Fundamentals of Nutrition
Protein
Proteins form the body's main structural elements and are found in every cell and all tissue. Your body uses proteins for growth, as well as to build and repair bone, muscles, connective tissue, skin, internal organs and blood. Hormones, antibodies and the enzymes that regulate the body's chemical reactions are all made of protein. Without the right proteins, blood won't clot properly and cuts won't heal. And, if carbohydrates and fat can't meet your energy needs, proteins can be broken down and used as a source of emergency energy.
The average person needs 50–65 grams of protein each day. In addition to meat, poultry and fish, significant amounts of protein are found in beans, milk, eggs, dairy foods, seeds, nuts, grains and soy products. Most Americans get more than enough protein in their diet. As you can see from the list below, it's not hard to fill your daily protein quota: In fact, an average single serving of meat supplies half of your daily requirement!
- Four ounces of lean meat, poultry or fish (about the size of a deck of cards) contain 25 to 35 grams of protein.
- One cup of cooked beans or lentils contains about 18 grams.
- One cup of low fat cottage cheese contains 28 grams.
- Two ounces of solid cheese contain about 16 grams.
- One cup of low fat milk contains 8 grams.
- Two tablespoons of peanut butter contain 8 grams.
- One serving of grain foods (barley, pasta, cereals, whole wheat bread, for example) generally contains 3 to 6 grams of protein.
- One serving of vegetables ranges from 1 to 3 grams.
The Skinny on Carbohydrates: What They Are and Why We Need Them
For too many Americans, carbohydrates—or carbs—have become something to avoid in the daily diet. But as nutrition experts know, carbohydrate is an essential macronutrient that provides fuel for the brain and muscles and contains the fiber needed for proper gut function. Moreover, many foods primarily composed of carbohydrates have been demonstrated through numerous scientific studies to lower the risk for certain cancers, stroke, heart disease and high blood pressure. In addition, these foods play an important role in the control body of weight, especially when combined with exercise. This is why the leading medical and nutrition authorities recommend weight loss programs that are rich in foods containing carbohydrate, such as from whole grains, fruits, vegetables and low-fat dairy products.
What Are Carbohydrates?
Carbohydrates are found in a wide variety of foods and are one of the three major macronutrients (along with fat and protein) that supply the body with energy. But, unlike fat and protein, carbohydrates are efficiently converted into glucose, which is used directly by the muscles and brain. That is why the Institute of Medicine (IOM), part of the National Academy of Sciences, recently issued a recommendation that children and adults get a minimum of 130 grams of carbohydrate per day to maintain maximum brain function. This amount is more than six times more than what the initial phase of the Atkins Diet allows (20 grams of carbohydrate per day).
In addition to being the most easily accessible energy source for muscles and organs of the body, carbohydrates play an important role in the construction and maintenance of the body's tissues, organs and cells, including nerve cells. At the same time, carbohydrates are present in a wide range of foods that bring a variety of other important nutrients to the diet, such as vitamins and minerals, phytochemicals, antioxidants and dietary fiber. A diet high in these nutrients has been associated with a lower risk for certain cancers, cardiovascular disease, stroke and diabetes, among other medical conditions.
Carbohydrates are grouped into two main categories: 1) simple carbohydrates, which contain simple sugars, such as glucose and fructose, found in fruits, berries, some vegetables, table sugar and honey; and 2) complex carbohydrates, found in many plant-based foods, whole grains and low-fat dairy products. For optimal health, nutrition and public health authorities recommend consuming a wide range of carbohydrate-containing foods, with an emphasis on fruits, vegetables, whole grains and low-fat dairy products. For both weight control and good health, experts advise caution in over-consuming processed foods where sugar has been added, such as soft drinks, pastries and other sweets.
How Much Do We Need?
Recognizing the many health benefits associated with carbohydrates—and especially diets rich in fruits, vegetables, whole grains and low-fat dairy foods—the Dietary Reference Intakes Report, issued by the Institute of Medicine in 2002, recommended that Americans get the majority of their calories each day from carbohydrates. Specifically, the IOM report states that:
"Adults should get 45 percent to 65 percent of their calories from carbohydrates, 20 percent to 35 percent from fat, and 10 percent to 25 percent from protein."
