The recommended text [Brown, J.E. 2008. Nutrition Now, 5th ed. ©Thompson Learning, Inc.] 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 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 [assuming you failed to forget everything you learned in High School science
courses] 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 can't be expected to remember anything from A & P nor from Chemistry, because you probably have taken neither A & P nor Chemistry!
c. However, you must understand the physiology and biological chemistry of nutrients in order to understand good nutrition habits.
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.”
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;” 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 IM-ing their friends] which the students consider to be interesting).
and two definitions which are not considered to be facetious (more will be introduced in context):
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.
There are a few more definitions needed for this introduction. For the most part, these are terms
which I use in a highly restricted sense, although they have broader meanings which are probably
familiar to you.
a. fact: “anything observable.” To be ‘observable’ means that it 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: I assume that you, the student, are 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, the shadow of the Earth on the Moon during an eclipse is an indirect observation that the Earth is round. You should note also that my definition limits facts to a collection of rather boring bits of information accumulated in your life time.
b. explanation: “an attempt to explain a set of facts.” In this context, sunset is an explanation of the set of facts that over several minutes: the sun was observed above the horizon, then partially obscured by the horizon, then completely obscured by the horizon. Technically, ‘sunset’ implies that the Sun moves around the Earth, which few scientists currently believe!
c. Hypothesis: an “educated guess” at an explanation.” This is discussed at annoying length in § 3.
d. claim: “the assignment of some characteristics, often to a product, or to a dietary regime.” 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 applied to dead skin layers of the epidermis (or to hair shafts) will nourish the dead cells (or protein) 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 keys to determining whether or not the claim is supported by research are [obviously] citation of the research [supported], or more subtly, 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 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 by the definition above.
The hypothesis is considered to be an ‘educated’ guess because it is based on previous knowledge. We, as scientists, understand that previous knowledge refers to previous experimentation, or, at least, 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.
a. the Ho should predict some observable event. This event should occur if the Ho is True, and not occur if the HoFalse.
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 each other, 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 expect (or 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) and that either of which works better than plain aspirin with nothing embossed on them (as in generic). To investigate this phenomenon, a 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-ccolored 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 recorders 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 engagement, “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 conclusion.
From time to time, I will make references to statistics, but the good news is that I do not intend to
teach you statistics, expect you to learn 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: 9 Aug 2010