Dietary ascorbic acid and subsequent change in body weight and waist circumference: associations may depend on genetic predisposition to obesity - a prospective study of three independent cohorts
1 Institute of Preventive Medicine, Bispebjerg and Frederiksberg Hospitals, the Capital Region, Nordre Fasanvej 57, Hovedvejen, entrance 5, ground floor, 2000, Frederiksberg Copenhagen, Denmark
2 The Novo Nordisk Foundation Center for Basic Metabolic Research, Section on Metabolic Genetics, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
3 Copenhagen Prospective Studies on Asthma in Childhood, Health Sciences, University of Copenhagen & Danish Pediatric Asthma Center, Copenhagen University Hospital, Gentofte, Denmark
4 Research Centre for Prevention and Health, Glostrup University Hospital, Glostrup, Denmark
5 Danish Cancer Society Research Center, Copenhagen, Denmark
6 Section of Epidemiology, Department of Public Health, Aarhus University, Aarhus, Denmark
7 Department of Cardiology, Aalborg University Hospital, Aalborg, Denmark
8 The National Institute of Public Health, University of Southern Denmark, Copenhagen, Denmark
9 The Boden Institute of Obesity, Nutrition, Exercise & Eating Disorders, The University of Sydney, Sydney, Australia
Nutrition Journal 2014, 13:43 doi:10.1186/1475-2891-13-43Published: 3 May 2014
Cross-sectional data suggests that a low level of plasma ascorbic acid positively associates with both Body Mass Index (BMI) and Waist Circumference (WC). This leads to questions about a possible relationship between dietary intake of ascorbic acid and subsequent changes in anthropometry, and whether such associations may depend on genetic predisposition to obesity. Hence, we examined whether dietary ascorbic acid, possibly in interaction with the genetic predisposition to a high BMI, WC or waist-hip ratio adjusted for BMI (WHR), associates with subsequent annual changes in weight (∆BW) and waist circumference (∆WC).
A total of 7,569 participants’ from MONICA, the Diet Cancer and Health study and the INTER99 study were included in the study. We combined 50 obesity associated single nucleotide polymorphisms (SNPs) in four genetic scores: a score of all SNPs and a score for each of the traits (BMI, WC and WHR) with which the SNPs associate. Linear regression was used to examine the association between ascorbic acid intake and ΔBW or ΔWC. SNP-score × ascorbic acid interactions were examined by adding product terms to the models.
We found no significant associations between dietary ascorbic acid and ∆BW or ∆WC. Regarding SNP-score × ascorbic acid interactions, each additional risk allele of the 14 WHR associated SNPs associated with a ∆WC of 0.039 cm/year (P = 0.02, 95% CI: 0.005 to 0.073) per 100 mg/day higher ascorbic acid intake. However, the association to ∆WC only remained borderline significant after adjustment for ∆BW.
In general, our study does not support an association between dietary ascorbic acid and ∆BW or ∆WC, but a diet with a high content of ascorbic acid may be weakly associated to higher WC gain among people who are genetically predisposed to a high WHR. However, given the quite limited association any public health relevance is questionable.