Today, something will be missing from Ed Clark's diet -- kale.
For nine weeks, Clark and 14 other volunteers at Beltsville Agricultural Research Center shoveled down helpings of the green leaves to help scientists determine why Mom was right when she told you to eat your vegetables.
Kale for breakfast. Kale for lunch. Take-home kale for the weekend.
Today is liberation day. Time for Clark and the others to go back to their regular diets. Time for the scientists at the facility's Human Nutrition Center to gather their data and begin their analysis.
Vegetables improve T-cell counts in the blood and boost the body's immune system so that it is better equipped to resist everything from head colds to cancer, said Beverly Clevidence, who heads the center's Carotenoids Research Unit.
The mystery is why carotenoid-rich vegetables carry such benefits and exactly which vegetables help the most, she said.
"We don't know how it happens or why it happens," Clevidence said. "That's what this study is all about."
Eating kale twice a day hasn't made Clark, 49, jog any faster.
It hasn't made him stronger, smarter or given him any more energy to get through his day as a microbiologist at the Agricultural Research Center's insect biological control laboratory.
So far, the healthy eating has had one side effect.
"It causes a little bit of what you might say is, uh, flatulence," said Clark.
Gas aside, Clark said the $500 stipend and the free meals twice a day made participating worth the hassles.
"It's been kind of enjoyable. I think I'm really going to miss it," he said.
For the first three weeks, participants ate two servings each of kale, sweet potatoes and tomato juice. The doses increased to five servings a day in the second three weeks and to nine servings a day in the final three weeks. A serving is equivalent to about half a cup.
All of the volunteers, found through e-mail notices and advertisements in the Beltsville area, had to bring in samples of their blood, urine and feces once every three weeks for analysis of colonic cells, T-cell counts and other health indicators.
Clevidence said she selected the three specific foods because they represent a cross sample of vegetables and fruits that are rich in cancer-fighting carotenoids.
Tomatoes have lycopene, which is thought to prevent prostate and cervical cancer. Sweet potatoes have beta carotene, believed to cut the risk of lung cancer, and kale has lutein, which prevents age-related blindness, Clevidence said.
As long as the participants downed the required doses, they could eat whatever else they wanted. Thirteen volunteers in a control group were allowed to eat whatever they wanted.
The study, funded by the Army and by a grant from Nestle Foods, was designed with some compassion for the palates of its participants, researchers said.
"Eight or nine servings a day is about as many as we figured they could stand," said Ellen Brown, another Beltsville researcher.
Those on the experimental diet say they found ways to get down their daily doses.
Clark learned to eat his kale with vinegar.
Sue Krofchick, a retired health data analyst from Greenbelt, ate hers with butter and pepper.
Tod Sukontarak, a technician who works with Clark in the insect biocontrol lab, usually mixed his kale with the lunch entree of the day, such as chicken and rice dinner.
Clark said the toughest part of the study was following the order to keep his weight within 5 pounds of what it was when he began the study.
While he is unsure of the diet's health effects, Clark noted that last week he escaped the nagging cold that infected his wife and 2-year-old daughter.
"I don't know if it's the diet or what it is, but I've certainly been exposed, and I haven't gotten it yet," he said.
Clevidence said the diet's health effects will not be be known until March or April, when all the data is evaluated.
Clark says he has nothing special planned for the menu on his first kale-less day.
The study has left him with a sense of the need to eat healthy -- and with a temporary disdain for kale.
"I know I won't be eating kale twice day, that's for sure," he said. "Maybe twice a week, but that's it."
Pub Date: 11/20/96