© Whole Foods magazine

June 2006

Why Foods Alone Are Failing Us

Significant declines found in the nutritional values of vegetables and fruits.

An Interview with Donald R. Davis, Ph.D. – Part 1

By Richard A. Passwater, Ph. D.


Reading newspaper front pages is almost always depressing. Maybe the only way that I can stomach the headlines is to read the paper while having an otherwise pleasant breakfast. On Tuesday February 28, I read the headline to a front-page article “Today’s veggies, fruits less nutritious,” and I thought, “That’s not news.” We all know that. It was documented over a year ago by my longtime associate, Dr. Don Davis of the University of Texas at Austin and his colleagues at the Bio-Communications Research Institute in Wichita, KS. I wondered, “What’s the big deal? Why is it all of a sudden front page news?”

I started reading the article by Lance Gay of the Scripps Howard News Service anyway. The first paragraph reported that the “nutritional content of vegetables and fruits has declined over the past 50 years—in some cases dramatically.”

The second paragraph began with “Donald Davis, a biochemist at the University of Texas in Austin said that of 13 major nutrients in fruits and vegetables tracked by the U.S. Department of Agriculture from 1950 to 1999, six showed noticeable declines.” I thought, “Wow, sometimes it takes a long time for information to get out. Don published that in December 2004.” His recent publications included “Changes in USDA Food Composition Data for 43 Garden Crops, 1950 to 1999,” by Davis, Epp and Riordan, J Am Coll Nutr 2004; 23:669-682 and “Trade-Offs in Agriculture and Nutrition,” by D.R. Davis, Food Technology, March 2005, p. 120.

So I zapped out an e-mail to Don asking why the information is suddenly gaining front-page exposure.

Please let me back up a bit at this point and tell you a little about Dr. Don Davis. I first met Don through Dr. Roger Williams in the mid-1970s. If you have been reading my writings for a while, you know of my admiration for Dr. Williams. He was my mentor in many ways, teaching me a great deal about nutrition and biochemical individuality. I had the opportunity to lecture from the same podium with him and in 1970, our pictures and news of our research appeared on the same page of Chemical and Engineering News. This great man was a true nutrition pioneer, yet he called me a pioneer for my research. That is the greatest professional compliment I ever received.

Dr. Williams was a professor at the University of Texas at Austin, from 1939 to 1986. He founded and directed the Clayton Foundation Biochemical Institute from 1941 to 1963. The Clayton Foundation Biochemical Institute has been renamed the “Biochemical Institute” at the University of Texas at Austin. Dr. Williams discovered the B-vitamin, Pantothenic Acid, and concentrated and named Folic Acid. He wrote 21 books and nearly 300 articles on nutrition and biochemistry. He was elected to the National Academy of Sciences in 1946 and became president of the American Chemical Society in 1957.

Dr. Williams’s books, including Nutrition Against Disease, Biochemical Individuality, The Wonderful World Within You, and The Prevention of Alcoholism, had wide impact. They helped inspire an explosion of nutrition research, and they strongly influenced many nutritional scientists and physicians such as Drs. Linus Pauling, Wayne Jonas (former director, NIH Office of Alternative Medicine), Jonathan Wright, Alan Gaby, Abram Hoffer, Jeffrey Bland, Carl Pfeiffer, Hugh D. Riordan and myself.

As important as his nutritional discoveries were, the atmosphere and direction he gave to his co-researchers and students were equally important. Dr. Lester Reed succeeded Dr. Williams as director of the Clayton Foundation Biochemical Institute. Dr. Reed was the discoverer of alpha-lipoic acid and its role in energy transfer.

Another important scientist who has worked since 1974 at the Clayton Foundation Biochemical Institute is Dr. Donald R. Davis. Dr. Davis has also been the director of the Roger J. Williams Nutrition Institute (1987-90). In addition to his research at the Biochemical Institute at the University of Texas, Austin, Dr. Davis also serves on the editorial boards of the Journal of Applied Nutrition (editor-in-chief 1986-1991) and the Journal of Advancement in Medicine. Also, he formerly served on the editorial board of Journal of International Academy of Preventive Medicine (1983-85). He has published more than 90 technical articles and letters.

