Interventions
The intervention was conducted during April–July 2018 at the Human Nutrition Unit (HNU) of ICTAN. Participants consumed 45 g/d of the corresponding oil (OPO or HOSO, and SO during run-in and wash-out, equivalent to 4–5 tablespoons). This amount of oil was calculated considering the nutritional objective established by the Spanish Society for Community Nutrition for the adult population, that recommends that MUFA intake covers 20% of the daily energy intake (equivalent to 44–67 g/d for 2000–3000 kcal/d, respectively) and assuming that no other oils were consumed during the study and that the intake of MUFA-rich foods was restricted (see below). Volunteers were asked to maintain their dietary and lifestyle habits unchanged during the study, replacing their usual cooking oil by the one provided in each phase of the study. They could use the oil for cooking, baking, frying, or raw as salad dressing or on toasts. One litre of the oil corresponding to each phase (OPO, HOSO or SO) was provided to each volunteer per week for family use, thus ensuring no other source of fat was used. Consumption of foods rich in mono- and polyunsaturated fat (olives, sunflower seeds, nuts, avocado, margarine, butter and mayonnaise, except if prepared with the study oils) was restricted.During the study, participants attended the HNU five times. On week 1, before run-in, baseline characteristics of volunteers were recorded, measuring blood pressure and basic anthropometric parameters (height, weight and waist circumference). A fasting blood sample was obtained to measure basal biochemical and haematological parameters. Volunteers handed-in a 72 h detailed food intake record to obtain information on their basal dietary habits. Subsequent visits corresponded to the initial and final time of each 4-week intervention (Fig. 