1. ¹Division of Cardiovascular Epidemiology, Institute of Environmental Medicine, Karolinska, Institutet, Stockholm, Sweden
2. ²Department of Food and Nutrition, University of Umeå, Umeå, Sweden
3. ³UCR Uppsala Clinical Research Center, University of Uppsala, Uppsala, Sweden
4. ⁴Unit for Clinical Nutrition Research, Department of Public Health and Caring Sciences, University of Uppsala, Uppsala, Sweden
5. ⁵Department of Cardiology, Karolinska Hospital, Stockholm, Sweden

Correspondence: Dr M Rosell, Karolinska Institutet, Institute of Environmental Medicine, Box 210, Stockholm 171 77, Sweden. E-mail: magdalena.rosell@imm.ki.se

Received 5 September 2003; Revised 4 February 2004; Accepted 29 February 2004; Published online 24 August 2004.

Abstract

OBJECTIVE: This study evaluates the association between abdominal obesity and the intake of dairy fat and calcium using information from dietary data and the relative content of the fatty acids 14:0, 15:0, and 17 : 0 in serum phospholipids (PL) and adipose tissue (AT), which are suggested biological markers for dairy fat intake. This study also explores how the associations were affected when under-reporters (URs) were separated from the analyses.

DESIGN: Cross-sectional study.

SUBJECTS: In all, 301 healthy 63-y-old men with different degrees of fasting-insulin concentrations.

METHODS: Sagittal abdominal obesity (SAD), dietary intake assessed by a 7-day food registration, and the fatty acid composition in serum PL and AT were measured. URs (n=88) and non-under-reporters (non-URs, n=213) were identified by Goldberg's equation, which compares energy intake with energy expenditure, both expressed as multiples of the basal metabolic rate.

RESULTS: The intake of dairy fat, expressed as g/100 g fat, was inversely correlated with SAD; however, this association was only observed in the URs (r=-0.36, P=0.001) and not in the non-URs (r=-0.04, P=0.59). The intake of calcium was inversely correlated with SAD in both groups, although the association was weaker in the non-URs. The intake of dairy fat was related to the relative content of the fatty acids 14:0, 15:0, and 17 : 0 in serum PL and AT (r ranging between 0.32 and 0.55). When these fatty acids were correlated to SAD, inverse associations were seen except for 14:0 in PL (r ranging between -0.17 and -0.29.

CONCLUSION: If there is a true inverse association between the intake of dairy fat and SAD, it remains to explain why this association was not seen in the non-URs. The data gave some indications of an inverse association between SAD and the intake of calcium. The diverse findings observed when the URs and non-URs were separated highlight the question of how to use and interpret dietary data in URs when diet–disease relationships are investigated.