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Grains and nutrition - Answers
Activity 2
- What features of grains and pulses may prevent
heart disease
?
- Soluble fibre in oats and barley has been shown to lower blood cholesterol.
- Phytochemicals in grains, such as plant sterols and saponins, have been shown to have a cholesterol-lowering effect.
- Grains contain more polyunsaturated fat than saturated fat, a fatty acid profile shown to lower cholesterol levels.
- Vitamin E, selenium and phytochemicals in grains may prevent the development of atherosclerosis through its antioxidant activities.
- Folate in grains and fortified grain
products may help to lower plasma homocysteine levels, a risk factor
for coronary heart disease. Extract from Grains Research and Development Centre,
Nutrition recommendations, viewed 10.12.2002,
<http://www.gograins.com.au/grainsnutrition/ns/15frame.html>
- What is the function of anti-oxidants
in preventing heart disease?
Antioxidants protect cell membranes from damage by free radicals by acting as scavengers or by slowing down the rate at which free radicals are formed. An imbalance between the formation of free radicals and antioxidant capacity can lead to disease development.
- Why are wholegrains an excellent source of anti-oxidants?
Grains and pulses contain a wide range of anti-oxidants, mainly in the bran layers and the germ.
- What characteristics of grains and pulses may make them useful in weight
management and prevention of heart disease?
- Dietary fibre slows the rate of carbohydrate digestion, reducing the insulin response and increasing appetite satisfaction.
- Grain-based foods and pulses with a low glycaemic index may be more filling and satisfying than foods with a high glycaemic index.
- Grain-based foods and pulses are generally
high in carbohydrate, high in dietary fibre and low in fat, which
means a large amount of these foods can be consumed without consuming
too many calories. Extract from Grains Research and Development Centre, Nutrition
recommendations, viewed 10.12.2002, <http://www.gograins.com.au/grainsnutrition/ns/15frame.html>
- Outline the evidence to suggest that wholegrain-based
foods protect against heart disease .
A study of 34 000 women aged 55-69 years, showed that the risk of dying from heart disease after nine years was reduced by about one-third in women eating as little as one serve a day of wholegrain foods compared to women who rarely ate wholegrain foods.
Nurses' Health Study: lower rates of heart disease after ten years in the women consuming more than two serves of wholegrain foods a day. Most cases of heart disease were reported in those women who almost never ate wholegrain foods. Extract from Grains Research and Development Centre, Nutrition recommendations, viewed 10.12.2002, <http://www.gograins.com.au/grainsnutrition/ns/15frame.html>
Activity 3
- How does dietary fibre prevent cancer?
Dietary fibre prevents cancer by:- forming butyrate after fermentation of dietary fibre and resistant starch which keeps the bowel healthy and has anti-carcinogenic properties
- decreasing the time food is in the intestine and increasing bulk which limits absorption and contact of carcinogens and toxicants with the wall of the gastrointestinal tract
- decreasing the pH of the gut which inhibits
the formation of secondary bile acids which are potentially
carcinogenic. Extract
from Grains Research and Development Centre, Nutrition
recommendations, viewed 10.12.2002,
<http://www.gograins.com.au/grainsnutrition/ns/15frame.html>
- What are the cancer protective properties of anti-oxidants?
Antioxidants:- prevent production of free radicals
- enhance the activity of enzymes
- prevent production of carcinogens
- bind carcinogens and prevent them from attacking the DNA
- enhance immune function.
- What is the evidence to suggest wholegrains are cancer protective?
- Overall, the risk of cancer in those with a high intake of wholegrain foods was 34% lower than those with a low intake of wholegrain foods.
- Nine out of ten studies showed that high intakes of wholegrain foods reduced the risk of colorectal cancer by 21% compared to those with low intakes of wholegrain foods.
- Seven studies showed that high intakes of wholegrain foods significantly reduced the risk of gastric cancer by 43% compared to low intakes of wholegrain foods.
- The risk of seven hormone-related cancers
(breast, prostate, ovarian and endometrial) was reduced by 14%, 10%,
37%, 45% (the last two were statistically significant) in those with
high intakes compared to those with low intakes of whole grain foods. Extract from Grains
Research and Development Centre, Nutrition
recommendations , viewed 10.12.2002
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