Tomatoes, Olive Oil, and Heart Disease

The Mediterranean Diet has been shown to protect against heart disease, but just why it does so isn't quite clear. Its effects have been credited to a variety of foods in the typical Mediterranean Diet, including components of the fruits and vegetables and the red wine. The effects have also been credited to tomatoes and tomato products, which are an important source of lycopenes (an antioxidant - See The Health of It All: Lycopenes). Similarly, olive oil's monounsaturated fats have often been credited with heart-protective qualities.

Small studies have suggested that cooking tomatoes breaks them down in such a way that the body is better able to absorb the lycopenes (See The Health of It All: Lycopenes and Cholesterol), and other studies seem to indicate that eating tomatoes with the dietary fat contained in olive oil may also influence the levels of lycopene in the body. Researchers in Australia (Nutrition 2006(3);22:259-265) conducted a study specifically to compare the effects of a high-lycopene, low-olive oil diet with a high-lycopene, high-olive oil diet on the levels of lycopene in the body as well as any effects there might be on cholesterol levels.

This was what is known as a "crossover" study, in that there were two initial groups of subjects who each followed one of two meal plans for ten days. For the following 16 days they ate their normal meal plans (a "washout period). Then the two groups switched meal plans, following the other meal plan for an additional ten days. The two meal plans contained the same basic foods and were individualized for each participant to the extent that their meal plans were designed to maintain their current weight. The two plans were different in that their high-lycopene diet (in the form of tomato paste or tomato soup) included low levels of olive oil or high levels of olive oil.

Each participant had his or her blood tested on the initial day of each meal plan and at the end of each meal plan, and their four resulting scores were compared.

At the end of both meal plans, the subjects' blood lycopene levels were the same, as were their total cholesterol and LDL cholesterol (the bad stuff). But those on the high-olive-oil diet had higher HDL cholesterol (the good stuff), their ratio of total cholesterol to HDL cholesterol had improved, and their triglyceride levels had also improved. Because the study was designed that way, the participants' body weights stayed the same, so these results can not be attributed to weight loss.

The other diets (high carb / high-GI and high protein / low-GI) had similar numbers of participants losing weight.

What this means for you:

This is a small study of just 21 people, but it supports what we already know: that lycopenes are good for you, olive oil is good for you, and best of all, they taste good together. So make some pasta sauce!

Tomato Sauce from Canned Tomatoes | Tomato Sauce from Fresh Tomatoes
Low Acid Tomato Sauce for Those with GERD / Acid Reflux

First posted: July 28, 2006