Ver la versión completa : Six Simple Steps to a Healthy Vegetarian Diet

11-may-2011, 21:42
Vegetarians enjoy significant health advantages, including reduced risk of numerous chronic diseases, and greater longevity. However, becoming vegetarian does not guarantee a healthful diet. There are plenty of vegetarian junk foods – even potato chips and soda pop are generally 100% vegetarian.

Our goal must be optimal health at every stage of the lifecycle, and that is what this lecture is designed to help you accomplish. We will identify the most common errors people make when adopting a vegetarian diet, and provide guidelines to help ensure that these errors are avoided.

Six simple steps to a healthy vegetarian diet include:

1. Reduce refined carbohydrates.
Refined carbohydrates include both simple carbohydrates that are refined, such as white sugar, brown sugar and syrups, and complex carbohydrates (starches) that are refined, such as white flour and white rice products. These foods are nutritional wash-outs, and when they predominate in the diet (as they do for most North Americans), they contribute to obesity, heart disease, type 2 diabetes and gastro-intestinal disorders. Carbohydrates, per say, are not the problem. In fact, the lowest rates of chronic disease in the world are in areas with high carbohydrate intakes. Wherever people do well on high carbohydrate diets, the primary sources of those carbohydrates are whole plant foods such as vegetables, fruits, legumes, grains, nuts and seeds. These foods contain both simple and complex carbohydrates, but they are unrefined. Such foods come packaged with protectors such as fiber, phytochemicals, phytosterols, vitamins, minerals and essential fatty acids. The World Health Organization (WHO) recommends 55-75% of calories come from carbohydrates for maximum disease risk reduction, and not more than 10% of calories from added sugars (average intakes are close to 25% of calories from added sugars).

2. Eliminate trans fatty acids.
Trans fatty acids are unsaturated fats that have been turned from liquid oils to solid fats. In the process, they are changed from flexible, curved molecules to straight rigid molecules. Trans fatty acids are formed primarily in one of two ways - chemically, through the process of hydrogenation, and naturally, in the intestinal tract of ruminant animals such as cows and sheep. From a health perspective, trans fatty acids are a disaster. These fats become incorporated into cell membranes, changing their shape, flexibility and permeability. In so doing, they effectively dumb cells down, impairing their function. Trans fatty acids also competitively inhibit the incorporation of essential fatty acids into cell membranes, keeping out the very fats we desperately need. Gram for gram, trans fats are considered 2 to 4 times more damaging than saturated fats. About 90% of trans fats come from hydrogenated fats in processed and fried foods; the remaining 10% come from meat and dairy products. Our most concentrated sources are margarine, shortening, crackers, cookies, granola bars, baked goods, chips, snack foods and deep-fried foods. The WHO recommends that less than 1% of calories come from trans fatty acids. For a person consuming 2000 kcal per day, that amounts to 2.2 grams, or about half of what you would get in a single donut or medium order of fries.

3. Ensure a reliable source of vitamin B12.
Vitamin B12 is a nutrient that is produced mainly by bacteria. It is present in anything contaminated with B12-producing bacteria. While animal foods are reliable sources of B12, plant foods are not. Although some plant foods may contain traces of B12, they are not consistent, reliable sources. Vegetarians have reduced B12 status relative to omnivores, and vegans have the lowest levels of all groups. Lack of vitamin B12 in the diet causes megaloblastic anemia, nerve damage, gastrointestinal disturbances, and elevated homocysteine. The elevated homocysteine can potentially eliminate any cardioprotective effects of a vegetarian diet. Reliable sources of vitamin B12 for vegetarians include fortified foods (Red Star Vegetarian Support Formula nutritional yeast, cereals, non-dairy beverages, meat analogs, etc.), supplements, and animal products (dairy and eggs) for lacto-ovo vegetarians under 50 years of age. Animal products are not considered a reliable source of vitamin B12 for those over 50 years of age as their ability to cleave B12 from the protein it is bound to can be significantly impaired. To get sufficient vitamin B12 from foods or supplements, we need at least 3 mcg in fortified foods in two or more meals, 10 mcg of supplemental B12 daily or 2000 mcg B12 weekly. Seaweed, fermented foods and organic vegetables are not reliable sources of vitamin B12.

4. Stock up on trace minerals.
There is some evidence that trace mineral absorption can be compromised in phytate and fiber-rich plant-based diets. Trace minerals are essential to optimal health, and it is important that we design our diets to provide sufficient amounts of these nutrients. Iron, zinc and iodine are especially important, though intakes of chromium, selenium, magnesium, manganese and copper can also be lacking. To insure sufficient intakes of most of these nutrients, it is important to eat primarily whole plant foods such as legumes, nuts, seeds, whole grains, vegetables and fruits. Vegetarian consumers should be cautioned against sprinkling foods with wheat bran, which is highly concentrated in phytates that significantly impair mineral absorption. Iodine is found primarily in iodized salt, which many vegetarians avoid. Another significant source of iodine, which may be more acceptable to some people, is kelp powder. We need only about a tenth of a teaspoon per day to provide the 150 mcg RDA.

5. Do not overeat.
Overeating leads to overweight, which in turn increases blood pressure, cholesterol and triglycerides. It also increases risk for heart disease, type 2 diabetes, certain types of cancer, osteoarthritis, gallbladder disease, gout and sleep apnea. It is estimated that being obese effectively ages a person by 20 years. Achieving lifelong healthy weights involves permanent, positive lifestyle changes, including regular physical activity and a healthful diet. One of the most important dietary changes we can make is to moderate our portion sizes. In North America, we supersize almost everything. When people are served large portions, they eat more. We need to be especially conscious of calories from beverages, which can provide 150-500 calories per serving in many cases. Fried foods, fast foods and processed foods are also concentrated in calories, and seem to induce overeating. Finally, we need to ensure a fiber intake of at least 35-50 grams per day. While diet is extremely important, lifelong healthy weights are best achieved when the diet is balanced with an active lifestyle. A balance of cardiovascular, strength and flexibility exercises are recommended for 30-60 minutes per day.

6. Make the foundation of your diet whole plant foods.
Whole plant foods are the most nutrient dense foods in the diet. They contain minimal levels of the most damaging dietary constituents – saturated fat, trans fatty acids, cholesterol, animal protein, pro-oxidants and environmental contaminants. They are also packed with the most powerful protectors in the food supply – fiber, phytochemicals, plant sterols, antioxidants, essential fatty acids and plant protein. The best way to eat these foods is in their whole form. For optimal nutrition aim for 8 or more servings of vegetables and fruits, 2 or more servings of legumes, 5 or more servings of whole grains, and one or more servings of nuts and seeds. Nuts and seeds are very high in energy, so keep portions small – one or two ounces a day is plenty.

For more information about Vegetarian Nutrition, read:
Becoming Vegan (Brenda Davis and Vesanto Melina)
The New Becoming Vegetarian (Vesanto Melina and Brenda Davis)