Your text defines Nutrition as “a science that centers on foods, their nutrient and other chemical constituents, and the effects of food constituents on body processes and health” (pg 1-6). This definition requires that we utilize scientific reasoning and methods to examine the issues of how food contributes to physiology and supports wellness, and the physiological mechanisms which convert food to nutrients for absorption and distribution to body tissues. Thus, we begin, where almost all introductory science books begin, with a very brief discussion of the nature of the science enterprise.
For this series of lectures, we are concerned with the Science of Nutrition. In order to understand
how the science of Nutrition differs from Nutrition as urban legend, we need to remember a
few of the characteristics of Science. The two characteristics of Science
which are the most important to this course are
(a) we like to state our assumptions explicitly and to define our terms carefully, and
(b) we demand experimental verification of our “theories.”
There are a few assumptions which are sufficiently important to your motivation to learn
Nutrition “independently” that you need to know what they are, and hopefully keep
them in mind should you become frustrated with the independent study approach taken here.
Specifically, I assume:
a. You are taking this course in the hopes of learning more about Nutrition (I assume this because I am naive enough to think that my students want to learn, even if other professors' students don't.)
b. You actually remember some of what you memorized for A&P – both Anatomy and Physiology!
c. You must understand the physiology of nutrients in order to explain good nutrition habits to your future patients.
d. Adequate nutrition [and other life style choices, some of which are included in the lectures] provides longer life, …and more importantly, better quality of life during the extended life span; in other words, contributes to “Wellness.”
e. Life span begins before birth, at conception, so the contribution of nutrition to wellness begins with the egg which is about to be fertilized.
We shall start with an example to illustrate how we can define commonly understood words to have
particular, and even peculiar, meanings:
“interesting:” most professors and other teachers I have encountered seem to use this word as if it meant “anything I find to be interesting is intrinsically interesting; so, all of my students should find it to be interesting as well.” Almost none of the students I have encountered agree, except they too use the word the same way (while the professor is talking at great length about something clearly not interesting, the students engage in activities [such as texting their friends] which the students consider to be interesting).
There are a several definitions needed for this course. For the most part, these are terms which we use in a highly restricted sense, although they may have broader meanings which are probably familiar to you. Most of the definitions we need will be introduced in the context where we first use the term. We shall start with two, paraphrased from the introductory chapters of several textbooks, because they define the overall subject matter of the course:
a. Nutrition: 1. “the scientific study of foods, their nutrient (and other chemical) constituents, and the effects of nutrients on body processes and wellness.” 2. “the collective sum of all chemical substances in food which affect body processes and/or wellness.”
b. Diet: 1. “a plan for food intake within a defined time period.” The plan may be driven by specific short term goals, such as losing too much weight in too little time, which is unfortunately what most Americans think of when they hear the term “diet”. Nutritionists prefer the diet as a plan driven by general long term goals, such as maintaining a good quality of live beyond age 90. 2. The other common usage is that it is an accounting of foods consumed [frequently by a group] over some past time interval, which is not a plan at all. This is like the budget which many people think means writing down all expenditures for last month, while financial advisors consider a budget to be a plan for how to spend next month's money.
Scientists tend to distinguish between fact and explanations because, in Science, facts are
‘true,’ while explanations can be challenged. For facts to be always true, the concept
of a fact must be restricted to things that cannot be untrue, based on what we know today. The way
I use the term fact it refers to “anything which is
observable.” To be ‘observable’ means that in could be observed, not
necessarily that it has been observed by me personally. If something has been reported as
observed by a reliable observer, then I consider it to be observed. Note: you, the student, are
by definition a reliable observer. When you report observations to me, the reported observations
become facts. Facts by my definition include those observed indirectly as well as directly. For
example, we can use an electron microscope to look at details much smaller than cells, although most
of us have difficulty observing whole cells directly (with the naked eye). You should note also
that my definition limits facts to a collection of rather boring bits of information accumulated
in your life time.
An explanation is “an attempt to explain a set of facts.” Using this definition, ‘sunset’ is an explanation of the set of facts collected over several minutes: (1) the sun was observed above the horizon, then (2) the sun was partially obscured by the horizon, then (3) the sun was completely obscured by the horizon. Technically, for the sun to ‘set’ the Sun must move around the Earth, which few scientists currently believe! An explanation (of our three facts) more consistent with our current explanation of how the Universe works would be that ‘horizonrise’ has occurred. However, I doubt seriously that very many couples would be inclined to sit on the beach together to watch the horizon rise. Another example to illustrate the difference between [boring] facts and ‘interesting’ explanations is the controversial issue of global warming/climate change. Systematic weather observations (temperature, precipitaion, etc) have been taken since Nov 1, 1870, when 24 telegraph stations read their instruments [distributed by the Smithsonian Institution to 150 telegraph stations in 1848] at the same time and sent the results to the government office which later became the National Weather Service. Later, similar networks were established in Europe (and even later in the rest of the world). Change in climate over the 136 years between the start of weather data collection and 2006 (release of the documentary film, An Inconvenient Truth) is fact because it was observed. Everything else in the film is an attempt (by Al Gore) to explain the facts. When we, as Scientists, use scientific methods to arrive at our explanations, the explanation is called a hypothesis, which is defined as “an ‘educated guess’ at explanation.” This is discussed at annoying length in § 3 below.
