A carbohydrate can appear in many forms: sugar, starch, cellulose – and all break down to sugar, once digested. This might sound like a bad thing; however, our bodies need carbohydrates so we can have energy and keep our brains functioning. In fact, 45-65% of our daily calories should be carbohydrates. In general, foods that are predominantly carbohydrate include grains and starches, vegetables and fruit. Dairy is also considered a carbohydrate, but it has more protein and fat than most other carbohydrate rich foods. One gram of carbohydrate provides 4 calories, which is the same as protein and about half the amount of fat.
Not all carbohydrates are created equal. There are simple and complex carbohydrates. Simple carbohydrates break down to sugar more quickly and include whole foods like fruit and milk, as well as processed foods like juice, soda and candy bars. Complex carbohydrates take longer to break down in our bodies and include foods such as rice, whole grain breads and pastas, legumes/beans and some fruits and vegetables. Fiber is also found in many complex carbohydrate foods; it is not readily absorbed, which means it contributes very few to no calories. Insoluble fiber (meaning it does not break down in water) is an important part of our diets because it is good for our digestion and keeps us “regular.” Soluble fiber does break down in water and can help to lower blood sugar and blood cholesterol levels. Some research even suggests that fiber can help prevent weight gain, because it keeps you fuller longer. The Dietary Reference Intake (DRI) for total fiber is 30-38 grams/day for men and 21-25 grams/day for women.
Protein is made up of 21 amino acids. Our bodies have the ability to produce amino acids; however, nine amino acids are considered “essential,” meaning we must get them from the foods we eat. The essential amino acids include methionine, threonine, tryptophan, leucine, isoleucine, lysine, valine, phenylalanine and histidine.
Protein can be found abundantly in our bodies: from enzymes and antibodies to muscles and cartilage. Protein is especially important in our diet during times of stress and growth. In general, we need about 10-20% of daily calories from protein, or about 0.4 grams per pound of body weight. Too much protein can be hard on the kidneys, and any extra calories (even from protein) is turned into fat.
Protein can be found in many different types of foods, from plants, like vegetables and grains, to animal products, like beef, chicken and fish. Vegetarian sources of protein are often leaner (meaning they have less fat) but are often called “incomplete proteins” because they are limited in some amino acids. For instance, beans and legumes lack the essential amino acid methionine, and corn, nuts, rice and grains lack the essential amino acid lysine. When these foods are combined, they create a complete protein. Meat, fish, poultry and soy are considered “complete proteins.”
Although we associate fat on our bodies as a bad thing, fat in our diet is essential and in moderation can be good for us. Every cell of the body incorporates fat and cholesterol in its wall and is determined by the type of fat in our diet. Dietary fat is also necessary to help absorb and transport certain vitamins (those that are fat soluble: A, D, E and K) and antioxidants (such as lycopene, zeaxanthin) into our cells. Dietary guidelines suggest that total fat intake not exceed 30% of calories. With one gram of fat contributing about 9 calories, that can add up quickly. For the average person consuming about 2,000 calories a day, 65 grams of fat/day is appropriate.
Like carbohydrates and protein, not all fat is created equal. Unsaturated fats are liquid at room temperature and should constitute the majority of the fats in our diets; however, most sources of fat have a combination of unsaturated and saturated fat. Monounsaturated fatty acids (MUFA) sources include olive, canola and peanut oils and have been shown to raise HDL (good) cholesterol and lower LDL (bad) cholesterol. Polyunsaturated fatty acids (PUFA) make up other vegetables oils like soybean, safflower, corn and flaxseed. Eating polyunsaturated fats in place of saturated fat can decrease your LDL cholesterol but might also lower your HDL (good) cholesterol. Some PUFAs are essential to our bodies, meaning we must get them from dietary sources. One example is the pro-inflammatory omega 6 fatty acids, found in many seeds and vegetables like soybean oil, corn and safflower and the anti-inflammatory omega 3 fatty acids, found in fish, flaxseed and walnuts. While research has shown that omega-3 fatty acids may improve heart health and help prevent certain cancers, it is important to have a balance of both of these essential fatty acids.
