Most adults consume acid-producing diets because their high intake of protein and/or cereal grains in relation to their intake of fruits and vegetables. This study is being done to determine whether acid-base balance can be restored by the addition of dried fruits to the diet. In this study adults with low usual fruit intake will be provided with either 100 g per day of a mix of dried fruits or no dried fruit. Participants will be followed for 1 year. Acid-base status will be assessed by measuring the acid content in 24-hour urine collections.
Most adults consume acid-producing diets because their intake of protein and/or cereal grains is high in relation to their intake of fruits and vegetables. Supplementation with alkaline salts such as potassium bicarbonate and potassium citrate have been shown to reduce 24-hr urinary net acid excretion (NAE) in healthy adults. This approach requires taking many capsules daily, in split doses after each meal with a full glass of water. An alternative and perhaps more acceptable approach to achieving acid-base balance for most adults may be to modify their diet by increasing intake of alkali-producing foods, such as fruit. Maintaining acid base balance may be important for preserving bone and muscle and renal function and other outcomes but this has not been established. The investigators propose to determine whether adults who are provided with 100 g per day of a selection of dried fruits will actually consume enough of it to correct their acid-producing diets, as evidenced by a lowering of their urinary NAE. The investigators will also determine whether and how participants will alter their overall diets or their body weight when provided with the dried fruit. The comparator group will receive no dried fruit (or other intervention).
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
DOUBLE
Enrollment
109
raisins, apricots, figs, and pineapple
Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University
Boston, Massachusetts, United States
change in 24-hour urinary NAE
NAE reflects net acid-base balance
Time frame: 12 month
rate of adherence with dried fruit
weight of dispensed fruit consumed, calculated as weight of fruit dispensed minus the weight of fruit returned
Time frame: 12 months
change in 24-hour urinary N-telopeptide
a measure of bone resorption
Time frame: 12 months
change in fat to lean tissue mass ratio
a measure of change in body composition by dual-energy x-ray absorptiometry (DXA:)
Time frame: 12 months
change in bone mineral density at the total body
measured by DXA
Time frame: 12 months
change in body weight
measured on a standard scale
Time frame: 12 months
change in grip strength
hand grip strength in kilograms assessed by a hand held dynamometer
Time frame: 12 months
Mediterranean diet score
a 14-item scale of adherence to a healthy Mediterranean style diet; a higher score represents a better diet
Time frame: 12 months
change in bone mineral density of the spine
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measured by DXA
Time frame: 12 months
change in bone mineral density of the hip
measured by DXA
Time frame: 12 months
Health Aging and Body Composition-leg strength
defined as ability to do 5 repeated chair stands; assessed on a 4-point scale; a higher score represents a better performance
Time frame: 12 months
Health Aging and Body Composition - standing balance
defined as ability to stand in tandem position measured on a 4-point scale; a higher score represents a better performance
Time frame: 12 months
Health Aging and Body Composition- gait speed
defined as usual gait speed of performing a 6-meter walk; assessed on a 4-point scale; a higher score represents a better performance
Time frame: 12 months
Health Aging and Body Composition-physical performance battery
The total score is 12 points, representing the sum of the 4-point scores of the 3 domains (strength, balance and gait speed). A higher score represents a better performance.
Time frame: 12 months