Based on centuries-old culinary traditions of the countries situated along the Mediterranean Sea, the Mediterranean diet provides a solid nutritional foundation for vegetarians. Because the Mediterranean diet emphasizes plant-based protein sources, such as whole grains, legumes and nuts, the diet naturally lends itself to a vegetarian eating plan. Following a vegetarian diet within the guidelines of Mediterranean tradition may decrease your risks of heart disease, cancer and Alzheimer’s disease.

In a study published in the "New England Journal of Medicine" in 2003, researchers from Harvard School of Public Health and the University of Athens Medical Center found that residents of Greece who followed the principles of the Mediterranean diet had increased longevity and a lower incidence of heart disease and cancer than study participants who did not adhere to the diet. Researchers concluded that a diet rich in fiber, lean proteins, monounsaturated fats and omega-3 fatty acids, along with moderate amounts of wine with meals, may protect you against chronic disease. A 2006 study published in the “Annals of Neurology” indicates that following a Mediterranean diet may prevent cognitive decline as you age and reduce your risk of Alzheimer’s disease.

Vegetables and fruits, whole grains, legumes, nuts and seeds, olive oil, herbs and spices form the foundation of the Mediterranean diet pyramid. Together, these foods constitute a food group and represent the basis of every meal. Seafood makes up the second food group on the Mediterranean pyramid, followed by poultry, eggs and cheese. Meats and sweets sit at the narrowest point of the pyramid, indicating that they should account for only a small portion of a non-vegetarian diet.

As a vegetarian, you can modify the Mediterranean diet by replacing seafood, poultry and meat with legumes, soy products, nuts and seeds. The Mediterranean diet pyramid and the Mayo Clinic’s vegetarian diet pyramid are similar in their emphasis on grains, legumes and nuts, followed by vegetables and fruits, with fats representing a small segment of your diet. Nuts provide protein, fiber and heart-healthy fats, but are high in calories. Limit your consumption of nuts to one handful per day. Focus on dried beans, tofu or tempeh and non-fat dairy foods to replace the protein in seafood and poultry. To avoid weight gain and excess fat, eat moderate portions of eggs and cheese daily to weekly, as indicated in the Mediterranean pyramid.

Fish oil supplements or fortified foods may replace the omega-3 fatty acids in seafood, which contribute to the cardiovascular benefits of the Mediterranean diet. To replace the vitamin D in fish, use dairy products fortified with vitamin D. Combine bean dishes with generous servings of leafy vegetables and tomatoes -- the vitamin C in the vegetables will increase your absorption of the iron that beans provide.

Take advantage of the Mediterranean diet’s abundant vegetarian options by eating whole-grain breads and pasta, a wide variety of legumes and a colorful array of vitamin-rich fruits and vegetables. Season foods with fresh garlic, basil, oregano and grated Parmesan cheese. Follow the Mediterranean tradition of spending plenty of time outdoors -- sunlight promotes your skin’s production of vitamin D.