Changes in Dietary Fat Intake Alter Plasma Levels of Oxidized Low-Density Lipoprotein and Lipoprotein(a)

Abstract

Objective-To assess the effects of dietary modifications on oxidized low-density lipoprotein (LDL). Methods and Results-Thirty-seven healthy women were fed two diets. Both diets contained a reduced amount of total and saturated fat. In addition, one diet was low in vegetables and the other was high in vegetables, berries, and fruit. The dietary intake of total fat was 70 g per day at baseline and decreased to 56 g (low-fat, low-vegetable diet) and to 59 g (low-fat, high-vegetable diet). The saturated fat intake decreased from 28 g to 20 g and to 19 g, and the amount of polyunsaturated fat intake increased from 11 g to 13 g and to 19 g (baseline; low-fat, low-vegetable; low-fat, high-vegetable; respectively). The amount of oxidized LDL in plasma was determined as the content of oxidized phospholipid per ApoB-100 using a monoclonal antibody EO6 (OxLDL-EO6 See page 392There has been a vast amount of interest in pharmacological agents and antioxidants that decrease LDL oxidation in vitro 7-9 and decrease atherosclerosis in animal models in vivo. 10 The data in humans, primarily with vitamin E, however, have been disappointing, although the reasons for this have been recently discussed. 11 Interest has also been focused on non-pharmacological agents and antioxidants, such as natural foods, and their ability to affect LDL oxidation. 12,13 Data on the effects of whole diets with a high intake of fruit and vegetables on LDL oxidation are limited and conflicting. 14 -16 In the present study, we investigated how alterations in the dietary intakes of fat, vegetables, berries, and fruit affected plasma levels of antioxidants and OxLDL. We performed a crossover dietary intervention with two diets, both low in total dietary fat but one was low in vegetables and the other was high in vegetables, berries, and fruit, to find out whether a high intake of natural antioxidants influences the plasma levels of OxLDL. Methods SubjectsWe interviewed and examined 86 women, among whom 37 healthy volunteers were selected and completed the study. The inclusion criteria were: (1) body mass index (BMI) 20 to 29 kg/m 2 ; (2) blood glucose 3.7 to 6.2 mmol/L; (3) plasma cholesterol Ͻ7.0 mmol/L; (4) plasma triglycerides Ͻ3.0 mmol/L; (5) non-smoking; (6) no gastrointestinal, renal, or hepatic diseases or food allergies; (7) no use of vitamins and/or minerals for at least 6 month before the study; (8) not pregnant or lactating. Alcohol intake was assessed by an interview and from the food records. Most subjects were teetotalers and others reported occasional moderate alcohol intake. Six participants used oral contraceptives, and 3 were using postmenopausal estrogen/ progestin supplementation. The average age, height, and weight of the subjects were 43Ϯ12 years, 163Ϯ5 cm, and 63.6Ϯ6.4 kg, respectively. The study was approved by the Ethical Committee of the Faculty of Medicine, University of Oulu and followed the Declaration of Helsinki.

Changes in lipoprotein(a), oxidized phospholipids, and LDL subclasses with a low-fat high-carbohydrate diet

“…Large and medium LDL decreased signifi cantly, whereas small and ous doses of pravastatin and atorvastatin in the MIRACL ( 4 ) and REVERSAL ( 38 ) trials, in children with familial hypercholesterolemia ( 39 ), and in subjects with hypercholesterolemia ( 40 ). Diets low in total and saturated fat have been shown to increase plasma Lp(a) levels ( 25,26,41 ) and there is evidence that this effect may be specifi c for saturated fat ( 41 ). Increases in both Lp(a) and OxPL/apoB with no significant changes in LDL cholesterol or apoB were previously reported in a study of 37 women who consumed diets with reduced fat and high or low vegetable content.…”

The Changing Roles of Dietary Carbohydrates

“…Levels of Lp(a), a lesser studied atherogenic lipoprotein, also increase in a stepwise manner as levels of dietary total and saturated fat are reduced. 21,22 Results from several recent clinical trials are highlighted in Table 1. The reduction in total fat in the recently published Women's Health Initiative would have been expected to elicit Ϸ4.4% reduction in HDL-C and Ϸ12% increase in TG levels.…”

Lipoprotein(a)

“…In a series of studies, Witztum et al have demonstrated convincingly that a key oxidized phospholipid is preferentially associated with Lp(a). [117][118][119] Proinflammatory, oxidized phospholipids are covalently bound to kringle V in apo(a), a portion of apo(a) associated with macrophage IL-8 production. 117 These results suggest that Lp(a) may act as a preferential acceptor that tightly binds oxidized phospholipids transferred from tissues or from other lipoproteins.…”