The minimum amount of carbohydrate that children and adults need for proper brain function is 130 grams a day.
Added sugars should comprise no more than 25 percent of total calories consumed. The IOM report was designed for normal-weight individuals; overweight people need far less. For adults 50 years and younger, the recommended total intake for dietary fiber is 38 grams for men and 25 grams for women. For those over 50, it is 30 grams and 21 grams respectively.
Understanding Food Labels
In May of 1994, new food labeling regulations went into effect, requiring most packaged foods to provide nutrition information. Prior to these new regulations, food labeling was voluntary and could only be found on about 60 percent of packaged foods. The food labeling regulations were designed to ensure that label information is accurate and reliable and to empower consumers by giving them information to help them choose healthier foods to meet their nutritional needs. The new food label includes a listing of some of the nutrients important to health.
Label Components
The new nutrition label, called "Nutrition Facts," provides information on a variety of nutrients. It also lists the serving size, calories per serving, the percentage of U.S. Recommended Daily Allowance (for people over the age of four) for all the nutrients listed, and the ingredients. Moreover, the new label has bigger type, and the FDA requires that the information appear on a white or other neutral-contrasting background.
The information on the label includes:
- Serving Sizes: These sizes are based on amounts people actually eat and are consistent across product lines. They are not necessarily the same as the serving sizes recommended on the Food Guide Pyramid.
- Calories are listed both as total Calories per serving and amount of Calories from fat per serving. This information is helpful for people who count Calories and monitor their daily intake of Calories from fat, which nutritionists recommend not exceed more than 30 percent of total Calories per day.
- Cholesterol: This figure indicates the amount of cholesterol contained in the food, helpful for people on a cholesterol-lowering diet and for those suffering from atherosclerosis.
- Sodium: This figure indicates the amount of sodium present in the food, useful for people who need to watch their sodium intake, especially those with high blood pressure.
- Percent Daily Value: This figure helps consumers determine if a food is high or low in a nutrient. These percentages are based on an average dietary intake.
- Daily Values: These figures show the recommended minimum amount of some nutrients, such as fiber and carbohydrates, and the maximum recommended amount of other nutrients, such as fat, saturated fat, cholesterol and sodium. Two "Daily Value columns," one for a 2,000-Calorie diet and one for a 2,500-Calorie diet, are shown, because the nutrient needs increase as your Calorie consumption increases.
- Calories per gram of fat, carbohydrate and protein: These figures indicate how many Calories are in one gram of fat, carbohydrate and protein. They can be used to calculate how many Calories of each nutrient are contained in the food (by multiplying the grams of the nutrient times the amount of Calories per gram of nutrient). For example: 45g of carbohydrate times 4 Calories per gram equals 180 Calories from carbohydrate.
Ingredients: The ingredients that make up the product are indicated in descending order by weight; therefore, the first listed ingredient comprises more of the food than any other ingredient.
Health Claims on Labels
Frequently, consumers find claims about a food's nutritional benefits on the packaging. Health claims describe nutritional benefits that a specific food product offers. The government has strict definitions for many health claim terms, including the following:
- Free: A product contains none or only a negligible amount of one or more of these components: fat, saturated fat, cholesterol, sodium, sugar or Calories.
- Reduced: A product has 25 percent less of a nutrient or Calories than the regular product.
- Less: A food contains 25 percent less of a nutrient or Calories than the reference food, whether or not the food has been modified.
- Light: A nutritionally modified product contains one-third fewer calories or half the fat of the referenced product. Term can also refer to the sodium content of a low-fat or low-Calorie food, if it has been reduced by up to 50 percent.
- Low: Used on foods that can be eaten frequently without exceeding the dietary guidelines for fat, saturated fat, cholesterol, sodium or Calories.
- High: Describes a food containing 20 percent or more of the daily value per serving of a specific nutrient.
