Effect of low- and high-calcium dairy-based diets on macronutrient oxidation in humans.
OBJECTIVE
Higher calcium and dairy intakes may be associated with lower body weights, but a mechanism in humans has yet to be elucidated. We compared the effects of a dairy-based high-calcium diet and a low-calcium diet on macronutrient oxidation.


METHODS
Subjects (10 men and nine women) consumed a low-dairy (LD, approximately one serving per day, approximately 500 mg Ca(2+)/d) or high-dairy (HD, approximately three to four servings per day, approximately 1400 mg Ca(2+)/d) energy balance diet for 1 week. Each diet condition was performed twice. On the 7th day, subjects were studied in a room calorimeter under one of four study conditions, applied in a randomized crossover design. Within each diet condition, subjects were studied under conditions of energy balance and acute energy deficit. The deficit (-600 kcal/d) was induced only for the 24 hours that subjects resided in the room and was achieved by a combination of caloric restriction and exercise.


RESULTS
Under energy balance conditions, there was no effect of diet treatment on respiratory quotient or 24-hour macronutrient oxidation. Under energy deficit conditions, 24-hour fat oxidation was significantly increased on the HD diet (HD with deficit = 136 +/- 13 g/d, LD with deficit = 106 +/- 7 g/d, p = 0.02).


CONCLUSIONS
Consumption of a dairy-based high-calcium diet increased 24-hour fat oxidation under conditions of acute energy deficit. We hypothesize that these effects are due to an increased fat oxidation during exercise.
Melanson
Edward L
EL
Center for Human Nutrition, University of Colorado Health Sciences Center, Denver, 80262, USA. Ed.melanson@uchsc.edu
Donahoo
William T
WT
Dong
Fran
F
Ida
Therese
T
Zemel
Michael B
MB
D000328:Adult; D001823:Body Composition / Q000187:drug effects / Q000502:physiology; D002136:Calcium, Dietary / Q000008:administration & dosage* / Q000494:pharmacology; D002153:Calorimetry, Indirect; D018592:Cross-Over Studies; D003611:Dairy Products; D004040:Dietary Carbohydrates / Q000008:administration & dosage / Q000378:metabolism*; D004041:Dietary Fats / Q000008:administration & dosage / Q000378:metabolism*; D004044:Dietary Proteins / Q000008:administration & dosage / Q000378:metabolism*; D002149:Energy Intake / Q000502:physiology; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010084:Oxidation-Reduction; D010101:Oxygen Consumption / Q000502:physiology*; D015431:Weight Loss / Q000187:drug effects / Q000502:physiology*
D002136:Calcium, Dietary; D004040:Dietary Carbohydrates; D004041:Dietary Fats; D004044:Dietary Proteins