Kortelopet), which is 23km (14.26 miles), classic style (i.e., not the skate style that you’ve been seeing on the Olympics). I was slow, even slower than my running pace, but it was a gorgeous course and the weather was beautiful. In terms of fitness I was in good cardiovascular shape for it (and from a cardio perspective could have done the full 54km Birkie), but my x-c skiing technique is poor, and it sure did challenge my muscles! My natural tendency is fast-twitch muscle activity and things like downhill skiing, so long-distance cross-country slow-twitch endurance is not my thing. But it was fun, especially the big party in Hayward afterward and then pizza that night with our party … although I am sure having some trouble moving today!

Research mounts showing Vitamin D’s health benefits

Lynne Kiesling

Over the past year or so I’ve been following the debate and research on Vitamin D intake. Initially Vitamin D supplementation was recommended simply to reduce the incidence of rickets in children, but increasingly Vitamin D is associated with a wide range of health benefits, from reducing fatigue to improving metabolism to improving heart health. Vitamin D has become a particular challenge in the past 30 years, because we’ve gotten out of the stereotypical “spoonful of cod liver oil” that was popular in the early 20th century (fish oils are rich in Vitamin D and in omega-3 and omega-6 fatty acids that are good for metabolism and for the heart). At the same time, we’ve increased our use of sunscreen, and since almost no foods are rich in Vitamin D, the primary way to get it is to expose your skin to sunlight for 10-60 minutes per day, depending on time of year (less in summer, more in winter). Sunscreen blocks Vitamin D absorption while protecting us from skin cancer.

This week a new study was released and presented at the American Heart Association meetings, as reported in this Yahoo/AP story and this longer New York Times story. As the NYT summarized the results:

In the study, researchers looked at tens of thousands of healthy adults 50 and older whose vitamin D levels had been measured during routine checkups. A majority, they found, were deficient in the vitamin. About two-thirds had less vitamin D in their bloodstreams than the authors considered healthy, and many were extremely deficient.

Less than two years later, the researchers found, those who had extremely low levels of the vitamin were almost twice as likely to have died or suffered a stroke than those with adequate amounts. They also had more coronary artery disease and were twice as likely to have developed heart failure.

The findings, which are being presented today at an American Heart Association conference in Orlando, don’t prove that lack of vitamin D causes heart disease; they only suggest a link between the two. But cardiologists are starting to pay increasing attention because of what they’re learning about vitamin D’s roles in regulating blood pressure, inflammation and glucose control — all critical body processes in cardiovascular health.

The article goes into much more detail about the study, and is a very worthy read.

The sports nutrition community have also been paying attention to Vitamin D for a while, and these new results reinforce the idea that Vitamin D levels are an important factor in athletic performance, in addition to overall health. This article from Competitor discusses the role of Vitamin D in fatigue in endurance athletes, something that we frequently attribute to iron deficiency instead (especially in women), but it may be that Vitamin D is a culprit too. The author, a dietitian, summarizes some sports research on Vitamin D levels:

This was my very first experience with vitamin D deficiency and I have since learned that vitamin D deficiency is becoming an epidemic worldwide, not only in geographic regions where sun exposure is limited.  And my discussions with fellow dietitians working with college runners and professional athletes in generally sunny states (Texas and Florida) confirmed the alarming prevalence of vitamin D deficiency across ethnicity and gender.

Athletes who live in northern latitudes (north of 35 degrees), or use sunscreen consistently, perform their sport indoors, or keep their skin covered are at the greatest risk.  Melanin affects the production of vitamin D.  So those with more melanin or darker skin produce less vitamin D.  Since vitamin D is a fat-soluble vitamin, athletes with fat malabsorption problems such as cystic fibrosis, Crohn’s disease, and celiac disease are at risk for deficiency.  Those who have normal levels typically (around 50 ng/ml) live in sub-equatorial Africa and work outdoors for most of the summer.

Once thought of as being primarily involved in bone development, activated vitamin D (calcitriol), a steroid hormone, is responsible for regulating more than 1000 human genes.  Almost every cell in the human body has receptors for vitamin D.  Recent research shows that vitamin D deficiency increases the risk of different types of cancer (such as breast cancer and prostate cancer), as well as heart disease, diabetes, depression, autoimmune diseases, hypertension, obesity, gum disease, chronic pain, muscle wasting, inflammation, birth defects, osteoporosis, influenza and colds, etc.

So here’s my public service announcement for the day: at your next annual checkup when you order your blood work, ask to have your Vitamin D levels tested. And think about the sunscreen-Vitamin D tradeoff; getting 30 minutes of unobstructed sun is unlikely to increase skin cancer risk enough to outweigh the Vitamin D benefits from the sun absorption. Vitamin D supplementation is also low-risk; I figure between my multi and my fish oil and my Vitamin D I get about 800 IU, and I have noticed decreases in my fatigue levels.