- More: Food contains 10 percent more of a particular nutrient as compared to the referenced food.
- Healthy: At least 10 percent more of the daily value for one or more of vitamins A and C, iron, calcium, protein or fiber per serving.
Components of a Nutrition Facts panel
Nutrition Facts
Common nutrients, such as total fat, cholesterol, and sodium, are required fields. Other nutrients, such as potassium and Vitamin K, are optional and not required to be listed. Each package must identify the quantities of specified nutrients and food constituents for one serving. It is important to note the following:
1 g of fat = 9 kcal
1 g of protein = 4 kcal
1 g of carbohydrate = 4 kcal
1 g of alcohol = 7 kcal
Serving Size
Serving sizes are standardized to make for easier comparison among similar food items. They are expressed in both common household and metric measures. It is always important to pay attention to a serving size. For instance, a serving of chocolate chip cookies is typically 2 pieces. Hence, if you eat 4 pieces, you will need to double the amount of nutrition content listed on the label.
Calories (kcal)
Calories provide a measure of how much energy you obtain after eating a portion of food. It is always important to find out the total calories. Many consumers are surprised to find that a fat-free product is not necessarily low in calories. Similarly, a sugar-free product is not always low in Calories or low in fat.
Nutrients listed
Total fat, saturated fats; cholesterol, total carbohydrate (including fiber and added sugars), protein, vitamins A and C, calcium and iron are required on the label. Other nutrients are optional and may be listed at the discretion of the manufacturer.
In addition to total calories and total fat, a few other nutrients relevant to heart health are important to pay attention to when reading a label. These include saturated fats, cholesterol and fiber. Effective Jan 2006, all labels should also include trans fatty acids.
Percent Daily Values
Percent Daily Values provide an estimate of the percentage of a nutrient from one serving in a typical 2000 kcal diet.
Daily Reference Values Footnote
This footnote reminds consumers of the daily intake of different foods depending on their own nutritional needs.
Good Fats and Bad Fats
The fact is: we all need fats. Fats help nutrient absorption, nerve transmission, maintaining cell membrane integrity etc. However, when consumed in excess amount, fats contribute to weight gain, heart disease and certain types of cancer. Fats are not created equal. Some fats promote our health positively while some increase our risks of heart disease. The key is to replace bad fats with good fats in our diet.
The Bad Fats: Saturated Fats
Saturated fats raise total blood cholesterol as well as LDL cholesterol (the bad cholesterol). Saturated fats are mainly found in animal products such as meat, dairy, eggs and seafood. Some plant foods are also high in saturated fats such as coconut, palm oil and palm kernel oil.
Trans Fats
Trans fats are invented as scientists began to "hydrogenate" liquid oils so that they can withstand better in food production process and provide a better shelf life. As a result of hydrogenation, trans fatty acids are formed. Trans fatty acids are found in many commercially packaged foods, commercially fried food such as French Fries from some fast food chains, other packaged snacks such as microwave popcorn as well as in vegetable shortening and hard stick margarine.
The Good Fats: Monounsaturated Fats
Monounsaturated fats lower total cholesterol and LDL cholesterol (the bad cholesterol) and increase the HDL cholesterol (the good cholesterol). Nut, canola and olive oils are high in monounsaturated fats.
Polyunsaturated Fats
Polyunsaturated fats also lower total cholesterol and LDL cholesterol. Seafood like salmon and fish oil, as well as corn, soy, safflower and sunflower oils are high in polyunsaturated fats. Omega 3 fatty acids belong to this group.
What can we do?
Avoid using cooking oils that are high in saturated fats and/or trans fats such as coconut oil, palm oil or vegetable shortening. Instead, use oils that are low in saturated fats and high in mono- and polyunsaturated fats such as canola oil, olive oil and flax seed oil.
Minimize using commercially packaged foods, which are high in trans fats. Always read labels to look for trans-fat free alternatives.
As saturated fats are found in animal products, use lower-fat version dairy such as 1% or skim milk instead of homo milk. Trim visible fats and skins from meat products.