Another type of explanation you will encounter frequently in discussions of Nutrition, diets, and wellness is the claim, which is “the assignment of some characteristics, often to a product or to a program of behaviors.” These claims may or may not be supported by fact(s). Sometimes, but not usually, they may be hypotheses [in the sense described below] presented as facts. Examples of claims include the claim that vitamins can be applied to dead skin layers of the epidermis (or to hair shafts) to nourish the dead cells (or protein molecules of the hair shafts) and rejuvenate them, which cannot happen because dead cells are dead. Some herbal products are claimed to cause weight loss without change in quantity of food intake, change in nutrient density of food, nor increase in exercise activity. The key to determining whether or not the claim is supported by research is [obviously] citation of the research [supported], or supported by testimonials by happy customers [no evidence of research support]. You need to know that all such testimonials are paid [most often in free, or discounted products].
As scientists, we tend to guess at the answers [what we just defined as ‘explanations’]
a lot. We, of course, would prefer that you didn't know that, so we spell
guess “h-y-p-o-t-h-e-s-i-s.” Note guess is one syllable and
hy-poth'e-sis is 4 syllables, so we must be 4 times as smart as ordinary people who guess. If you
count letters, we're only twice as smart, so we count syllables. In case you were wondering, that
aside was considered interesting (defined as “anything a college professor personally finds
interesting at the moment,” although students rarely agree that what the professor finds to
be ‘interesting’ really is inherently interesting.
The hypothesis is considered to be an ‘educated’ guess because it is based on previous knowledge (facts and explanations). We, as scientists, understand that previous knowledge refers to previous experimentation, and current library research. Even those of us with grey hair [mine is silver-grey, a trait controlled by genetics just like adult hair color] recognize that ‘library’ can include the web, so long as the websites are reliable. The safest criterion for reliability is the website owner’s imposition of editorial control of content. Sorry to say, but ‘Wikipedia’ is mostly written by High School students, with no editorial oversight. I would like to believe that my PhD in Biology (Ecology) from Unversity of Notre Dame, MA in Botany from Columbia University, New York, NY, and AB in Botany, Zoology and French from University of Kansas provides greater assurance of expertise than does “working on a H.S. diploma.”
For the most rigorous science, we impose additional requirements on the hypothesis, which can also be called a model; and from Statistics hypothesis is abbreviated Ho:
a. the Ho should predict some observable event. This event should occur if the Ho is True, and not occur if the Ho is False.
b. The Ho can therefore be tested in a controlled experiment. The experiment will consist of an experimental group and a control group, where the experimental is set up so the conditions for hypothesis are met, while the control is set up so the conditions for hypothesis are not met.
the event must occur in the experimental for Ho to be true, AND
the event must not occur in the control for Ho to be true
c. the more times an experiment is repeated – the greater our confidence in the result.
Ethical issues arise any time we consider doing experiments on Humans. Under the idea that we
should not harm the patient, care must be taken so that even unexpected effects will not cause harm.
Not surprisingly, it is somewhat difficult to guess what unexpected effects to look for. The
recommended solution is to test first on non-human subjects, monitoring for any and all side effects,
expected and unexpected. The goal is to identify some animal whose physiology relative to the
proposed treatment is similar to Humans to use as the animal model. Like it or not, this
physiological similarity requires, as an asumption, that evolution does occur!
An “interesting” observation in the 1950's was that aspirin (acetylsalicylic acid) with a “B” (as in Bayer) embossed on them work better than those with “A” (as in Anacin, the friendly folks at Bayer claimed that “A” referred to aspirin, not Anacin [aspirin is, however, a registered trade mark of Anacin]) and that either of which works better than plain aspirin with nothing embossed on them (as in generic). To investigate this phenomenon, a blind test was set up with 4 different pills: aspirin tablets with B embossed on them, aspirin tablets with nothing on them, aspirin-free or placebo tablets with B embossed on them, and aspirin-free or placebo tablets with nothing on them. Both groups receiving the “B” tablets had better results than either group with unmarked tablets, whether or not the tablets contained acetylsalicyclic acid. This was identified as the placebo effect in which patients who believe that they are receiving a new miracle drug report better response to the treatment than do those who believe they are receiving the placebo. Later this effect was used to market even “better” aspirins embossed with an “E” and with a mint-green dye added, and even later multi-colored beads of aspirin in capsules. More importantly, it led to the use of blind testing. Unfortunately, it was observed that the blind approach still produced a bias toward the experimental drug, because the supervising medical personnel knew which was the placebo, and communicated this to the patients via body language. This was confirmed by filming (video tape had not yet been commercialized) the supervising physicians during sessions with the test subjects. The test group were told, with a smile while leaning forward signaling enthusiasm, “I want you to try this new medication which promises much better results;” while the control group were told, straight-faced while leaning back signaling disbelief, “You should try this new pill …it's supposed to work.” As a result, the blind trials were replaced by “double blind trials,” in which the personnel supervising the treatments do not know which group is which. All medications and placebos are unmarked, and in coded bottles. The patient charts show the code number and the patients' reported efficacy. Only the non-medical research staff know which codes are the drug and which are the placebo.
Statistics, at its simplest, provides a means for estimating the level of confidence in a
For time to time, I will make references to statistics, but the good news is that I do not intend to
teach you statistics, nor to require you to do statistics. The science [or mathematics] of
statistics is based on 4 critical assumptions:
a. all data are estimates of actual values
b. the average is a better estimate than are the individual observations
c. variance estimates precision, or repeatability of data, by measuring the spread of the data about the average
d. standard error about grand mean includes actual values at stated probability level, and estimates accuracy, or how close the grand mean estimates the actual value. The standard error about the grand mean measures the spread of the means (averages) about the grand mean (average of the averages). [note; one thing which we can never know in Science (or statistics) is the actual value; we can only estimate (guess) what that value is].
TABLE OF CONTENTS
© 2004-2010 TwoOldGuys
revised: 20 May 2010