Hass Avocado Flesh Inhibition of Appearance of Lipid Peroxidation Products When Added to a Ground Beef Patty Consumed by Healthy Volunteers

The Hass Avocado contains monounsaturated fat, lutein, glutathione, vitamin E, and other antioxidants. This study will determine whether avocado exerts a beneficial effect by inhibition of the absorption of malondialdehyde (MDA) which is a measure of lipid peroxidation. In a previous study, we demonstrated that spice antioxidants resulted in a 70 percent decrease in the formation of MDA during cooking and that healthy volunteers consuming burgers made with spice excreted 50 percent less MDA in their urine than subjects consuming a control burger made without spices. Since the spices were added during cooking of the burger, it was not possible to assess the effects of the antioxidants in the stomach. Foods in the stomach continue to form lipid peroxidation products during digestion and this is called the "bioreactor" function of the stomach. In the proposed study known quantities of fresh avocado will be placed on top of a burger prior to consumption to determine whether the avocado inhibits formation of MDA from cooked burger meat in the stomach. Study demonstrated an increase in inflammatory and oxidative markers in mononuclear cells using Western blot analysis of nuclear factor-kappa light chain enhancer of activated B cells (NFkB) and NADPH oxidase subunits following a mixed high calorie meal. Considering the rich content of bioactive compounds in the avocado, we therefore selected these methods for the endpoint determinations as well in this proposed randomized, crossover study.

We will accomplish the following specific aims:

1. To measure plasma and urine malondialdehyde by high performance liquid chromatography before and over6 hours after consumption of the test burgers with or without fresh avocado added just prior to consumption.
2. To measure insulin, glucose, triglycerides, tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6), Interleukin 8 (IL-8), NFkB activation, nitric oxide and peripheral arterial tonometry after each test burger.

These studies will add to the evidence that antioxidants in a lipid phase can inhibit formation and/or absorption of cytotoxic lipid products such as malondialdehyde. Ultimately, a better understanding of the role of bioactive substances from plant foods such as the avocado may demonstrate the importance of plant-based antioxidants in human health.