Calcium as Part of a Normal Protein Diet May Increase Fecal Fat and Energy Excretion

April 8, 2005

March 29, 2005 - Calcium, taken along with a normal protein diet, increases

fecal fat and energy excretion, according to the results of a randomized

crossover study published in the April issue of the International Journal of

Obesity. The investigators suggest that this may help explain weight loss

from high-calcium diets.

" Observational studies have shown an inverse association between dietary

calcium intake and body weight, and a causal relation is likely, " write R.

sen, MD, from the Royal Veterinary and Agricultural University in

Frederiksberg, Denmark, and colleagues. " However, the underlying mechanisms

are not understood. "

Ten subjects each received three isocaloric one-week diets containing low

calcium and normal protein (LC/NP; 500 mg calcium; 15% of energy from

protein), high calcium and normal protein (HC/NP; 1,800 mg of calcium; 15%

of energy from protein), and high calcium and high protein (HC/HP; 1,800 mg

of calcium; 23% of energy from protein).

Although calcium intake did not affect 24-hour energy expenditure or fat

oxidation, fecal fat excretion increased approximately 2.5-fold during the

HC/NP diet compared with the LC/NP and the HC/HP diets (14.2 vs 6.0 and 5.9

g/day; P < .05). The HC/NP diet also increased fecal energy excretion

compared with the LC/NP and the HC/HP diets (1,045 vs 684 and 668 kJ/day; P

< .05). Calcium intake did not affect levels of blood cholesterol, free

fatty acids, triacylglycerol, insulin, leptin, or thyroid hormones.

Study limitations include not testing the effect of calcium on appetite and

energy intake, so it is possible that calcium may also have metabolic

effects resulting in suppression of energy intake. Effects on energy

metabolism also could not be excluded due to the short duration of the

study.

" A short-term increase in dietary calcium intake, together with a normal

protein intake, increased fecal fat and energy excretion by [approximately]

350 kJ/day, " the authors write. This observation may contribute to explain

why a high-calcium diet produces weight loss, and it suggests that an

interaction with dietary protein level may be important. "

The Danish Dairy Board and the Danish Ministry of Food, Agriculture, and

Fisheries supported this study.

Int J Obesity. 2005;29:292-301

Recommended Posts