Download 2015-06-26 Food over Nutrients

Preventive Medicine Column
June 26, 2015
Food over Nutrients
The current issue of JAMA features a commentary by two colleagues, calling for an end to what they
term the “ban” on total dietary fat. More specifically, the authors endorse the report of the 2015 Dietary
Guidelines Advisory Committee, in which there is no specific reference to an upper limit for total dietary fat
intake.
The case for abandoning an emphasis on limiting total dietary fat intake is clearly legitimate and
overdue. The world’s healthiest populations vary widely in their total dietary fat intake, but vary far less in
the basic theme of their diets. In all cases, they consume diets of wholesome foods in sensible combinations;
real foods, not too much mostly plants- to borrow from Michael Pollan.
We have long had abundant evidence that reference to total dietary fat was a stark failure to
differentiate baby and bathwater. Some classes of fat, notably manufactured trans fats, are consistently and
uncontestably harmful. Some classes of fat contain specific members that are harmful and others that may be
innocuous; this is where the evidence currently stands for saturated fat. The current enthusiasm for attributing
health benefits to saturated fats may be a product of wishful thinking, reactionary excess, or ulterior motives,
but is not a product of the current weight of scientific evidence. Of note, the Dietary Guidelines Advisory
Committee report, and the new commentary in JAMA, both preserve the recommendation to limit total
saturated fat intake.
Some fats may be beneficial or harmful, depending on total dose and proportion to their counterparts;
this is our current understanding of omega-6 polyunsaturates. Like omega-3 fats, omega-6 fats are essential
nutrients; but we are prone in modern diets to a relative deficiency of the former, and a relative excess of the
latter. Because our intake of omega-3 polyunsaturates tends to be relatively low and these fats are essential
nutrients, more would be better in most cases. Monounsaturated fats, indelibly associated with the
Mediterranean diet, are generally thought to be health promoting.
Our fixation on fat for many years resulted in marked increases in our intake of refined grains and
added sugars. These are both major liabilities of the modern diet, and an obsolete emphasis on limiting total
fat intake may lead inadvertently to ills in this other direction.
Fish, especially fatty fish, are consistently associated with health benefits, and are recommended in
the Dietary Guidelines for Americans. The health benefits of the very-high-fat avocado are widely
recognized. And, in particular, nuts and seeds are consistently and decisively associated with health benefits,
and recommended rather prominently in both the 2010 Dietary Guidelines for Americans, and the 2015
advisory committee report. It does not make a lot of sense to advise limiting intake of nutrients while
advising increased consumption of foods in which those nutrients are found.
For literal decades now, we have fixated on some particular nutrient while looking right past foods,
and overlooking the overall dietary pattern. We have managed to invent an unending variety of junk foods,
each under the halo of some particular nutrient “virtue:” low fat; low carb; low fructose; vitamin fortified;
gluten free. We have invented a parade of ways to eat badly, and are, predictably, mostly fatter and sicker as
a result.
So while the plea in JAMA to lift the “ban” on total dietary fat is valid, the silence on the topic in the
DGAC report may be even more so. The DGAC decided to de-emphasize nutrients altogether, and instead to
emphasize the very items we have been overlooking, foods and dietary patterns: “The overall body of
evidence examined by the 2015 DGAC identifies that a healthy dietary pattern is higher in vegetables, fruits,
whole grains, low- or non-fat dairy, seafood, legumes, and nuts; moderate in alcohol (among adults); lower
in red and processed meats; and low in sugar-sweetened foods and drinks and refined grains.”
When we know that some dietary fats are rather sinister, and others quite salutary, failure to unbundle
the two is obsolete nonsense. When we know we are prone to remove healthful fats from our diets and
replace them with sugar, an emphasis on total fat intake in dietary guidance is obsolete nonsense. A clear
verdict has been rendered in the case of nutritionism, and it is guilty of crimes against humanity.
But let’s be careful. The right response is not to canonize the nutrients we once vilified, but to deemphasize nutrients and emphasize wholesome foods. Recommending for the intake of nuts, but against the
fat content of nuts, was always just plain nutty. Failure to learn from the follies of our nutritional history
would be even more so.
-fin
Dr. David L. Katz; www.davidkatzmd.com; author, Disease Proof; founder, GLiMMER Initiative