All the tools you need, all the material we use, all the tips... and much more!
viernes, 26 de enero de 2018
Becoming a vegetarian
People become vegetarians for many reasons, including health, concerns about animal welfare, a desire to eat in a way that avoids excessive use of environmental resources, religious convictions, or the use of antibiotics and hormones in livestock. Becoming a vegetarian has become more appealing and accessible, thanks to the year-round availability of fresh produce, more vegetarian dining options, and the growing culinary influence of cultures with largely plant-based diets.
Approximately six to eight million adults in the United States eat no meat, fish, or poultry and several million more have eliminated red meat but still eat chicken or fish. About two million have become vegans, forgoing not only animal flesh but also animal-based products such as milk, cheese, eggs, and gelatin.
Traditionally, research into vegetarianism focused mainly on potential nutritional deficiencies, but in recent years, the pendulum has swung the other way, and studies are confirming the health benefits of meat-free eating. Nowadays, plant-based eating is recognized as not only nutritionally sufficient but also as a way to reduce the risk for many chronic illnesses: "appropriately planned vegetarian diets, including total vegetarian or vegan diets, are healthful, nutritionally adequate, and may provide health benefits in the prevention and treatment of certain diseases."
"Appropriately planned" is the operative term. Unless you follow recommended guidelines on nutrition, fat consumption, and weight control, becoming a vegetarian won't necessarily be good for you. A diet of soda, cheese pizza, and candy, after all, is technically "vegetarian." For health, it's important to make sure that you eat a wide variety of fruits, vegetables, and whole grains. It's also vital to replace saturated and trans fats with good fats, such as those found in nuts, olive oil, and canola oil. And always keep in mind that if you eat too many calories, even from nutritious, low-fat, plant-based foods, you'll gain weight. So it's also important to practice portion control, read food labels, and engage in regular physical activity.
You can get many of the health benefits of being vegetarian without going all the way. For example, a Mediterranean eating pattern — known to be associated with longer life and reduced risk of several chronic illnesses — features an emphasis on plant foods with a sparing use of meat. Even if you don't want to become a complete vegetarian, you can steer your diet in that direction with a few simple substitutions, such as plant-based sources of protein — beans or tofu, for example — or fish instead of meat a couple of times a week.
Only you can decide whether a vegetarian diet is right for you. If better health is your goal, here are some things to consider.
Varieties of vegetarians
Strictly speaking, vegetarians are people who don't eat meat, poultry, or seafood. But people with many different dietary patterns call themselves vegetarians, including the following:
Vegans (total vegetarians): Do not eat meat, poultry, fish, or any products derived from animals, including eggs, dairy products, and gelatin.
Lacto-ovo vegetarians: Do not eat meat, poultry, or fish, but do eat eggs and dairy products.
Lacto vegetarians: Eat no meat, poultry, fish, or eggs, but do consume dairy products.
Ovo vegetarians: Eat no meat, poultry, fish, or dairy products, but do eat eggs.
Partial vegetarians: Avoid meat but may eat fish (pesco-vegetarian, pescatarian) or poultry (pollo-vegetarian).
Can becoming a vegetarian protect you against major diseases?
Maybe. Compared with meat eaters, vegetarians tend to consume less saturated fat and cholesterol and more vitamins C and E, dietary fiber, folic acid, potassium, magnesium, and phytochemicals (plant chemicals), such as carotenoids and flavonoids. As a result, they're likely to have lower total and LDL (bad) cholesterol, lower blood pressure, and lower body mass index (BMI), all of which are associated with longevity and a reduced risk for many chronic diseases.
There's some evidence that vegetarians have a lower risk for cardiac events (such as a heart attack) and death from cardiac causes. In a study involving 65,000 people in the Oxford cohort of the European Prospective Investigation into Cancer and Nutrition (EPIC-Oxford), researchers found a 19% lower risk of death from heart disease among vegetarians. However, there were few deaths in either group, so the observed differences may have been due to chance.
For heart protection, it's best to choose high-fiber whole grains and legumes, which are digested slowly and have a low glycemic index — that is, they help keep blood sugar levels steady. Soluble fiber also helps reduce cholesterol levels. Refined carbohydrates and starches like potatoes, white rice, and white-flour products cause a rapid rise in blood sugar, which increases the risk of heart attack and diabetes (a risk factor for heart disease).
