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by Douglas PageŠ1999

[In the time it takes to add the numbers, world population increases by 12. Sometime next year, on an otherwise ordinary day, the population of Earth will reach 6 billion people. Ten years later it will approach 7 billion. If this rapacious ocean of humanity is ever to be adequately nourished, we can thank one man. Douglas Page profiles nutritional biochemist Vernon R. Young - the man who knows more about protein and amino acid metabolism than anyone else.]

Vernon Young sits at every table. It would be hard to imagine anyone who has had more of an impact on the world's nutritional requirements than this modest scientist from Massachusetts. When the world eats, Vernon Young watches.

Vernon Young was among the first investigators to study protein metabolism in the elderly.

His work also radically altered how pediatric burn patients are nourished.

And, when Americans began avoiding dairy products because high-fat foods had been linked to heart disease and obesity, Vernon Young was there, inciting the federal government to undertake a public-education campaign to change people's eating habits to compensate for the decrease in calcium intake. Calcium promotes healthy bones in adolescence and prevents osteoporosis and fractures in old age.

But this Welsh-born Massachusetts Institute of Technology nutritional biochemistry professor is perhaps best known for discovering the woeful inadequacies in the most recent international estimates on amino acid requirements for adult humans - as stated in the 1985 "Expert Consultation on Energy and Protein Requirements" report of the Joint United Nations Food and Agriculture Organization, World Health Organization and United Nations University. Young, who recently was awarded the first Danone International Prize for Nutrition for his revolutionary research on proteins and amino acids, found in 1990 that daily amino acid requirements in adults, in fact, are two to three times higher than the FAO/WHO/UNU report recommends.

The imprecise numbers that measure world hunger indicate 13 percent - over 780 million people - lack adequate food and nutrition. According to the Alan Shawn Feinstein World Hunger Program at Brown University, one child in six is born underweight and one in three is underweight by age 5. Hundreds of millions of people suffer anemia, goiter, and impaired vision and health from diets too low in iron, iodine, vitamin A and other essential nutrients.

Hunger persists in spite of technically adequate global food supplies. Political obstinacy alone does not explain this ambiguity. The truth is, what we understand about nutrition is shallow.

Breaking Down Proteins

When protein is broken down by digestion, the result is 22 known amino acids, vital to survival. Eight amino acids are essential - that is, they cannot be manufactured by the body. The other 14, non-essential, can be manufactured when the body is properly nourished. Amino acids are the body's armory, its corps of combat engineers who build cells, repair tissue and form antibodies to fight invading bacteria and viruses. Amino acids also compose part of the enzyme and hormonal systems, fabricate RNA and DNA nucleoproteins, carry oxygen throughout the body and participate in muscle activity.

The amino acid lysine, for example, a key but often under-represented constituent of the cereal grains which supply much of the energy and protein in the diets of people in developing nations, insures adequate absorption of calcium, helps form collagen (which makes up bone cartilage and connective tissues), aids in the production of antibodies, hormones and enzymes. A lysine deficiency can result in tiredness, inability to concentrate, irritability, bloodshot eyes, retarded growth, hair loss, anemia and reproductive problems.

The 1985 FAO/WHO/UNU report specifies a mean daily requirement value for lysine of 12 mg/kg/day or 16 mg/g protein. Young's work indicates the mean daily requirement value for lysine in healthy adults to be about 30 mg/kg/day or 50 mg/g protein - 300 percent higher. Young's recommendations have yet to be accepted. He is well-rehearsed in the bureaucratic bunny-hop. Where others may bray at a lack of agency enthusiasm and leadership, Young points with equanimity to their limited resources. "At the moment there are more pressing international micronutrient issues - such as iodine, iron and vitamin A deficiencies. That's where they tend to focus."

Young's career, a 30 year span over the trench of nutritional dogma, has led to ground-breaking studies on the metabolism of minerals, proteins and amino acids, including new, non-invasive methods for studying protein turnover in muscles.

"Vernon Young's research has made signal contributions to an understanding of the physiology of human protein and amino acid metabolism and its nutritional corollaries," says W. Allen Walker, MD, Conrad Professor of Pediatrics and Nutrition, Harvard Medical School. "Through a series of elegant and creative investigations, he has elucidated protein-energy relationships, refined concepts concerning the nutritional significance of specific amino acids, and established that amino acid requirement values in adults accepted for the past 40 years are not valid."

