Fish and meat intake during pregnancy. The effects on metabolism, bone and body compostition

Abstract

ABSTRACT Fetal programming occurs when nutrients affect the DNA during fetal development and alters the fetus’ genetic make-up. In connection with increasing obesity prevalence focus has been on dietary fats and fatty acids. Two important sources to these nutrients are red meat and fatty fish. The aim of this thesis was to study the effects of fish and meat intake during pregnancy on maternal health and on the offspring’s metabolic health, bones and body composition. Herring or beef was provided to mice (C57Bl/6) during gestation and lactation. Later, after weaning, half of the offspring were crossed over to the other diet and followed to adult age. Weight gain, body composition, insulin sensitivity, tissue fatty acids and plasma triglycerides and cholesterol was investigated. In a sample of the animals bone mineral density, bone mineral content and bone strength was analyzed. It was found that maternal herring diet counteracted adiposity and postweaning herring diet increased insulin sensitivity and reduced plasma triglycerides and cholesterol at an early adult age, but the differences were no longer present when the tests were repeated later in life. The postweaning herring diet also gave a higher n-6/n-3 ratio in the tissues collected at adult age. Maternal beef intake also led to increased bone mineral density and content at an early age, but later the switch to a postweaning herring diet gave better bone strength (in tibia) and mineral density and content. In a longitudinal randomized intervention study in pregnant women, effects of intake of fish and meat and gestational weight gain, fat mass and fat free mass and serum phospholipid fatty acids were investigated. Normal weight women were recruited during the 1st trimester and advised on fish intake (three portions per week), reduced sugar intake (<10 E %), 500 g vegetables and fruits per day and increase energy intake by 350 kcal in the 2nd trimester and by 500 kcal in the 3rd trimester. Meat intake during early pregnancy was associated with fat free mass gain during pregnancy. Serum phospholipid arachidonic acid was associated with meat intake and eicosapentaenoic acid and docosahexaenoic acid was associated with fish intake. The intervention group increased their fish intake. As shown in this thesis, meat and fish intake may affect body composition both in the mother and in the offspring and also bone health in the offspring. Meat and fish intake has beneficial effects on different tissues and health outcomes depending on time of intake. This thesis has added to the knowledge on the effect maternal meat and fish intake may have on maternal body composition and offspring metabolic health, bone health and body composition. Keywords: Fatty fish, red meat, body composition, maternal diet, postweaning diet, metabolism, bone health, herring, beef