Nuts are also heart-protective. They have a low glycemic index and contain many antioxidants, vegetable protein, fiber, minerals, and healthy fatty acids. The downside: nuts pack a lot of calories, so restrict your daily intake to a small handful (about an ounce). The upside: because of their fat content, even a small amount of nuts can satisfy the appetite.
Walnuts, in particular, are a rich source of omega-3 fatty acids, which have many health benefits. Even so, fish are the best source of omega-3s, and it's not clear whether plant-derived omega-3s are an adequate substitute for fish in the diet. One study suggests that omega-3s from walnuts and fish both work to lower heart disease risk, but by different routes. Walnut omega-3s (alpha-linolenic acid, or ALA) help reduce total cholesterol and LDL (bad) cholesterol, while omega-3s from fish (eicosapentaenoic acid, or EPA, and docosahexaenoic acid, or DHA) lower triglycerides and raise HDL (good) cholesterol levels.
If you stop eating red meat (whether or not you become a vegetarian), you'll eliminate a risk factor for colon cancer. It's not clear whether avoiding all animal products reduces the risk further. Vegetarians usually have lower levels of potentially carcinogenic substances in their colons.
What about bone health?
Some women are reluctant to try a vegetarian diet — especially one that doesn't include calcium-rich dairy products — because they're concerned about osteoporosis. Lacto-ovo vegetarians (see "Varieties of vegetarians") consume at least as much calcium as meat-eaters, but vegans typically consume less. In the EPIC-Oxford study, 75% of vegans got less than the recommended daily amount of calcium, and vegans in general had a relatively high rate of fractures. But vegans who consumed at least 525 milligrams of calcium per day were not especially vulnerable to fractures.
Certain vegetables can supply calcium, including bok choy, broccoli, Chinese cabbage, collards, and kale. (Spinach and Swiss chard, which also contain calcium, are not such good choices, because along with the calcium they have oxalates, which make it harder for the body to absorb calcium.) Moreover, the high potassium and magnesium content of fruits and vegetables reduces blood acidity, lowering the urinary excretion of calcium.
Becoming a vegetarian requires planning and knowledge of plant-based nutrition. Here are some resources that can help:
Protein. Research shows that lacto-ovo vegetarians generally get the recommended daily amount of protein, which is easily obtained from dairy products and eggs. (Women need about 0.4 grams of protein per pound of body weight per day. Because the protein in vegetables is somewhat different from animal protein, vegans may need 0.45 grams of protein per pound of body weight per day.) There are many plant sources that can help vegans meet their protein needs, including peas, beans, lentils, chickpeas, seeds, nuts, soy products, and whole grains (for example, wheat, oats, barley, and brown rice). Vegetarians used to be told that they had to combine "complementary" plant proteins (rice with beans, for example) at every meal to get all the amino acids contained in meat protein. Now, health experts say that such rigid planning is unnecessary. According to the American Dietetic Association, eating a wide variety of protein sources every day is sufficient.
Vitamin B12.Vitamin B12 is found only in animal products, but those products include dairy foods and eggs, so most vegetarians get all they need. If you avoid animal products altogether, you should eat foods fortified with vitamin B12 (certain soy and rice beverages and breakfast cereals) or take a vitamin B12 supplement to avoid a deficiency, which can cause neurological problems and pernicious anemia.
Iron. Studies show that in Western countries, vegetarians tend to get the same amount of iron as meat eaters. The absorption of non-heme iron is enhanced by vitamin C and other acids found in fruits and vegetables, but it may be inhibited by the phytic acid in whole grains, beans, lentils, seeds, and nuts.
Zinc. Phytic acid in whole grains, seeds, beans, and legumes also reduces zinc absorption, but vegetarians in Western countries do not appear to be zinc-deficient.
Omega-3 fatty acids. Diets that include no fish or eggs are low in EPA and DHA. Our bodies can convert ALA in plant foods to EPA and DHA, but not very efficiently. Vegans can get DHA from algae supplements, which increase blood levels of DHA as well as EPA (by a process called retroversion). DHA-fortified breakfast bars and soy milk are also available. Official dietary guidelines recommend 1.10 grams per day of ALA for women, but vegetarians who consume little or no EPA and DHA should probably get more than that. Good ALA sources include flaxseed, walnuts, canola oil, and soy.