The FAO/WHO/UNU standards were based on nitrogen balance, in which excretion of nitrogen is measured against protein-nitrogen intake - the traditional technique for making quantitative estimates of the rates at which amino acids are incorporated into body proteins and then eliminated from the body.

Young's recommendations, published in what has come to be known as the MIT Requirement Pattern of Indispensable Amino Acids [Am. J. Clin. Nutr. 58, 670-683] are based on a new technique of his own devising, in which subjects are orally or intravenously given a test amino acid labeled with a natural, non-radioactive isotope of carbon-13 - a normal constituent of carbohydrates and proteins that people consume every day. By analyzing breath samples to measure the extent to which C-13 is retained or oxidized, Young has been able to evaluate how much of the test amino acid the body loses for a given level of intake. "The criteria for our recommendations is the minimal level of intake of an amino acid that is sufficient to make up for the loss that we measure," Young says.

While Young's "tracer balance" method has rewritten the study of amino acid metabolism, the MIT Requirement Amino Acid Pattern has yet to be accepted as conclusive. "The proof of the pudding will be in the eating," says Young, "The next step will be to do long-term studies that relate these kinetic recommendations to indices of health - specifically, comparing the diet that we say is adequate versus the diet recommended by FAO/WHO/UNU, while assessing factors such as body protein loss and maintenance of immune function."

Tracer studies have been initiated in Bangalore, India, with professor Anura Kurpad, determine the lysine requirements of people in this regions. "Our hypothesis is that the amino acid needs of well nourished individuals and for the maintenance of adequate nutrition in these populations is the same worldwide," says Young, a member of National Academy of Sciences and the Institute of Medicine. "It's important to establish that the research that we've done at MIT with MIT students is relevant to the nutritional needs of other populations, especially in developing regions. Our amino acid recommendations to date have been based on healthy adults studied in our clinical research center. We need to know whether people of different nutritional backgrounds have different amino acid needs."

The work has major implications for planning future world food supply. "It appears the world is capable of feeding a population of 15 billion (as projected by the middle of the next century)," Young foresees, "although this will take a synergy and cooperation of effort and resources by all nations."

Plant and animal protein differ in their "richness" of certain essential amino acids, which determines their nutritional value. Young's research indicates that wheat protein (a major cereal in global terms) is limiting in its capacity to efficiently meet our requirements for lysine, for example, and that diets that supply more than about two-thirds of the daily protein as wheat are likely to be inadequate. "Some animal protein (milk, for example) or pulse protein (edible ripe, dry seeds of legumes) should constitute part of the diet to be fully adequate and reduce the risk of amino acid deficiency," says Young. "It boils down to the simple question: 'Can we live by bread alone?' From a protein, amino acid, nutritional point of view, the answer is 'no'. It's not sufficient to just grow more wheat. The quality of dietary protein supply is important for adults as well as children. Dogma says dietary protein quality is not important in adult human nutrition. I don't accept that."

The ubiquitous Young has also carried out a large series of studies on the protein nutritional value of well-processed soy proteins. "We found that this protein source is of high value, approaching that of good quality animal protein, such as egg or meat," he says. This work, adopted by the U.S. Food and Drug Administration, led eventually to a new method for assessing or predicting nutritional value of food proteins.

As is suggested by his work with pediatric burn patients, Young is interested not just in normal protein nutrition, but with the nutritional consequences of severe catabolic conditions. His work, and that of others, at the Shiners Burn Institute and Massachusetts General Hospital, Boston, has contributed significant advances in the way pediatric burn victims are nourished.

"There couldn't be a worse stress than a major 80 percent body burn, yet until relatively few years ago nourishment of burn patients was based on a glucose drip. We're improving upon the nutritional support of these very ill patients," he says with characteristic humility. His findings, for instance, suggest that the amino acid arginine, which is known to improve response to bacteria, promotes healing and is considered crucial for tissue repair in healthy persons, is indispensable for maintaining body protein homeostasis and nutrition in the severely burned pediatric patient.

Nutrition's Tent Pole

Although publicly the unassuming Young remains one of the world's most famous unknown scientists, the father of five stands like a tent-pole in the field of nutrition. He has published over 490 papers, advised over 40 graduate students, and his pivotal work has attracted most of the major awards available to nutritional chemists, including the Mead-Johnson Award (1973), the Borden Award (1983), the McCollum Award (1987), the Rank Prize in Nutrition (1989) and the prestigious Danone Prize, presented last November. Modeled after the Nobel Prize, the global Danone Prize is awarded every two years for work which contributes to understanding and improving human nutrition and public health. Over 500 researchers from 46 countries were candidates. Vernon Young, the only son of a sea captain and a devoted housewife in Rhyl, Wales, is the first recipient.

