Diet through life Extension
Learning objectives • To recognise the different key stages in life. • To understand why different amounts of energy and nutrients are required through life. • To describe the needs of different life stages to maintain health.
Energy needs change through life Energy requirements change through life and depend on many factors, such as: • age; • sex; • body size; • level of activity. The amount of nutrients needed to keep the body healthy is also different for each person.
Key stages in life The key stages in life include: • pregnancy; • infancy; • childhood; • adolescence; • adulthood. It is important to maintain good health through life.
Pregnancy A varied diet, providing adequate amounts of energy and nutrients, is essential both before a woman becomes pregnant (conception) and during pregnancy. The mother’s diet can influence the health of the baby.
Conception and early pregnancy Being a healthy body weight is important before pregnancy. Being underweight can make it more difficult to conceive. It can also make it more likely that the baby will 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.
Conception and early pregnancy:folate Folate (the natural form of folic acid found in foods) is needed for rapid cell division and growth in the foetus that takes place during pregnancy. It has been shown to reduce the chance of neural tube defects, such as spina bifida, in the unborn baby. Foods that are good sources of folate are green leafy vegetables, oranges, bread and fortified breakfast cereals.
Conception and early pregnancy: folate Women who are trying to become pregnant, or who are pregnant, should take a 400 microgram (μg) supplement of folic acid every day from the time they stop using contraception until at least the 12th week of pregnancy. This is because it is difficult to achieve the extra folate needed through diet alone. All women of child-bearing age are also advised to consume adequate amounts of folate. This is particularly important because it may take time for a woman to realise that she is pregnant.
During pregnancy During pregnancy, a woman’s nutritional needs increase to: • help the growth of breasts, uterus and placenta; • meet the needs of the growing foetus; • lay down stores of nutrients to help the growth of the foetus, and in the mother for lactation.
Extra energy needs during pregnancy During the first six months of pregnancy, most women do not need to eat more food than normal. The body becomes more efficient at absorbing and using nutrients from food. The Estimated Average Requirement (EAR) increases during the last three months of pregnancy by an average of 800kJ per day. Gaining too much weight during pregnancy can raise the mother’s blood pressure and increase her risk of being overweight or having diabetes.
Weight gain during pregnancy On average, if a woman eats to satisfy her appetite, her weight will usually increase by about 3.5kg in the first 20 weeks, then 0.5kg a week until the end of pregnancy. The total weight gain will be about 12.5kg.
Foods to avoid during pregnancy • Too much vitamin A during early pregnancy has been linked to birth defects. Vitamin A rich foods include liver and liver products, such as pâté, vitamin A supplements and fish liver oils. • Unpasteurised dairy products, such as Brie and Camembert, may be contaminated by Listeria, which can cause a miscarriage or infect the baby, so should not be consumed.
Food to avoid during pregnancy • Shark, swordfish and marlin. These types of fish may contain high levels of mercury, which can harm an unborn baby’s developing nervous system. • Pregnant women, and those who are trying to conceive, are advised to stop drinking alcohol. Alcohol may damage the unborn child.
Birth A normal pregnancy is between 37 and 41 weeks. On average, new-born babies weigh around 3.3kg. Boys are approximately 300g heavier than girls.
Infant feeding The process of producing breast milk is called lactation. Breast milk provides all the energy and nutrients a baby needs for growth and maintenance during the first 4 to 6 months of life. 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.
Breast feeding A mother who is breast feeding requires extra energy and nutrients. Some of this requirement is supplied through extra stores laid down during pregnancy, in addition to the diet. The extra EAR for energy during lactation is 1900kJ per day during the first month, and later depends on how long breast feeding is continued. There are also increased demand for nutrients, such as calcium, phosphorous, vitamin A and C.
Breast milk On average, 100g of breast milk provides: ● 289kJ energy ● 1.3g protein ● 4.1g fat ● 7.2g carbohydrate ● 34mg calcium 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.
Bottle feeding If a mother does not wish to breast feed her baby, or finds it difficult, she can use an infant formula (also known as ‘baby milk’) from a bottle with a teat. Infant formulas do not provide any of the factors that help prevent infections. It is important to note that once a mother has started to bottle feed her baby, it is difficult to change to breast feeding. The Department of Health recommends exclusive breast feeding for the first 6 months of life.
