Docosahexaenoic acid in red blood cells of women of reproductive age is positively associated with oral contraceptive use and physical activity $ Anna R. Magnusardottir a , Laufey Steingrimsdottir b , Holmfridur Thorgeirsdottir b , Geir Gunnlaugsson c , Gudrun V. Skuladottir a,Ã a Department of Physiology, Faculty of Medicine, University of Iceland, Vatnsmyrarvegi 16, IS-101 Reykjavı ´k, Iceland b Public Health Institute of Iceland, Iceland c Center for Child Health Services, Primary Health Care Organisation of Reykjavı ´k Area, Reykjavı ´k, Iceland article info Article history: Received 28 July 2008 Received in revised form 23 October 2008 Accepted 25 October 2008 Keywords: Docosahexaenoic acid Red blood cells Oral contraceptives Physical activity n-6/n-3 Polyunsaturated fatty acid ratio Women of reproductive age abstract Optimal intake of the long-chain n-3 polyunsaturated fatty acid (PUFA) docosahexaenoic acid (DHA) and proper balance between intake of n-6 PUFA and n-3 PUFA are important for human health. Considerable evidence exists to show that DHA has a marked benefit during pregnancy. Lifestyle factors can affect the biosynthesis of DHA from dietary precursors, incorporation into membranes and degradation. The purpose of this study was to investigate the PUFA composition of red blood cells (RBCs) from women (n ¼ 40) in reproductive age, and how it is affected by diet and other lifestyle factors. Of all the lifestyle factors tested oral contraceptive use and physical activity were the ones correlated with DHA in RBCs, after adjustment for DHA intake. The findings indicate that oral contraceptive use and physical activity have a positive impact on the DHA status, as assessed by RBC level, of women in reproductive age. & 2008 Elsevier Ltd. All rights reserved. 1. Introduction The dietary intake ratio of n-6 polyunsaturated fatty acids (PUFA) to n-3 PUFA has increased from 1–2:1 in preagricultural time to 10–20:1 in typical modern Western diet [1,2]. This change is attributed both to an increased intake of n-6 PUFA and to a decreased intake of n-3 PUFA, especially long-chain n-3 PUFA, with 20 or more carbons and 4 or more double bonds [1,2]. Docosahexaenoic acid (DHA, 22:6n-3) is the main membrane long-chain n-3 PUFA in the human body. Marine food and supplements such as cod liver oil are important sources of DHA and other long-chain n-3 PUFA. The human body is capable of biosynthesizing DHA in small amounts from the respective dietary precursors, a-linolenic acid (ALA, 18:3n-3) from plant products and eicosapentaenoic acid (EPA, 20:5n-3) of marine origin [3,4]. Biosynthesis of DHA is higher in women than men, and this has been explained by the action of oestrogen [3,4]. The PUFA composition of red blood cell (RBCs) membrane lipids is a good indicator of dietary PUFA intake over the preceding few months [5]. On the other hand, lifestyle factors such as physical activity can affect the membrane PUFA composition through oxidative stress and compensating increase in antiox- idant activity [6,7]. Improving the long-chain n-3 PUFA status of women of reproductive age could be important in the prevention of several common diseases, such as major [8] and perinatal [9] depression, osteoporosis [10] and breast cancer [11]. DHA is especially important for women planning to become pregnant [12], since the fetus relies on maternal supply and placental delivery of DHA for normal development and function of the central nervous system [13]. The purpose of this study was to investigate the PUFA composition of RBC from women of reproductive age, and how it is affected by diet and other lifestyle factors. 2. Subjects and methods 2.1. Subjects The participants in the present study were 40 healthy, non- pregnant women. They were enrolled at a visit to the Center for Child Health Services in Reykjavı ´k, Iceland, when they came with their 18-month-old children for evaluation of their growth and general development and for vaccination. The National Bioethics ARTICLE IN PRESS Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/plefa Prostaglandins, Leukotrienes and Essential Fatty Acids 0952-3278/$ - see front matter & 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.plefa.2008.10.004 $ Financial support was provided by grants from the Icelandic Research Fund, the Icelandic Research Fund for Graduate Students and the University of Iceland Research Fund. Ã Corresponding author. Tel.: +354 525 4825; fax: +354 525 4886. E-mail address: gudrunvs@hi.is (G.V. Skuladottir). Prostaglandins, Leukotrienes and Essential Fatty Acids ] (]]]]) ]]]–]]] Please cite this article as: A.R. Magnusardottir, et al., Docosahexaenoic acid in red blood cells of women of reproductive age is positively associated with oral..., Prostaglandins Leukotrienes Essent. Fatty Acids (2008), doi:10.1016/j.plefa.2008.10.004