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Interview with Dr. Robert Rucker about Nutrition and Academics

Dr. Robert Rucker is a Distinguished Professor Emeritus in the Department of Nutrition and the School of Medicine at the University of California at Davis. A list of his accomplishments include tenure as the President of American Society for Nutrition, an American Association for the Advancement of Science Fellow, as well as an American Society for Nutrition Fellow. Dr. Rucker has over 35 years of experience researching nutrition and biochemistry. He is also my father and is the ghostwriter for almost all of the pyrroloquinoline quinone (PQQ) content found on this website.


1) One of the debated topics in nutrition is whether weight management is really just a matter of calories in/calories out; or alternatively, significantly influenced by the types of calories that are consumed. Based on your rich understanding of nutrition and biochemistry, where have you landed on this debate?

This question is not as easy to address, as some would make it.  Energy regulation – the factors associated growth, work, and maintenance of body temperature – is complex and multifaceted.  Clearly when energy intake is less than needed, body tissue becomes a metabolic energy source; however, weight gain or loss as inferred from periodically weighing oneself on a scale is not a function of a simple algorithm, particularly in the short-term.  As it relates to weight gain or loss of body tissue, each of the major components contain differing amounts of energy.  For example, a pound of stored fat is ~ equivalent to 3600 kCal per pound.  Muscle tissue is the equivalent of 700-800 kCal per pound.  Independent of its water content, a well-nourished adult has about 400-500 grams or 1600- 2000 kcal of stored carbohydrates, mostly as liver and muscle glycogen.  When or how much of a given tissue is utilized as energy sources varies depending on the timing of meals, exercise, and a need to maintain body temperature. Utilizing tissue energy also causes varying amount of water release. Thus, 2-3 days of severe dieting (e.g., generating a 3000-4000 kCal deficit) could translate into a one-pound loss or a 5-7 pound loss, as measured on a bathroom scales, depending on factors in addition to only estimating calories-in minus calories-out.

Regarding diet composition, there are a number of scenarios wherein the composition of food also plays a role in net weight gain and loss.  An obvious one is a diet high in simple sugars, particularly fructose or high fructose corn serum (HFCS).  Our knowledge of the control energy homeostasis has increased dramatically over the last decade resulting in an appreciation that food or energy intake is orchestrated by complex signals originating from adipose tissue, the pancreas, and the gastrointestinal tract, plus others.  Differences in food composition can affect these signals, which in turn can influence food intake and body heat regulatory circuits.   With respect to fructose or HFCS, both are weak stimulators of insulin and the adipose-derived hormones that control food intake, in contrast to glucose, a much stronger stimulator.  Moreover, although fructose is eventually converted to glucose, the process is not rapid and fructose, as such, is not “stored”.  And, fructose is a better “driver” of triglyceride synthesis than glucose.  Add to this that body heat regulation is very precise.  Compounds, such as fructose, that are rapidly absorbed and are not easily sequestered or rapidly metabolized can compromise body heat regulation.  Thus, calories from fructose or HFCS are less likely to allow one’s metabolic system to regulate itself at least in the short term. 

What can happen? The liver slows oxidative metabolism when there are energy excesses, particularly if an abnormal elevation in the body core temperature can result.  What the liver may perceive as an excess of potentially hazardous fructose-derived calories are converted to triglyceride and next sequestered away in adipose as a protective strategy.  In this regard, some of the energy derived from fructose is rendered ‘out of the picture’ and may even result in some weight gain, because of its conversion and “storage” as fat.  

Again, these kinds of questions are not easily addressed.  An example that I sometimes use in lectures is that over the course of a year, most in the class will consume anywhere from ~ ½ to one million calories (at a daily expenditure of  ~1500 to 2500 kCal per day, which translates into consuming a ~ton of food per year).  Given that an annual normal weight gain or loss is usually no more than a pound or two, it says a lot about the exquisite precision of food intake regulation, as well as body mass and heat regulation.  Throw in dozens of genetic factors and other variables and it is easy to ascertain that there are good reasons for controversy and our inabilities to address (easily) weight management when it deemed important.

2) Given all that you have researched, what are the three most impressive compounds you have come across (other than PQQ)? You can choose either based on their historic significance and/or the fact you have been impressed by their demonstrated physiological benefit.