Other discoveries at the Clayton Foundation Biochemical Institute included: two of the three forms of vitamin B-6, lipoic acid, avidin, folinic acid (a derivative of folic acid), synthesis of vitamin B-12, and pioneering work on inositol.

My early discussions during the late-1970s and 1980s with Don centered on vitamin safety, especially vitamin A, and the superiority of whole grains over processed grains. Later, I became very interested in Don’s research with the nutrient content of foods and his unique way of presenting the information so that the nutrient value of the food was readily apparent.

Later, Don and his colleague, Dr. E. H. Strickland, developed a computerized program and database called NutriCircles that all nutritional scientists, nutritionists and even the general public could use as an aid to evaluating foods and diets. The key is that the level of each nutrient is shown graphically by bars radiating from the center towards a ring representing the RDA level for that nutrient. A food with high nutrient density is readily apparent by the length of bars in the graph and how bars fill the circle to form a “bull’s eye” look. This gives great visual imaging to an otherwise obscure and nondescript list of numbers. Figure 1 shows the NutriCircles presentation of processed grain compared to whole grain.


Figure 1 compares un-enriched flour (left) to whole wheat (right). Enriching the flour (Figure 2) helps, but that still does not equal whole grain flour (as seen in Figure 2).


Figure 2 depicts enriched flour.


So that’s the background. Now let’s get back to the “new” story. Don’s answer to my e-mail was that he has just presented the 2004 data as part of a talk at the American Association for the Advancement of Science at their annual meeting in St. Louis on February 20, 2006. A large number of the leading science reporters attend this meeting and as a result the information was again brought to the public. However, this time, conditions were right for the news to receive greater prominence. Don included his previous research in his presentation entitled “Trends in the Nutrient and Antioxidant Content of Common Foods.” Following is a conversation Don and I had about the findings and their impact on the nutrition industry.


Passwater: Your earlier interest seemed to be on the physical side—physics and physical chemistry. Why were you interested in this and why did you then become interested in biochemistry and nutrition?

Davis: I loved chemistry and physics in high school and through my postdoctoral education, because they helped me understand how the physical world works. By the time I was an assistant professor of chemistry, at the University of California at Irvine, my interests were moving toward understanding how the biological world works and how people work. My research in physical chemistry began to seem less relevant.

So I was ripe for change about 1970 when one of my general chemistry students came by my office and gave me a copy of Adelle Davis’ book, Let’s Eat Right to Keep Fit. She was a prominent and well-educated nutrition enthusiast and author of that time. I don’t know why my student thought I would be interested, except possibly because I kept a jar of shelled sunflower seeds on my desk as a convenient snack. I was very interested, though as a scientist, I was unsatisfied with the evidence for some of her conclusions. The medical and dietetic professions were quite critical of her. But I was interested in what might be right about her theme that good nutrition is much more important than was commonly supposed for building health and for recovering from illness.

I began reading other nutrition books, too, and soon discovered Roger J. Williams’s Nutrition in a Nutshell and Alcoholism: The Nutritional Approach. Here was a world-class biochemist and vitamin researcher who was equally convinced that improved nutrition had great potential for preventing and overcoming common health problems. To follow my interest, I introduced an elective course for undergraduates, “The Chemistry of Nutrition.” I used Dr. Roger Williams’s newly published Nutrition Against Disease (1971), Dr. Linus Pauling’s Vitamin C and the Common Cold, and, for balance, a dietetics textbook and a book by an anti-”faddist,” The Nuts Among the Berries.


Passwater: What brought you together with Dr. Roger Williams?

Davis: My interest in nutrition grew, and I wrote to Dr. Williams and others, asking if I might spend a sabbatical leave in their laboratories. Only Williams was encouraging (thankfully!), so in late 1973 I spent three months with him in Austin. He was 80 years old, but he still was writing books and articles, and he still had two Ph.D. researchers in his group, as well as younger nutrition colleagues. I did a rat-feeding study of “the average American diet” compared to three others. It produced interesting results, and he invited me to come back, which I did a year later.

