Effects of Avocado When Added to a Meat Patty on Inflammation in Healthy Men

Avocados are naturally rich in antioxidants, or beneficial compounds, that can help prevent many diseases, like atherosclerosis (hardening of the arteries). When foods that are high in fats are eaten, certain harmful compounds can be absorbed, which can lead to atherosclerosis. One harmful compound is called malondialdehyde, or MDA. This compound can be measured in the blood and the urine after a person eats a high fat meal. Antioxidants found in herbs and spices may lower the absorption of MDA, which could help prevent the development of atherosclerosis.

This study will determine whether the beneficial compounds of avocado can reduce absorption of MDA. This will be tested by asking healthy males to eat a high fat ground beef patty with or without avocado and then measuring the amount of MDA in their blood and urine samples. Blood flow will also be measured. Healthy men have been chosen for this study because eating high fat hamburger patties can easily mimic in them the condition that causes atherosclerosis. Avocados are rich in antioxidants, which have been shown in previous studies to reduce the absorption of harmful compounds, like MDA, that are formed during cooking. The results from this study may help to explain how high fat foods can be harmful to the body and how beneficial antioxidants from herbs and spices can protect the body.

This will be determined from blood and urine samples after the subjects are given two different meals: a) a plain cooked ground beef patty, and b) or avocado with a cooked ground beef patty.

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.

Eligibility Criteria:
Inclusion Criteria:

* 18 - 35 years old males (inclusive)
* Non-smokers
* Must weigh a minimum of 110 pounds
* Willing to maintain normal activity and eating patterns for the duration of the study
* Willing to maintain their normal diet for the duration of the study but avoid dairy, avocado and meat products.

Exclusion Criteria:

* Females
* Abnormal liver function (aspartate aminotransferase (AST) and alanine aminotransferase (ALT) \> 2 x upper limit)
* Currently taking steroidal drugs
* Known HIV positive or AIDS
* Chronic infectious disease
* Cancer treated within the past two years
* Participation in a therapeutic research study within 30 days of baseline
* Consumption of vegetarian diet
* Allergy or sensitivity to dairy products
* Allergic to avocado