Weaning After 4 to 6 months of age, milk no longer fulfils all the baby’s needs for energy and nutrients. The baby must be given other foods in addition to breast milk or infant formula. This process is called weaning. Weaning before this age is not recommended, as the intestines and kidneys may not be able to process the food.
Weaning Different foods can be used during weaning, but they must be semi-fluid and soft, since the baby has no teeth and cannot chew, e.g. rice, puréedvegetables and fruit and mashed potatoes. It is recommended that infants under 6 months should not be given wheat or other cereals that contain the protein gluten. This is to avoid a possible allergic reaction to gluten, called coeliac disease. Eggs should be cooked until both the white and yolk are solid. Raw eggs and foods that contain raw or partially cooked eggs should be avoided due to the risk of food poisoning from Salmonella.
Supplements After the age of 6 months, infants receiving breast milk as their main drink or receiving less than 500ml of infant formula each day, should be given supplements of vitamins A, C, and D in the form of liquid drops. Between the age of 1 to 5 years, vitamins A and D supplements should be given unless the baby receives adequate intake and exposure to sunlight. 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.
Childhood The energy requirements of children increase rapidly because they grow quickly and become more active. This means they have a high energy requirement for their size. 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.
Healthy weight in childhood 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.
Childhood A good supply of protein, calcium, iron, vitamin A and D, as part of a healthy, balanced diet, is essential. Calcium is needed for healthy tooth development, and together with vitamin D, help develop strong bones.
Dental hygiene Children should pay attention to dental hygiene and ways to prevent dental caries. If children choose to consume 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 using dental floss will help maintain healthy teeth. Regular dental visits are also important.
Foods to avoid in childhood Nuts • Whole or chopped nuts should not be given to children under 5 years to avoid choking. Some children may also be allergic to nuts. Deep sea fish • Shark, swordfish and marlin contain relatively high levels of mercury, which may damage the developing nervous system of children.
Adolescence 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 due to their later growth spurt. A growth spurt begins around 10 years of age in girls and 12 years in boys. In both sexes, an average of 23 cm is added to height and 20 to 26kg in weight. Before adolescence, both girls and boys have an average of 18% body fat, during adolescence, this increases to around 28% in girls and decreases to around 15% in boys.
Weight management in adolescence Adolescents should have plenty of energy in their diet for rapid growth. However, some adolescents tend to eat more than they need and become overweight. It is important to encourage an active lifestyle with a healthy, balanced diet during this time, because good habits practised now are likely to benefit their health for the rest of their lives.
Adolescence After menstruation begins, girls need more iron than boys to replace losses. It is recommended that teenage girls and women require 14.8 mg of iron each day, while adolescent boys only need 11.3mg of iron per day, but this reduces to 8.7 mg of iron daily for men aged 19 or above. Some women have very high iron requirements because they have large menstrual losses.
Adulthood Nutritional requirements do not change much between the ages of 19 to 50, except during pregnancy and lactation. On average, UK adults are having 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.
A balanced diet for adults To reduce the risk of developing these diseases, it is important to: • eat a balanced diet with plenty of fruit and vegetables; • opt for healthier fats; • get enough dietary fibre (NSP); • keep well hydrated; • stay active; • drink alcohol in moderation; • not smoke.
Healthy weight for adults 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
Older adults Requirements for energy gradually decrease after the age of 50 as activity level falls. Older adults is the term usually refer to people over the age of 65.
Older adults Older people may eat less for different reasons, for example: • difficulty in chewing and swallowing; • dental problems; • changes in sense of smell and taste; • difficulty in shopping, preparing and cooking food; • living alone; • financial problems; • illness. To maintain good health, it is important that older adults: • enjoy their food; • keep active; • have adequate nutrient intakes.
Healthy ageing Older adults should adopt a healthy, balanced diet to maintain health. It is also important they keep hydrated by drinking plenty of fluid. Even minor dehydration may lead to health problems.
Older adults After menopause (when menstruation stops), women lose bone strength at an increased rate. Having a great peak bone mass (PBM) in early adulthood helps adults to start from a higher point from which bones will be lost during the ageing process. As people age, osteoporosis may occur when bones become weak, brittle and 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 Older adults should have plenty of calcium intake from milk and dairy products, green leafy vegetables, beans, pulses, and products made from white and brown flour, which are fortified with calcium in the UK. 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.
Review of the learning objectives • To recognise the different key stages in life. • To understand why different amounts of energy and nutrients are required through life. • To describe the needs of different life stages to maintain health.