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Precision Kitchen
A dash of salt? A dollop of cream? At Johns Hopkins ProHealth, such measurements are strictly taboo.

Essie Wilkie, left, scrutinizes each tomato.

For 17 years, a little-known community-based health center has made great contributions to our understanding of diet’s impact on disease prevention.

Johns Hopkins ProHealth, located in Woodlawn and part of the Welch Center for Prevention, Epidemiology and Clinical Research, recruits volunteers to participate in high-impact, national studies that evaluate the effects of diet and lifestyle changes on conditions like diabetes or high blood pressure. The DASH diet, now a cornerstone of hypertension prevention and control efforts, was designed and tested here.

The volunteers are a dedicated crew. For up to six months, they eat only meals specially prepared for the studies. They consume lunch or dinner every weekday under supervision. Plus, they aren’t allowed to gain or lose a pound.

Central to ProHealth’s operation is the metabolic kitchen, where senior dietitian Phyllis McCarron and her team of six work from 7 a.m. to 7 p.m., five days a week cooking, preparing and packaging meals, each with the exact same percentages of nutrients.

There are no smidges or dollops here. To ensure precision, every item in a meal—from an oil to the main ingredient—is carefully measured and weighed using electronic food scales.

Dietition Karen White prepares the color-coded trays.

A current NIH-funded study at two centers, Hopkins and Boston’s Brigham and Women’s Hospital, is comparing the impact of three diets (one high in carbohydrates, one high in protein and one high in “healthy fats” such as olive oil) on heart disease. McCarron and two dietitians at the Boston site devised seven days’ worth of meals and snacks for each of the diets. Each meal was prepared at five calorie levels to meet the calorie needs of the 20 volunteers, who were randomly assigned to the order in which they consumed the diets. All of them consumed each of the diets over three, separate six-week periods.

In the metabolic kitchen, McCarron has narrowed production down to a science. All meals are prepared at least two days in advance. Nonperishables like salt and nuts are measured early and stored in individual plastic containers. Giant rolling carts with shelves are stored in the walk-in refrigerator and freezer, where assembled meals sit on trays color-coded for each diet.

Essie Wilkie prepares fresh fruits and salads, snipping off the ends of bananas or tiny pieces of tomato to equal the weights. Rose Pearson, a cook, portions out the main dishes. Lindsay Tankard measures condiments, nuts and snacks, and slices meat. Ella Greene cooks, organizes and packs the weekend meals. Dietitian Karen White, who is McCarron’s assistant, helps oversee distribution of meals and food safety. Then there’s Millie Laws—the “food police.”

Senior dietition Phyllis McCarron with a perfect portion of carrots.

Laws oversees the dining room, making sure participants eat everything on their tray, no substitutions or exceptions allowed. If a diner drops something as small as a grape to the floor, it’s brought back to the kitchen, weighed, and replaced with another grape of identical mass. But most participants are “extraordinarily compliant,” says ProHealth Medical Director Larry Appel, who is the lead investigator on several studies.

Occasionally, Laws or McCarron have to do some coaxing. For example, a dinner of spaghetti and meatballs comes with a pre-measured packet of parmesan cheese. One participant said she didn’t like parmesan cheese and requested a substitute. She had to eat the parmesan, though, to make the study results valid. So they compromised—by dissolving the parmesan cheese in warm water. The participant drank it.

Creating the menus for these studies can take up to a year, McCarron says. She’s given a total amount of calories, fat grams, etc., for the day. From there, she thinks up general ideas for meals. Next, she tests recipes with her staff to get feedback. For the heart disease study, for instance, they tried about 25 macaroni and cheese recipes before finding a keeper. “People are going to be eating this for six weeks, so it has to be pretty palatable,” McCarron says.

For food supply, McCarron starts with the U.S. Food Service, ordering large amounts of meats and produce. She also has a corporate account with Giant supermarkets and a health food store in Clarksville, Md. Any remaining items are picked up as needed from other markets, or ordered online.

With all of these pressures, McCarron says the biggest challenge is actually Mother Nature. Each participant is given one or two emergency meals to keep in their freezers in case they can’t make it in due to a rain or snow storm. When ProHealth lost power in a storm a couple of years ago, the kitchen crew stored all the prepackaged meals in coolers and put candles in the dining room. During last winter’s snowstorm, they had a messenger service deliver meals to participants stuck at home.

Medical director Larry Appel serves it up.

Jeanne Charleston, ProHealth’s director of clinical operations, appreciates the dedication of the staff and volunteers: “The saying is, ‘You are what you eat,’ and these studies are showing it. That’s what makes it so fascinating.”

Another tribute to McCarron’s team came from a recent female study participant. Part of a six-month diet study, she and her husband got so accustomed to not shopping for food or cooking that they were disappointed when the study ended. Says Greene: “She asked if we had any leftover meals she could take home.”

—Karen Blum



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