The world nearly missed its chance at better nutritional health. Having spent much of his youth during the years of World War II at his uncle's farm in the Sherwood Forest area of Nottinghamshire, Young, now 60, began his scientific studies at Reading University, Wales, in animal husbandry, before emigrating to California. In 1960, as an agriculture graduate student in the old Home Economics department at the University of California, Davis, Young gradually became interested in problems as they related to human nutrition. Then, toward the end of his period there, he came across the September, 1964, issue of Scientific American, an edition devoted to food and agriculture, which contained an article written by the famed Nevin Scrimshaw, Institute Professor at MIT, who was to become a life-long mentor, colleague and hero to Young. (In 1991, Scrimshaw was awarded the World Food Prize for his lifelong dedication to alleviating hunger and malnutrition in developing nations.)

"His article on the global problems of protein energy malnutrition really attracted me," says Young. "So I wrote to him and asked if I could work with him. He said 'yes', so we set off on a scientific journey together which has been very exciting."

Upon arriving at MIT, Young was attracted to more than Scrimshaw's science. Young was likewise charmed by Janice, Scrimshaw's secretary, to whom Young has now been married for 32 years. "My wife has been an essential reason for any of my possible successes."

Young, who has a talent for taking his science but not himself too seriously, does not need to have the attention directed toward himself. As a result, other scientists love working with and for him. He impresses colleagues with his unique ability to see both the lumber and the leaves, allowing him to remain focused on the big question without getting distracted by minutia. "He enjoys very much discussing metabolism as it relates to disease state," says Wiley Souba, MD, who serves with Young on research projects at Massachusetts General Hospital and the Shriners Burn Institute. "He is always open to new ideas. Plus, he is very committed to helping young scientists. He has learned to shine in reflected light - the light given off when the young people he supports become successful."

Sadly, fewer students now enjoy Young's sponsorship. He teaches no more courses at the Institute. Not because he doesn't want to, but because MIT's world-class department of Food Science and Nutrition, in which he played a major role with respect to teaching in the graduate program of nutritional biochemistry, was abolished in 1988 due to internal leadership changes.

"My days are now spent being concerned with my research activity, with interacting with my research Fellows and with dealing with national and international committees," he says with no apparent bitterness. Young's lab, where he conducts his human metabolic studies, is attached to a small hospital on campus called the Clinical Research Center. "This is where my Fellows, all of whom are MDs, work," he says.

He is also involved in nearby supporting labs. "My focus is on the integrated nature of human metabolism at the whole-body level. We don't do molecular biology, we do integrated physiology."

What does Young himself eat? Does one of the world's foremost experts in nutrition have a special diet, or suggest what others should eat? "I like most things," says Young, who describes himself as just a decent guy who tries to help the best he can. "I don't think you need to be a martyr. There are different ways of nourishing our bodies in reasonably satisfactory ways. Moderation is the key. It's not a terribly exciting message, but it is the key."

Generating excitement is not Vernon Young's job; that's why we have ice hockey. Vernon Young is making sure we eat right. One day we may appreciate the magnitude of this man's work.

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Suggested Reading

Young, V.R., Scrimshaw, N.S., and Pellet, P.L., "Significance of Dietary Protein Source in World Nutrition: Animal and/or Plant Protein?" in Feeding a World Population of More Than 8 Billion People: A Challenge to Science, edited by J.C. Waterlow, D.G. Armstrong, L. Fowden and R. Riley, 205-212, Oxford University Press, New York (1998).

Young, V.R., Bier, D.M. and Pellett, P.L., "A Theoretical Basis for Increasing Current Estimations of the Amino Acid Requirements in Adult Man, with Experimental Support," American Journal of Clinical Nutrition 50, 80-92 (1989).

Young, V.R., and Steinke, F.H., "Protein and Amino Acid Requirements in Relation to Dietary Food Needs," in New Protein Foods in Human Health, Nutrition, Prevention and Therapy, 9-31, CRC Press, Boca Raton, Florida (1992).

Young, V.R., and Marchini, J.S., "Mechanisms and Nutritional Significance of Metabolic Response to Altered Intakes of Protein and Amino Acids, with Reference to Nutritional Adaptation in Humans,", American Journal of Clinical Nutrition 51, 270-289 (1990).

-end-

This profile appeared in Science Spectra (No. 15, 1999).

 
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