Saturated fat is usually solid at room temperature and comes from animal products like (meat, poultry, whole milk and cheese) and tropical oils (such as coconut and palm oil). These fats should be limited to 10% of total calories because they can negatively impact heart health by increasing LDL (bad) cholesterol. Trans fats are a created by turning a vegetable oil (liquid at room temperature) into a shortening or margarine (solid at room temperature). These are often found in processed foods that contain “partially hydrogenated” oils and should be avoided completely because they can greatly increase the risk of heart disease by lowering the HDL (good) cholesterol and raise the LDL (bad) cholesterol.
Micronutrients are very important in our diets and are found in a variety of foods. They include vitamins and minerals and are essential in for many functions: maintaining the health of the brain, heart, bones, teeth and nerves; making and repairing red blood cells; regulating the body’s balance of fluids; and other vital functions. Vitamins include the fat soluble A, D, E and K, as well as the water soluble B vitamins (thiamine/B1, riboflavin/B2, niacin/B3, pantothenic acid/B5, pyroxidine/B6, cyanocobalamin/B12,) biotin, folic acid and vitamin C. Fat soluble vitamins are best absorbed when consumed with a source of dietary fat and are stored in adipose (fat) tissue, which is why these are considered toxic at high levels. Water soluble vitamins are not stored in the body and need to be consumed daily. Minerals include calcium, iron, magnesium, phosphorus, potassium, sodium and zinc.
Many foods contain a variety of micronutrients, which is why variety is the key to ensuring consumption of all vitamins and minerals. Many fruits and vegetables are particularly good sources of vitamins (especially A, C, E and K, some B vitamins) and many important minerals needed for a healthy body. A wide variety of these healthy foods in your diet will contribute to your overall health and vitality:
- Beta-carotene and related compounds called carotenoids are converted by the body to vitamin A. Carotenoids (from the word “carrot”) are found in high concentrations in carrots and other orange and yellow vegetables and fruits, such as winter squash and cantaloupes. Dark green, leafy vegetables, such as spinach, kale, broccoli, and other members of the cabbage family, also contain high concentrations of carotenoids.
- Dark green vegetables, one of the healthy foods we hear so much about these days, are also excellent sources of folic acid (a B vitamin needed during pregnancy to reduce the risk of birth defects), vitamins E and K, and minerals such as calcium, magnesium, manganese, iron, and potassium. Many fruits are also a good source of minerals in the diet, such as chromium (grapes), iron (cherries), manganese (pineapple), and potassium (apricots, bananas, orange juice, peaches and prunes).
- Citrus fruits are good sources of vitamin C, as is the family of plants that includes tomatoes, red and green peppers, potatoes, and eggplant. Other good sources of vitamin C include papayas, strawberries, kiwis, cantaloupe, and the cabbage family, including broccoli, cauliflower and Brussels sprouts.
One mineral that tends to be overconsumed in America is sodium, an essential mineral and electrolyte that supports many body functions. When consumed in moderation, sodium can be part of a healthy diet. The 2010 Dietary Guidelines for Americans recommend that Americans consume no more than 2,300 milligrams (mg) sodium per day; however, the limit is lower for those who are 51 or older, African Americans of any age, and those who have hypertension, diabetes, or chronic kidney disease. Such individuals should consume no more than 1,500 mg sodium per day. Keep in mind: one teaspoon of salt contains approximately 2,300 mg of sodium. You will find most processed foods (ones that come in a package or a can) are higher in sodium than fresh, whole foods like whole grains, fruits and vegetables.
Hopefully you’ll find this information useful in helping to make better decisions about your daily food intake. Oh, and don’t forget the daily exercise component.