Recommendation 5 Background

  • Wheat
  • Rice
  • Maize (corn)
  • Millet
  • Sorghum
  • Barley
  • Oats
  • Rye
  • Quinoa
  • Amaranth
Cereals or grains are the seeds of cultivated grasses. They contain an average of 70% starch by weight. Unrefined cereals contain dietary fiber, some protein, very little fat, B vitamins, vitamin E, iron, various trace elements (selenium is one) and phytochemicals. Most of these nutrients are concentrated in the germ and husk of the cereal. Both germ and husk are removed during processing. Consumption of refined grains such as white rice, bread and pasta made from white flour, are now generally more common.

Many epidemiological studies have studied dietary fiber intake and the risk of colon cancer. However, the presence or absence of other food substances may be more significant than the presence or absence of dietary fiber. At present there is insufficient evidence that cereals decrease the risk of colon cancer

The AICR/WCRF panel has reached the following conclusion:

Evidence on cereals and cereal foods and the risk of cancer is inconsistent, probably because studies have often not considered degree of refinement of cereals, or the extent to which diets very high in cereals may be deficient in other respects.

The panel notes that diets high in wholegrain cereals possibly decrease the risk of stomach cancer. Diets high in refined cereals possibly increase the risk of esophageal cancer.

Roots & Tubers
  • Beets
  • Carrots
  • Parsnips
  • Radish
  • Rutabagas
  • Turnips
  • Cassava (manioc)
  • Potatoes
  • Sweet potatoes
  • Yams
  • Taro


  • Bananas
  • Green bananas (plantain)
Roots and tubers are underground storage parts of plants. Their starch content varies between 12 and 50%. Plantains are fruits and in some countries they are eaten as vegetables. Generally, they are good sources of fiber, carotenoids, vitamin C, potassium, other vitamins and minerals and other phytochemicals.
  • Beans
  • Peas
  • Lentils
  • Peanuts (groundnuts)
  • Adzuki beans
  • Black beans
  • Black-eyed peas
  • Broad beans (fava beans)
  • Chickpeas (garbanzos)
  • Flageolets
  • Kidney beans
  • Mung beans
  • Pinto beans
  • Soya beans
  • Split peas
  • White beans:
  • Great Northern
  • Canellini
  • Navy
  • Pea Beans
Legumes, also known as pulses, are fruits and seeds of leguminous plants. They are the richest plant sources of protein with a content of 6-11% cooked weight. They are rich in dietary fiber, complex carbohydrates, phosphorus, iron, potassium, B vitamins and phytochemicals. Generally, legumes are excellent sources of folate. They have a trace of fat and no cholesterol. The conclusion by the AICR/WCRF panel in regards to roots, tubers, and plantains is similar to that for legumes:

While there are theoretical reasons to believe that diets high in pulses might protect against some cancers, evidence is currently very limited.

The evidence comes mostly from human epidemiological studies and many of them, not all, were conducted in western populations where legume intake is low and homogenous. Other evidence comes from experiments that show certain phytochemicals from legumes to prevent experimentally induced cancer in animals.

  • Walnuts
  • Hazelnuts (filberts)
  • Almonds
  • Chestnuts
  • Gingko nuts (ginan)
  • Pine nuts (Indian nuts)
  • Pistachios
  • Pecans


  • Brazil nuts
  • Macademia nuts
  • Cashews
  • Sunflower seeds
  • Sesame seeds
  • Pumpkin seeds
  • Poppy seeds
  • Squash seeds
Nuts are the dried fruits of trees. Seeds come from the fruits of plants and contain the embryo and food supply for the next plant. Nuts' and seeds' protein content ranges from 10 to 25% by weight. They are rich sources of unsaturated oils with 70 to 90% of total calories coming from fat. Their fiber content is high, 5-15%, especially if they are eaten with their skins or hulls. Nuts and seeds are rich in vitamins, minerals and phytochemicals, including vitamin E, selenium. There are few studies of nuts and seeds and cancer risk and, therefore, evidence is currently lacking to make a pronouncement.
  • Breadfruit
  • Sago

See Recommendation 5 "How to" for practical applications.


EXTOXNET FAQS Diet and Cancer Homepage

Prepared 1998 by Bernadene Magnuson, Ph.D.
University of Idaho, Dept. of Food Science and Toxicology - EXTOXNET FAQ Team.