According to the 2010 Dietary Guidelines, we should get most of our nutrients from our diet. Whole, nutrient-dense foods (rich in nutrients with few calories) should be preferred over processed foods, which are usually energy-dense (lots of calories per weight) and nutrient-poor.
Food sources are divided into six major groups:
- Grains
Grains are cereals such as rice, wheat, rye, corn, barley and oats. A whole grain is composed of endosperm, germ, and bran, and is a good source of carbohydrates (sugar, starches and fiber), vitamins and minerals. However, when a grain is refined, the germ and the bran are removed to improve texture and taste, and several nutrients (such as fiber, iron and B vitamins) are lost in the process. Brown rice, bulgur, oatmeal, and whole-wheat flour are examples of whole grains, while white flour, white rice, and degermed cornmeal are examples of refined. Even though many refined grain products are enriched with vitamins and minerals, the consumption of whole grains is vital because they provide dietary fiber.
- Vegetables
Vegetables are edible plant parts such as leaves, stems, and roots. They are great sources of carbohydrates (starches and fiber), vitamins, minerals, and phytochemicals. Vegetables usually offer many nutrients with just a few calories. They may be consumed raw, cooked, canned, frozen, dried or in juice form. However, for most vegetables, gentle cooking methods are advised in order to preserve vitamin content.
There are many types of vegetables available: dark green such as broccoli, kale and spinach; red and orange such as carrots, sweet potatoes and red peppers; and starchy, such as potatoes, corn and green peas. Some vegetables don’t fall into any of the previous categories – onions, artichokes, cauliflower and zucchini are a few examples. There are also beans and peas such as black beans, lentils, chickpeas and soy beans. These are unique vegetables, because they are also an excellent source of protein.
- Fruits
Fruits are also an edible part of plants; they differ from vegetables in that they are usually sweet[1]. Fruits provide carbohydrates (sugar and fiber), vitamins, minerals and phytochemicals, and have high water content. They are considered nutrient-dense foods, because they usually offer several nutrients with just a few calories. They may be consumed fresh, cooked, canned, frozen, dry or juiced. Apples, bananas, berries, oranges and peaches are just a few examples.
- Dairy
The dairy group consists of fluid milk and milk products such as cheese and yogurt. Milk is a great source of carbohydrates (sugar), protein, vitamins (such as vitamin D), and minerals (such as calcium). However, whole milk and its products also contain saturated fat. Actually, some milk products (such as butter, heavy cream, and cream cheese) are almost 100% fat! To avoid overconsumption of saturated fat, the 2010 Dietary Guidelines recommend that you choose fat-free or low-fat varieties.
- Proteins
This group contains a variety of animal and plant foods that are great sources of protein, vitamins and minerals. Animal sources are meat, poultry, eggs, and seafood; these foods also contain saturated fat and cholesterol. Because of that, the consumption of lean cuts of meat is recommended. Beans, nuts, and seeds are plant sources of protein, but they also provide carbohydrates (starches and fiber) and unsaturated fats. Even though nuts are high-fat, energy-dense foods, they are considered heart-healthy foods, because their unsaturated fatty acids may have a positive effect on blood cholesterol[2].
- Oils
Oils are fats that are liquid at room temperature, and even though they provide essential nutrients, they are required only in small amounts in the diet. Oils may be obtained from plant or animal sources. Canola oil, olives and olive oil, avocados, and nuts are examples of plant sources, while fatty fishes such as salmon and tuna are animal sources.
Unfortunately, there is no such thing as the perfect food. In order to get all the nutrients our body needs, it is imperative that we consume a variety of foods from all food groups. Moderation is also warranted in order to maintain the energy equation balance. Remember that consuming more calories than you are able to expend will result in weight gain. So pay attention to serving sizes of foods, and avoid consuming oversized portions.
The American Dietetic Association (ADA) also offers some tips for improving eating habits:
- Make small changes over time.
- Try new foods in order to introduce variety to your diet.
- Balance energy intake with physical activity.
- Don’t eliminate your favorite foods; practice moderation instead.
The USDA recently replaced the food pyramid (my pyramid) for a plate icon (choose my plate) in order to make the nutritional guidelines easier to understand. Below, you will find a sample of the recommendations for moderately active adult women. Complete information can be found at www.chosemyplate.com.
[1] The sweet taste of fruits is attributed to their high content of sugar (fructose).
[2] “Nuts and Your Heart: Eating Nuts for Heart Health.” Available at http://www.mayoclinic.com/health/nuts/HB00085