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Higher intake of the essential fatty acid, linoleic acid (LA), is associated with a decreased risk of developing cardiovascular disease and type 2 diabetes. Supplementation with LA-rich oil can decrease markers of inflammation, improve markers of glycemia and alter body composition. However, it may be difficult to achieve the Adequate Intake (AI) for LA since the LA content of vegetable oils is decreasing and being replaced with oleic acid (OA). One of the metabolic fates of LA is the enzymatic metabolism to oxylipins. A premise of my dissertation is that oxylipins derived from LA may play a beneficial role in the metabolic effects of dietary LA consumption. Additionally, LA is the predominant fatty acid in the phospholipid, cardiolipin, which is important for mitochondria function; the effects of altering LA intake on cardiolipin fatty acid composition in humans warrants investigation. The goal of this research is to explore the impact of increasing LA intake on LA accumulation in the blood, LA-derived metabolites and cardiometabolic markers. The overall hypothesis is daily consumption of ~2 teaspoons of an LA-rich oil will alter fatty acids, LA-oxylipins, cardiolipin species, and adipokines in the blood of adults. The first objective of this research was to assess the effects of LA-rich oil supplementation on adipokines and LA-oxylipins in women with MetS. Sixteen postmenopausal women with MetS consumed 10ml of LA-rich oils, containing 6.9g of LA, each day for 16 weeks in a single arm open-label study. Supplementation with the LA-rich oils increased total and high molecular weight (HMW) adiponectin levels in the plasma as well as 9 LA-oxylipins. Although LA supplementation did not alter body composition, cholesterol levels, blood pressure or markers of inflammation and glycemia at week 16, a larger randomized double-masked placebo-controlled study is needed to further determine the effect of LA supplementation on cardiometabolic markers in adults with MetS. The second objective of this research was to assess if daily consumption of cookies made with an LA-rich oil (LA-cookie) could alter LA levels in the blood and cardiolipin in peripheral blood mononuclear cell (PBMC) in healthy adults. In a double-masked placebo-controlled trial 84 men and women were randomly assigned to consume one LA-cookie per day or one cookie made with OA-rich oil (OA-cookie) per day for two weeks. The LA-cookie increased LA in plasma, erythrocytes and PBMC after 2 weeks of daily consumption. Additionally, the LA-cookie increased the proportion of tetralinoleoyl cardiolipin (4 LA fatty acids side chains; LA4 CL). These results suggest that increasing LA in the diet could affect composition of the inner mitochondrial membrane by altering cardiolipin species. Future studies evaluating if daily consumption of the LA-cookie affect mitochondria function and whether the changes of cardiolipin lead to improved energy metabolism in people are needed. |
