Caveat Lector -- Let The Reader Beware!

A new study shows…

How many times have you heard that phrase followed by some new big revelation? It’s usually a new discovery because few scientists want to study and merely confirm what is already known. If they do, the confirmed results often don’t see the light of day. However, if they discover something new then watch out.

More importantly, the media doesn’t grab attention by generating headlines about widely accepted knowledge.  Often times, the new information creates a buzz because it conflicts with previously accepted science; not surprisingly, often these types of studies grab the most headlines. 

The problem with such studies and the headlines they generate is that no single study proves anything—it merely adds to our knowledge. That’s why people are cautioned to not accept any media science headlines at face value without knowing the full scope of the study reported and how its conclusions fit in with the greater body of evidence surrounding the topic.

At a recent wedding, three of my cousins approached me to ask nutritional questions. One even asked me during the meal if what he was eating was healthy.  Another commented that they should watch me to see what I eat to determine what was good for them.  That approach would be a horrible mistake.  A healthy diet should never be judged by one meal alone; healthy food should never be judged on the basis of isolated nutrients.

One would think that it is well understood that a healthy diet should be viewed holistically (in its entirety), but you could be forgiven for thinking otherwise when studies like the one recently published by the CDC hits the media circuit. The study, titled Defining Powerhouse Fruits and Vegetables: A Nutrient Density Approach attempts to clarify the value of consuming certain fruits and vegetables over others based on the levels of certain nutrients they contain.

As part of the study, Jennifer Di Noia, an associate professor of sociology at William Paterson University in Wayne, N.J., crafted a list based on the nutritional density of fruits and vegetables, using data from the U.S. Department of Agriculture. As the basis of determining nutritional value, she used 17 nutrients including potassium, fiber, protein, calcium, iron, thiamin, riboflavin, niacin, folate, zinc, and vitamins A, B₆, B₁₂, C, D, E, and K.

By her own admission, because she felt that since it was not possible “to include phytochemical data in the calculation of nutrient density scores, the scores do not reflect all of the constituents of a fruit and vegetable that may confer health benefits.” By phytochemicals, Dr. Noia is referring to all the antioxidants, like anthocyanins, polyphenols, carotenoids, etc., and other nutrients that naturally occur in fruits and vegetables; the same antioxidants that are believed to work synergistically with all the other nutrients in the fruits and vegetables to deliver the full nutritional value of a food item; the same naturally occurring antioxidants that are believed to play a role in neutralizing free radicals.

In addition, her qualification list only includes 17 nutrients while there are 13 vitamins, 15 minerals, two fatty acids, nine amino acids (she did include proteins, but did not clarify if they were complete proteins that by definition contain all 9 essential amino acids), and water, all of which are considered essential to human functioning. So even though there are 49 absolutely essential (as identified by current science—of course subject to future revision) nutrients, her list was based on only 17. Nevertheless, she concluded that they were apparently the most important.

What were her conclusions? Leafy green vegetables are good.  No big surprise. Raspberries, tangerines, cranberries, garlic, onions, and blueberries are essentially a waste of time when it comes to their nutritional soundness. Why? Because they didn’t have enough of the 17 nutrients she deemed important. Forget about what else they have in them; they just don’t make the cut. That’s just plain absurd.

An essential nutrient is an essential nutrient.  None is more important than another. Further, it’s renders her study meaningless when she leaves out phytochemicals.  If you followed Noia’s logic, you shouldn’t bother eating fruits and vegetables at all. Just pop a pill that includes the same amounts of her 17 key nutrients and call it a “Powerhouse Pill.” Shameless.

Nevertheless, I am very surprised, given the study’s limited utility, that the CDC published it in the CDC’s journal, Preventing Chronic Disease.  More importantly, until I read the actual study, I was baffled by its reported conclusions. Once I knew what criteria had been used, I also knew its true value—zero.  I disdain the use of “powerhouse” to describe any food as being more important than other foods contributing to an overall healthy diet. Using such a word is nothing more than an attempt at hype to grab more media attention. Uch.

For me it invoked once again the saying, Caveat Lector—let the reader beware!