For the current study, 13 patients with type 2 diabetes ate either a high-fiber diet (50 grams per day) or the moderate-fiber diet (24 grams per day) recommended by the ADA for six weeks, then switched to the other diet for six weeks. All participants stayed at UT Southwestern's Clinical and Translational Research Center (CTRC) for the final week of each six-week period.
CTRC staff prepared both diets so that they contained the same number and proportion of calories from carbohydrates, fats and proteins, as well as an equal amount of minerals such as calcium, phosphorous, magnesium, sodium and potassium. The high-fiber diet included numerous fiber-rich foods including cantaloupe, grapefruit, papaya, okra, winter and zucchini squash, granola and oatmeal. No supplements were used.
"The reduction of urinary calcium excretion on high-fiber diets tells us that the amount of dietary fiber has a direct impact on calcium absorption," Dr. Garg said. "In other words, the participants excreted less calcium on the high-fiber diet because the additional fiber caused their bodies to absorb less calcium."
Though most of the additional fiber in the high-fiber diet was soluble fiber, Dr. Garg said he cannot say for sure whether soluble or insoluble fiber affects calcium absorption.
"Generally, more fiber of either type is beneficial," he said. "We should encourage people to try food sources rich in fiber and calcium such as spinach, broccoli, figs, papaya, artichoke, okra, beans, mustard and turnip greens, and cactus pads."
|Contact: Kristen Holland Shear|
UT Southwestern Medical Center