Norman Krinsky; helped redefine diet guidelines across globe
Norman I. Krinsky, a pioneering researcher into the nature of carotenoids, natural pigments that help prevent certain types of cancer and other illnesses, died at Beth Israel Deaconess Medical Center on Nov. 28 due to complications of leukemia. He was 80.
"Carotenoids are the main source of vitamin A in developing countries," said Dr. Robert Russell, of Arlington, former director of the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University School of Medicine and Dr. Krinsky's research partner for 25 years. "They give color to everything you eat, fruits, vegetables, dark green vegetables. They give color to fall leaves. It's carotenoids that make lobsters turn red when you cook them."
Carotenoids also supply the body with antioxidants such as Vitamins A and E, which doctors believe help prevent prostate, lung, and breast cancers, as well as vision ailments such as macular degeneration.
"Norman was the father of carotenoid research," Russell said. "He was one of the earliest people to be interested in these compounds."
Dr. Krinsky held a doctorate in biochemistry, awarded in 1952, and master's and bachelor's of science degrees from the University of Southern California. He was professor emeritus at Tufts University School of Medicine, where he taught for 40 years, and a scientist at the Jean Mayer Center.
He also led a national panel on antioxidants.
Dr. Krinsky began researching carotenoids while studying at Harvard with George Wald, who shared the Nobel Prize for his work detailing the physiology and processes of the eye. Dr. Krinsky went on to examine how carotenoids are metabolized by the body and carried by the bloodstream to individual cells. Next he looked at the variety of mechanisms for breaking down carotenoid compounds into usable antioxidant molecules. Antioxidants are substances that prevent or slow the breakdown of molecules in the body.
But it was the release of a Finnish lung cancer study in the late 1980s that spurred Dr. Krinsky to his first significant discovery, Russell said. Scientists conducting a trial on how carotenoid beta carotene could help prevent lung cancer made a startling discovery: High doses of the compound increased subjects' vulnerability to cancer.
Dr. Krinsky and Russell, a physiologist who had joined the research team, struggled to determine why. They discovered that large doses of beta carotene were broken down into "false vitamin A, which the body mistook for vitamin A," Dr. Russell explained. It was this false vitamin A replacing the actual compound that increased a person's predisposition to cancer.
Dr. Russell called this the "first example of the paradigm, where very high doses produce a paradox."
Dr. Krinsky and Russell and their team's most significant discovery followed. They asked how many molecules of beta carotene are needed to produce one molecule of vitamin A? At the time, conventional wisdom set a ratio of 6:1 beta carotene to vitamin A molecules. They learned that the ratio was actually far higher and varied depending on the food. For example, the ratio of tomato-derived beta carotene to vitamin A molecules is 12:1; and the ratio for spinach is 20:1. In other words, the beta carotene in tomatoes has a greater bioavailability, which characterizes the extent to which a substance is absorbed by a specific tissue.
Shifting the focus onto bioavailability changed public health policies. The National Academy of Sciences adopted their figures; Dr. Krinsky chaired the panel that set the recommended daily allowance of antioxidants for consumption. The World Health Organization also changed its recommendations to align with their discovery.
"Bioavailability is not an issue in our society, where we fortify the milk and bread," Russell said. "We have enough food and enough variety in our diet to get the beta carotene we need.
"It does have huge implications for third world countries," he continued. "Globally, 300,000 children a year go blind due to vitamin A deficiency." This can be addressed, he said, by growing crops with higher bioavailability of vitamin A, such as tomatoes and yellow corn.
Dr. Krinsky was born in Iron River in Michigan's Upper Peninsula and grew up in Chicago.
He and his wife of 48 years, Susan, lived in Brookline for their entire marriage. He was active in the community, volunteering with the American Jewish Committee and Jewish Family & Children's Service, as well as serving on the transition panel for Logan International Airport. Later in life, Dr. Krinsky studied to serve as a docent at the Semitic Museum at Harvard.
"He was a giant," Dr. Russell said. "I've been getting calls and e-mails from all around the world, and I'm not even his family. He's mourned throughout the world."
In addition to his wife, Dr. Krinsky leaves a daughter, Lisa of Arlington; a son, Adam of Bethesda, Md.; and two grandchildren. Services have been held. 