Dr. Williams gave me great freedom to follow my interests, and I learned nutrition and biochemistry the way I learn best, in the context of my diverse projects. I absorbed his advanced ideas, and I benefited from not having a background in the narrow view of nutrition as it was taught then. My biochemistry is still weak, but I had stronger numerical skills than most biochemists. Several of my contributions, including my next publication, advance the statistical analysis of nutrition research. About 1980 I found an error in the statistical interpretation of RDAs published by the past chairman of the RDA committee. I was privileged to work closely with Williams through his reluctant retirement in 1986--a remarkable 13 years.


Passwater: Wait a minute. There are two thoughts there that I just can’t let pass without follow-up. What did you find interesting about your rat-feeding study?

Davis: Supplementing the “average American diet” with modest amounts of 25 vitamins and minerals made no obvious differences in the study. The un-supplemented rats seemed to be healthy and to grow well. But the supplement improved the rats’ growth or health in subtle ways, including ways that still may not be considered nutrition-related.

The supplemented rats ate less food, but they grew slightly better. (They were young, male rats.) In skin-patch studies, their hair grew back more quickly, and their wounds healed faster, on average. Later in the study, their average appetite for sugar was found to be much lower. At the end, the supplemented rats recovered much more quickly from a low dose of injected cyanide. There was no vitamin C in the supplement, because rats make their own. Throughout, we saw the biochemical individuality that Dr. Williams frequently emphasized. Some rats’ hair was nearly regrown when others’ hair had hardly begun to regrow. Some rats loved sugar; others didn’t touch it. Details are in the American Journal of Clinical Nutrition, 1976; 29:710-15.


Passwater: What was the statistical error that you found in the interpretation of the RDA concept?


Davis: The chairman of the Committee on Dietary Allowances for the 1974 RDAs later became chairman of the Committee’s parent, the Food and Nutrition Board, for the 1980 RDAs. He often used his status to pooh-pooh any idea that Americans might have poor diets, or benefit from nutritional supplements. One of his arguments in a 1984 article on supplements was that the RDAs were so generous that “about half of the population should require less than half of the RDA.”

I wrote to him that this statement was grossly incompatible with the statistical assumptions in the RDA books (that RDAs are set about two standard deviations above the average need). After nine months he made a small concession: “About 40% of the population should require less than half of the RDA.” I sent him my calculations and graphs showing that only 0% to 1% would have needs that low. After his non-committal reply four months later, I suggested a $500 wager (about $900 today), to be paid to the vindicated party’s favorite, third-party scientific organization. I planned that he would be writing a check to the Linus Pauling Institute. Wouldn’t that be fun for me and truly amazing of him?

Alas, he quickly relented. Close enough, anyway. He wrote that he should have said that about half of the population should need less than 75% of the RDA. (Actual: Half of the population would need less than 77% to 83% of the RDA, according to the published assumptions.)

Thus, I finally corrected one false claim about the RDAs, but I doubt that I made much of a dent in the unrealistic and complacent attitudes about nutrition that prevailed at high levels in those days. This same person suggested about then that it is OK for Americans to get up to 10% of their calories from sugar and other refined foods. In a later public panel in which we both participated, he was clearly completely out of touch with the reality that Americans on average get well over half of their calories from refined foods, and about 20% from refined sugar alone. Unfortunately, these simple facts are still largely unrecognized by those who need to know.


Passwater: And, there are more facts that people need to know. What is the trend in the nutrient value of vegetables and fruits?


Davis: Slowly downward, according to three different kinds of evidence. This downward trend is unfortunate, because vegetables and fruits are important sources of nutrients and phytochemicals that many Americans do not get enough of. In a study of 14 wheats introduced between 1873 and 1995, the average rate of decline in six minerals was 2% to 3% per decade.


Passwater: What brought this to your attention?


Davis: First, a 1997 historical comparison of minerals in fruits and vegetables from the United Kingdom. Then we did our historical comparison of vitamins, minerals and other nutrients in U.S. foods, published in late 2004. Along the way I discovered other kinds of evidence for the downward trend.


Passwater: Let’s pause here for a break and come back next time to look at the different kinds of data you examined that led you to this conclusion. WF

© 2006 Whole Foods Magazine and Richard A. Passwater, Ph.D.

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