In the late 1700s – Antoine Lavoisier, the so-called “Father of Nutrition and Chemistry” described that metabolism and oxygen were inexorably linked.   He also demonstrated oxygen was related to animal heat production.  Accordingly, oxygen would be one of the molecules.  In the latter part of my career, concepts related to cell signaling and secondary signaling molecules begin to be major influences.  As a consequence, Nitric oxide (NO) and 3′-5′-cyclic adenosine monophosphate are two others that I would add.  NO is an important cellular signaling molecule involved in many physiological and pathological processes; cyclic-AMP works in part by triggering the activation of certain proteins involved in cell signaling.  Knowledge regarding their underlying mechanisms of action facilitated my way of thinking about the mechanisms of action of certain dietary biofactors, such as pyrroloquinoline quinone (PQQ).

3) As the world increasingly points to poor nutrition for the rise in healthcare costs, little has been done to improve the nutritional education in top-tier medical schools. You were a nutrition professor at a top-tier medical school. Why do you think this is?

A part of the answer is that there is no medical board certification for nutrition.  There are 24 boards that certify physician specialists.  Many hospitals demand that physicians must be board certified to practice or bill for a specialty.  Accordingly, when there are nutritional issues, they are usually handled by a paramedical (i.e. a dietitian or a nurse) or occasionally a pharmacist with nutrition as a sub-specialty.

With that said, many medical schools do give nutrition training some kind of “lip-service”, although it is often less than it used to be. Most medical schools have moved to more integrated curricula and problem-based learning. At Davis there used to be a strong course in nutrition, but as the Davis medical school curriculum became more and more integrated, the visibility of nutrition was truncated.  Regrettably, as long as nutrition remains as a non-board certified area, I don’t sense that there will be a move to make nutrition more visible, even though there is seldom an argument regarding its importance.

4) On the topic of research, some of the fondest conversations I’ve had with you are discussions regarding the thoughts of intellectuals who take either side of Thomas Kuhn’s work. We have discussed articles like The Truth Wears Off and books like Laboratory Life. Do you think there is “real world” truth to be found, or do you think as seekers of the “truth” we are tasked with inventing it?

As a starting point, I agree with Kuhn’s premise that scientific advances are characterized by dynamic shifts in thinking, i.e. what he defines as paradigms,  ” universally recognized scientific achievements that, for a time, provide model problems and solutions for a community of practitioners”.  In my life time, the major paradigm shifts that have most influence my thinking as a biologist have been: 1) the Watson and Crick model of DNA and its importance, 2) concepts related to cell signaling, 3) concepts important to epigenetics (changes in metabolic regulation caused by gene expression rather than an alteration of the genetic code itself), 4) polymorphisms  (metabolic changes caused by point mutations in a gene or genes), and descriptions based on metabolic allometric scaling (ways of describing how the characteristics of living creatures change with size).  If I were to note more fundamental principles – Darwinian evolution, the principles of thermodynamics applied to biology, and the concept of nutritional essentiality in the context of given nutrients or metabolic processes would be at the top of the list.  Each of these paradigms can be described historically in the context of Kuhn’s stages of scientific development, which ends with the establishment of concepts that truly influence changes in how we think about a problem.

Regarding ‘Are there real world truths to be found?’ I certainly hope so. However, to find such truths, I would argue that one has to engage in clear rational thinking directed at seeking out evidence for the truth; a process along the lines of what Richard Dawkins implies, when he emphasizes the importance of asking the right question.  In contrast, inventors of “truth” in my experience tend to be more concerned with faith, authority, or profit (in a broad context).

Although far less philosophical, the Jonah Lehrer article in the New Yorker, The Truth Wears Off, also provides some very important perspectives that – as you note – have been the topic of several of our discussions.  With respect to nutrition, this has been an interesting period, particularly as it relates to the assessment of validity and reliability of certain nutrition-related assertions and their presumed relationship to important health issues.  In some instances, our lack of rational thinking has caused some “true believers” to promise too much.  For a premise to become health policy, the data and observations behind it must be reliable and reproducible.  Unfortunately, we too often let belief and personal perceptions over ride the facts of a given question or premise. 

With regard to why there is so much controversy as it relates to nutrition, some reasons that are developed in the Lehrer article, such as those offered by John Ioannidis (e.g., Why most published research findings are false. 2005; PLoS Med 2: e124) are provocative.  However, they are mostly statistically in nature.  Now that we have larger and presumably better databases and better tools to examine them, plus the ability to ask better questions, it should not be surprising that some amount of previously published research may not be easily or consistently replicated.

