Components of Food

Most of the foods we eat are composed of a mixture of micronutrients (vitamins and minerals) and macronutrients (carbohydrates, fats and proteins). During digestion, the human body converts macronutrients into energy, which is needed for growth, organ function and other body functions.


Carbohydrates are the body’s main energy source and are necessary for organ function (brain, kidney, etc.), intestinal health and physical activity. There are two types of carbohydrates: simple and complex.

Simple carbohydrates

Simple carbohydrates contain sugars, such as lactose and fructose, that are easily broken down by the body and found in foods with both naturally occurring and added sugars. Carbohydrates contain 4 calories per gram.

  • Food source examples: Fruits, fruit juices, milk and non-starchy vegetables

Whole fruits are better than fruit juices because whole fruits also contain fiber, which slows down digestion. Also, processed foods, candy, desserts and sodas are examples of foods with higher amounts of simple carbohydrates and should be limited in your diet.

Complex carbohydrates

Complex carbohydrates take longer to break down into simple sugars and may help stabilize your blood sugar, keep you feeling satisfied after eating and maintain your energy at an even level. Foods with complex carbohydrates also contain dietary fiber (both soluble and insoluble), which aids in digestion and may prevent constipation. In addition, dietary fiber can help you feel full faster and can even reduce your risk for certain types of cancer, particularly colorectal cancer. If you’re like most Americans, you don’t eat enough dietary fiber; however, if you’d like to start eating more, be sure to add it to your diet gradually. If you increase the amount of dietary fiber you consume too quickly, you’ll likely experience gas, cramps and bloating.

  • Food source examples: starchy vegetables, breads and pastas (made with whole grains), brown rice, cereals, beans, lentils, quinoa, amaranth and oats


Myth vs. Fact

Myth: Sugar “feeds” cancer cells.
Fact: Sugar, as a type of carbohydrate, feeds all cells (including cancer cells). However, depriving your cells of sugar will not necessarily slow cancer cell growth. Sugar is more concerning as a cause of weight gain, but in many survivors a small amount of weight gain isn’t typically a problem. You shouldn’t cut sugar out of your diet if there is no medical reason (e.g., diabetes).
         - Margaret Martin, RD, MS, LDN, registered dietitian, PearlPoint Cancer Support



The body uses fats to store energy, transport certain vitamins throughout the bloodstream and cushion the organs. Fats are a great source of calories, especially in times of decreased appetite. Including a bit more fat in your diet – using good fats such as avocado, nuts and olive oil – can help increase your caloric intake. A mix of monounsaturated and polyunsaturated fats – along with a small amount of saturated fats – is the best combination. Fats contain 9 calories per gram, twice as many as carbohydrates and protein.

Monounsaturated and polyunsaturated fats

Monounsaturated and polyunsaturated fats are the best choices for heart health and cholesterol levels.

  • Food source examples (monounsaturated): olive and peanut oils
  • Food source examples (polyunsaturated): canola, sunflower, flaxseed, corn and safflower oils

Saturated and trans fats

Because saturated fats, such as those found in animal fats, processed meats, cheese, and coconut and palm oils, can increase your cholesterol levels and your risk for heart disease, less than 10 percent of your daily calorie intake should come from them. You should also try to avoid trans fats altogether, as they can raise bad cholesterol and lower good cholesterol. Trans fats are primarily found in processed foods, and manufacturers are now required to either remove these fats or label the content on most packaged foods.


Proteins are necessary for growth, immune system health and body tissue repair. If there isn’t enough protein in your diet, your body may start to break down muscle to get the energy it needs. This process isn’t healthy, nor is it efficient; it can slow down the time it takes your body to recover from illness and hinder your body’s ability to resist infection. When your body is fighting cancer and recovering from treatment, it requires even more protein than usual, so be sure to include plenty in your diet. Protein contains 4 calories per gram.

  • Food source examples: poultry, lean red meat, fish, shellfish, eggs, dairy products, beans, peas, lentils, nuts, nut butters and soy



Water makes up about 60 percent of your body weight, and your body needs water to function. While daily fluid needs vary from person to person based on health, activity level and geographic area, the general recommendation is about 10 cups of water per day for men and about 8 cups for women. Some water does come from the foods you eat (e.g., fruits, vegetables, soup, ice cream, etc.) and from other fluids such as coffee and tea, but you still need to drink water to ensure your body cells get the fluid they need. Do your best to consume more fluids, including water, if you are experiencing side effects such as diarrhea or vomiting. These side effects may cause you to lose more fluid, increasing your risk for dehydration. If diarrhea is severe, you may not be able to absorb plain water, so a specialized oral rehydration solution may be recommended. Talk to your doctor or dietitian for more information.



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