1. Diet Through Life

2. Energy needs change through life
Energy requirements change through life and depend on many factors, such as:
age;
gender;
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.

3. 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 to the mother, such as high blood pressure and diabetes during pregnancy as well as increasing the risk of complications to the baby.

4. 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.
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.

5. During pregnancy
During pregnancy, particularly in the last trimester, 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 (200kcal) 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 as increasing the risk of complications to the baby.

6. 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.
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.

7. 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.

8. 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.
Energy requirements increase during lactation (it has been calculated that the energy cost of breastfeeding is around 650 kcal/day). Some of this energy is obtained from fat stored during pregnancy. Mothers who exclusively breastfeed for 3-4 months require an extra 500 kcal/day, on average.
There are also increased demands for nutrients, such as calcium and vitamin D.
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.

9. 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.

10. Weaning
At around 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.
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, puréed vegetables and fruit and mashed potatoes.
It is recommended that infants under 6 months should not be given wheat (e.g. pasta) or other cereals that contain the protein gluten (e.g. cous cous). 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.

11. 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.

12. 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

13. 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.

14. 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.

15. 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.

16. 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 oily fish, 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

17. 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 less than 25
Overweight 25 - less than 30
Obese
Very obese over 40

18. 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 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.

19. 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.
As we progress through adulthood, bone resorption (replacement of old bone tissue) takes place at a faster rate than bone formation. This leads to a gradual fall in bone mass as we age. In women, bone loss is accelerated following the menopause.
Osteoporosis may occur when bones become weak, brittle and break easily. This can lead to fractures in the wrist, back and hip. Osteoporosis is a major problem in older people, especially women.
Having a greater peak bone mass (PBM) in early adulthood helps adults to start from a higher point from which bone mass will be lost during the ageing process.

20. 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. Older adults should also remain active.
Sources of vitamin D are from foods such as oily fish, cod liver oil and margarine, or through the action of sunlight on the skin. As we age, our skin is less efficient at making vitamin D from sunlight and it is unlikely that the diet alone will provide adequate vitamin D, so it is recommended that people aged 65 and over take a supplement of vitamin D.