I tend not to throw barbs, if the studies in question are complex in nature and initially were carried out for a good purpose.  As an example – In studies of osteopenic bone diseases, such as osteoporosis, the highest rates for hip fracture, as an outcome measure, are often observed in those of Scandinavian decent, who are located predominately in the North Central parts of the US. The lowest rates for hip fracture are observed in those of African decent, who are located predominately in the South.  Consequently, it is not unreasonable to surmise that observations related to hip fractures made 3-4 decades ago in studies performed in Minnesota or North Dakota may not match the results of similar studies, if repeated using a contemporary and highly diverse Californian or Floridian based subject pool, some of whom may be a blend of an identifiable Scandinavian and African-derived gene pool. Further, studies for purposes of comparisons are often difficult to match with respect to the age, sex, and/or activity levels of subjects.  It is now more difficult to control environmental and epigenetic factors than in the past, because of our ability and freedom to travel or consume more diverse diets.  With more genetically diverse subject populations and more complexity in lifestyle, there is greater likelihood that there may be regression to some kind of statistical mean, i.e. less significance noted in a study than may have been noted previously. 

Other issues are barriers that we have rightly put into place for the protection and more ethical treatment of subjects. For example, many of the early paper regarding basic human nutritional requirements were reasonably correct in their conclusions.  However, the studies were often performed using institutionalized individuals (prisoners or mental patients) who could be studied for long periods or subjected to metabolic risks using protocols that simply cannot be used today. 

The ways that we report and characterize research can also present problems. Current research often uses past research as a potential starting point or platform, i.e. Kuhn’s second level of discovery before an actual paradigm emerges.  However, most research (past and present) is/was not published unless its outcome demonstrates some type of statistically significant positive effect.  It is the common practice of most journals not to publish null or negative observations.  Again, it is not unreasonable that some current replications of past work may differ, particularly when there is a better sampling of subjects and use of improved analytical methods. 

More troubling to me is the mismanagement of data by those who should know better.  The reason why some health-oriented work cannot be reproduced is because it is the product of data dredging designed mostly to identify relationships with some arbitrary level of statistical significance. If the “data dredge” is merely a search for statistical significance, it is too easy to make wrong inferences.  There is little wrong in using an arbitrary statistical endpoint to better define a hypothesis or question, but to report such findings as facts without some type of independent conformation or validation is disingenuous at best.  More egregious, of course, is reporting only selected data in order to show some kind of statistically positive effect.  There is also dishonest reporting.  When I was more involved in journal editing and management, it was troubling to discovery that work using the same pool of subjects had been published in different formats in other journals.   The issue was not so much self-plagiarism or lack of consolidation; rather, it was the implication that the observation submitted to a given journal was from different sets of independent observations. The number of independent research papers on a given substance is sometimes used as a measure that the product is safe or efficacious. One may have a different opinion of efficacy or safety with the knowledge that the reported data was from a single set of subjects, rather than multiple independent sets of subjects and each reported in separate papers.

Regrettably, the commercial nutritional supplement business is perhaps the worst offender.  Very little research is done independently and most often is driven by marketing goals.  As we now know, it is possible to buy the results that you might want from some of the commercial research outlets for publication in one of the dozens of online journals, many of which serve as “vanity presses”.  The other areas that compromise good nutritional practice are the constraints placed on the policing of the supplement industry, because of the Dietary Supplement Health and Education Act and the impact of having it as a part of our National Institutes of Health, a National Center for Complementary and Alternative Medicine.  The Center’s goal is to support research and provide information about complementary health products and practice, but what it defines as evidence-based medicine often isn’t, and credibility is given to alternative concepts, where little is deserved.

5) Piggybacking off that, as I embark on my own journey aspiring to be an expert in the field of workplace wellness, based on your vast experience, what advice can you pass down to me as I continue the search for “truth” with a drive to contribute to the greater good?

Success, particularly the effective movement of ideas, is all about “networking”.   Bruno Latour and Steve Woolgar clearly make this point in their book, LABORATORY LIFE: The Construction of Scientific Facts. I was lucky enough to be mentored by individuals who can trace their academic history back to those who discovered or defined the functions of given vitamins or nutritionally essential minerals.  What was transferred to me, as a part of that network, was a way thinking; also the importance of maintaining a high integrity. It is also essential to have a thought out, as well as thoughtful, work plan; and, as Latour and Woolgar note, one’s credibility rests on whether you are perceived as reliable.  The challenge is to maintain integrity in workplaces (e.g., the commercial aspects of nutrition and wellness) that often talk about integrity and validly, but seldom want to test for it, and that are driven in large degree by the marketing of what are sometimes shallow promises.