Influence of the Background Diet on Metabolism of Land-based n-3 PUFA

The KoALA study focuses on the impact of variations in the background diet as a confounding factor. The intake of linoleic acid (LA, C18:2 n-6) has been suggested to diminish the metabolism of α-linolenic acid (ALA, C18:3 n-3) to eicosapentaenoic acid (EPA, C20:5 n-3) and docosahexaenoic acid (DHA, 22:6 n-3).

In this context, the proposed study will be conducted to evaluate the influence of the background diet, in particular the impact of the simultaneous intake of LA on the conversion of ALA into their long-chain (LC) metabolites, the incorporation of n-3 LC-PUFA in human tissues and their metabolism into eicosanoids and docosanoids. Further, the influence of a regular intake of milk fat, in particular from free-grazing ruminants, on n-3 PUFA metabolism will be investigated, because short- and middle-chain fatty acids as well as the branched-chain fatty acids in milk fat may influence the conversion of ALA into n-3 LC-PUFA (hypothesis).

Thus, validated nutrition concepts for increasing n-3 LC-PUFA status from plant sources will be developed to ensure an adequate intake of n-3 PUFA according to the guidelines of nutritional societies and as a contribution to the prevention of cardiovascular diseases.

Inclusion criteria

Whether participants meet the inclusion criteria will be evaluated by screening prior the run-in (blood sampling).

• Females (in the menopause) and males (50 % each); age: 40 - 65 years; BMI < 30 kg/m2
• Subjects must be able and willing to give written informed consent, and to comply with study procedures
• Subjects with moderate elevated LDL cholesterol (> 3 mmol/l), without lipid-lowering medication
• Persons who consume a traditional "Western diet" composed of meat, sausage, dairy products, cereals, vegetables, fruits etc.
• Precondition: stable eating habits at least one year before enrollment
• Subjects must have adequate fluency in the German language to complete the questionnaires and understand the daily menu plans
• No antihypertensive medication or stable dose for >3 months prior to start of the study and during the entire study period

Exclusion criteria

• Subjects with any acute or chronic disease (tumor, infection, other), gastrointestinal diseases, diabe-tes mellitus (type I and II), chronic renal disease, diseases of the parathyroids, diseases necessitat-ing regular phlebotomies other chronic diseases which could affect the results of the present study
• Use of medication which could affect the results of the present study including systemic glucocorti-coids, lipid-lowering medication
• Hormone replacement therapy
• Use of dietary supplements, incl. multivitamins, fish oil capsules, minerals, and trace elements (three months before and during the entire study period)
• Weight loss or weight gain (> 3 kg) during the last three months before study begin
• Relevant food allergies (e.g. milk, nuts etc.)
• Pregnancy or lactation
• Transfusion of blood in the last three months before blood sample taking