Diet through life. Foundation. Learning objectives. To recognise the different key stages in life. To understand why needs for different amounts of energy and nutrients change through life. To describe the energy and nutrient requirements of different life stages to maintain health.
The key stages in life include:
Energy requirements change through life and depend on many factors, such as:
A varied diet, providing adequate amounts of energy and nutrients, is essential before and during pregnancy.
Having a healthy body weight is important. Being underweight can make it more difficult to become pregnant and make it more likely for the baby to have a low birth weight, leading to a greater risk of ill health. Being overweight increases the risk of complications, such as high blood pressure and diabetes during pregnancy.
Folate (the natural form of folic acid found in foods) is needed for rapid cell division and growth in the foetus.
It can reduce the chance of neural tube defects, such as spina bifida, in the baby.
Foods that are good sources of folate are green leafy vegetables, oranges, bread and fortified breakfast cereals.
Women who are trying to become pregnant, or are pregnant, should take a 400 microgram (μg) supplement of folic acid every day until the 12th week of pregnancy.
During pregnancy, a woman’s nutritional needs increase to:
The process of producing breast milk and delivering it to the baby is called lactation.
A mother who is breastfeeding requires extra energy and nutrients. There are also increased demand for nutrients, such as calcium, phosphorous, vitamin A and C.
Breast milk provides all the energy and nutrients a baby needs for growth and maintenance during the first 4 to 6 months of life.
Breast milk provides special proteins, antibodies and white blood cells which help to protect the baby against infection.
It also provides growth factors and hormones, important for the healthy growth and development of the baby.
In the first three days after birth, the mother produces a special form of breast milk called colostrum. It contains less fat, more protein and more protective factors than the breast milk produced later.
After 4 to 6 months of age, milk no longer fulfils all the baby’s need for energy and nutrients. The baby must be given other foods in addition to breast milk or infant formula. This is called weaning.
Foods used during weaning must be semi-fluid and soft since the baby has no teeth and cannot chew.
Cow’s milk should not be given to infants under 1 year of age as the main drink, because it does not provide adequate nutrients for the infant.
The energy requirements of children increase rapidly because they grow quickly and become more active.
Young children do not have large stomachs to cope with big meals. Therefore, to achieve the relatively high energy intake for their age, foods should be eaten as part of small and frequent meals.
Children should be encouraged to remain a healthy weight with respect to their height.
A healthy family lifestyle can help in the weight management of children.
A good supply of protein, calcium, iron, vitamin A and D, as part of a healthy, balanced diet, is important.
Calcium is needed for healthy tooth development, and together with vitamin D, can help develop strong bones.
Children should pay attention to dental hygiene and ways to prevent dental caries.
If children choose to eat food and drinks high in sugar occasionally, this should be done at mealtimes and not in between meals.
Brushing teeth twice a day with a fluoride toothpaste and regular dental visits are also important for dental hygiene.
Adolescence is a period of rapid growth and development and is when puberty occurs.
The demand for energy and most nutrients are relatively high. Boys need more protein and energy than girls for growth.
It is important to encourage an active lifestyle with a healthy, balanced diet during this time.
This is because good habits practised now are likely to benefit their health for the rest of their lives.
After menstruation begins, girls need more iron than boys to replace menstrual losses. It is recommended that teenage girls and women require 14.8mg of iron each day, while adolescent boys need 11.3mg of iron daily, but this reduces to 8.7mg for men aged 19 or over.
Iron from meat sources, e.g. liver, beef and lamb, is readily absorbed by the human body. Vitamin C helps to absorb iron from non-meat sources, such as green leafy vegetables, nuts, pulses, dried fruits (e.g. apricots), wheat flour and breakfast cereals. Therefore, drinking a glass of fruit juice or eating fruit and vegetables at mealtimes can help with iron absorption.
Nutritional requirements do not change much between the ages of 19 to 50, except during pregnancy and lactation.
On average, UK adults are eating too much saturated fat and salt from food, and not enough fruit and vegetables. A poor diet can lead to diseases such as obesity, cardiovascular diseases, cancer and diabetes.
To reduce the risk of developing these diseases, it is important to:
•eat a balanced diet;
• eat plenty of fruit and vegetables;
• drink alcohol in moderation;
• stay active;
• do not smoke.
Adults should aim for a healthy body weight for their height and try to keep it at that level.
The Body Mass Index (BMI) is a good indicator if a person is underweight, overweight or a healthy weight. To calculate BMI (kg/m2), divide weight (kg) by height (m) x height (m).
Recommended BMI range
Underweight less than 18.5
Normal 18.5 - less than 25
Overweight 25 - less than 30
Obese 30 - 40
Very obese over 40
Requirements for energy gradually decrease after the age of 50 as activity level falls.
Older adults is the term usually refers to people over the age of 65.
To maintain good health, it is important that older adults:
It is also important they keep hydrated by drinking plenty of fluid. Even minor dehydration can lead to health problems.
After menopause (when menstruation stops), women gradually lose bone strength.
Osteoporosis may occur when bones become weak, brittle and to break easily. This may lead to fractures in the wrist, back and hip.
Osteoporosis is a major problem in older people, especially women.
Older adults should have plenty of calcium intake from milk and dairy products, green leafy vegetables, beans, pulses, and products made from flour.
They should also remain active and have adequate vitamin D from foods such as oily fish, cod liver oil and margarine, or through the action of sunlight on the skin.
Everyone over 65 years of age is recommended to take supplements of vitamin D.