Effects of Corn and Coconut Oils on Lipoprotein Lipids, Insulin Sensitivity and Inflammation

This is a randomized, crossover, pilot study that includes two screening visits and two 4-week test periods, separated by a 3-week washout. Subjects will consume study products providing 4 tablespoons oil/day of either corn oil or coconut oil replacing the same amount of oil in the background diet. Subjects will otherwise be encouraged to follow their habitual diet during both treatment periods. They will receive diet instructions on the incorporation of food substitutions during the test periods to maintain habitual energy intake. Subjects will record daily study product intake and compliance in a Daily Log. An intravenous glucose tolerance test (IVGTT) will be completed at baseline and the end of each treatment period for evaluation of insulin sensitivity. Fasting blood samples will be collected for lipid profile and high-sensitivity C-reactive protein (hs-CRP) measurements at all visits. Assessments of vital signs and body weight, review of concomitant medication/supplement use and inclusion and exclusion criteria for relevant changes, and evaluation of adverse effects will be performed throughout the study. Compliance will be assessed using the Daily Log intake percentages as the primary source.

Inclusion criteria

• BMI of 18.5-34.9 kg/m2.
• Fasting LDL-C level ≥115 mg/dL and <190 mg/dL, and TG level ≤375 mg/dL.
• Judged to be in general good health on the basis of medical history and screening laboratory tests.

Exclusion criteria

• Atherosclerotic cardiovascular disease including any of the following:

clinical signs of atherosclerosis including peripheral arterial disease, abdominal aortic aneurysm, carotid artery disease [symptomatic (e.g., myocardial infarction, angina, transient ischemic attack or stroke of carotid origin) or >50% stenosis on angiography or ultrasound] or other forms of clinical atherosclerotic disease (e.g., renal artery disease).

• History or presence of clinically important pulmonary (including uncontrolled asthma), endocrine (including type 1 or 2 diabetes mellitus), chronic inflammatory disease (including irritable bowel disease, lupus, rheumatoid arthritis), hepatic, renal, hematologic, immunologic, dermatologic, neurologic, psychiatric, or biliary disorders.
• Known allergy, sensitivity, or intolerance to any ingredients in the study products.
• Uncontrolled hypertension.
• Recent history of cancer, except for non-melanoma skin cancer.
• Recent change in body weight of ± 4.5 kg.
• Recent use of any medications intended to alter the lipid profile [e.g., statins, bile acid sequestrants, cholesterol absorption inhibitor, fibrates, niacin (drug form), omega-3-ethyl ester drugs, or proprotein convertase subtilisin kexin type 9 inhibitors].
• Recent use of any foods or dietary supplement that might alter lipid metabolism [e.g., omega-3 fatty acid supplements (e.g., flaxseed, fish or algal oils) or fortified foods, sterol/stanol products; dietary supplements (including Metamucil® or viscous fiber-containing supplement); red rice yeast supplements; garlic supplements; soy isoflavone supplements; niacin or its analogues at doses >400 mg/d].
• Recent use of weight-loss drugs or programs or antibiotics.
• Recent daily use of non-steroidal anti-inflammatory drugs (except low-dose aspirin) or unstable use of antihypertensive medication.
• Recent use of medications that influence carbohydrate metabolism (e.g., adrenergic receptor blockers, diuretics, hypoglycemic medications, and/or systemic corticosteroids).
• Pregnant, planning to be pregnant during the study period, lactating, or of childbearing potential and unwilling to commit to the use of a medically approved form of contraception throughout the study period.
• Extreme dietary habits (e.g., vegan or very low carbohydrate diet).
• Current or recent history for drug or alcohol abuse.
• History of a diagnosed eating disorder (e.g., anorexia or bulimia nervosa).
• Exposure to any non-registered drug product.