Major life stages of females dictate nutritional requirements - By David Stache

Major life stages of females dictate nutritional requirements

By David Stache

Introduction
Great physiological changes occur throughout a female’s life and her health status is affected by biological, environmental and social factors. Diet quality is important in order to obtain the necessary range of vitamins and minerals, and the timing of when different nutrients are needed is crucial (Bartley et al., 2005).

Deficiency of nutrients varies greatly between the developed and industrialised world. However, low dietary intake is the main cause of these deficiencies in the developed world. Other factors such as medications, genetic factors, nutrient interaction and diseases such as diabetes, will play a role (Bartley et al., 2005).

Each major stage in the life cycle of a woman will be analysed, and the fundamental factors discussed.

Infants
The principal nutritional demand for infants is for growth, which is highest at birth. The proportion of protein required is 64%, which decrease thereafter to 35% at the 3-6 months and 16% at 1-2 years of age (Lawson, 2005).

Human milk is considered to provide the correct nutritional needs for an infant until 6 months and in addition transfers an immunological advantage to the infant. Infants that are fed on formula are suggested to need a slightly increased energy intake to have the same growth velocity as infants fed on breast milk. Fats continue to be an important contributor of energy for the first two years of life. An infant’s ability to synthesis glucose is limited, especially in a preterm infant, and 40% of their energy is obtained from simple sugars to maintain their blood glucose levels.

Amino acid requirements change throughout infancy. Some nonessential amino acids cannot be synthesized fast enough for the high synthesis requirement of the infant, and certain components of breast milk, is assumed to help to meet this high demand.

Nutrients for bone development, such as vitamin D, phosphorus, magnesium, and fluoride are required. The calcium content in breast milk is at an optimum level, and no supplementation is required for the first six months. The calcium in formula is not absorbed as efficiently as in breast milk, and the levels are increased to ensure comparable retention levels (Greer et al., 2006). Preterm babies have a higher calcium requirement, and formulas are fortified with calcium and vitamin D.

Preterm infants have low stores of minerals and require iron supplements until the age of one (Klemm, 2006). Selenium and copper deficiencies are also common in preterm and low weight infants. Breast milk is low in iron, but infants born at term have sufficient iron stores to last until they have doubled their birth weight. After 6 months, the requirement for iron is high. Infants and young children that are on a diet of cow’s milk run the risk of an iron deficiency, as well as a copper deficiency. Iron is important in brain development, and a deficiency may lead to permanent motor damage. Iodine is essential for thyroid function, which plays an imperative role in growth and development. Hypothyroidism is the consequence of iodine deficiencies, and this is often seen in developing countries. Zinc requirement is high in children due to growth and after the age of 6 months, zinc-containing food or fortified formula is required. Zinc deficiencies are fairly common, leading to low weight gain and growth.

Children
Children grow rapidly and require adequate nutrients to allow for this growth, and neurological development. Sufficient quantities of protein and carbohydrates are required for building and repairing bodies and iron is needed for blood and lean muscle. Infants and children who are stunted are able to catch up until the end of puberty, but the negative effect on cognitive function may be permanent. There is a strong association between childhood nutrition and disease later in life, including cardiovascular diseases (CVD) and diabetes.

Calcium deficiencies can lead to rickets, although this is generally only seen in children where there is an absence of dairy products in their diet. Intake of calcium is important to ensure optimum bone density; with a difference in proportions for boys and girls, to account for the greater bone mass in boys. Phosphorus recommendations show similar differences.

Fibre intake should be limited as the body isn’t able to cope, and too much fibre reduces the amount of minerals absorbed, such as calcium and iron and results in a bulky, low energy diet. There are certain health benefits to dietary fibre, including normal laxation and a lower risk of gastrointestinal disease, reduction of cholesterol, and the reduced risk of chronic disease later in life, including diabetes, CVD and cancer. There is an inverse relationship between the intake of dietary fibre and obesity. This may be due to the fact dietary fibre induces satiety, has a negative effect on metabolized energy, and modulates insulin response to carbohydrate (Williams, 2006).

Vitamin C is of particular importance in childhood not only as its role as a vitamin but also to improve the absorption of non-haem iron. There is also a link between low levels of vitamin C intake and asthma in childhood (Harik-Khan et al, 2004).

Vitamin A deficiencies are often seen in developing countries, which may lead to complete blindness in children. It is recommended that children between the age of 6 months–5 years should receive supplements as sufficient quantities are seldom obtained from weaning foods. Susceptibility of infection is linked to low vitamin A levels. A controlled trial undertaken in a developing country showed that there was a decrease in mortality in infants in a hospital that provided vitamin A supplements (Klemm, 2006).

Adolescents
Adequate nutrition is essential for rapid growth, physical maturation, to establish body nutrient reserves before pregnancy, and establish good nutritional status, such a skeletal health (Bartley et al, 2005). There is a slight increase in energy requirements once puberty has begun. The pubertal growth spurt begins two years earlier in girls than in boys, at around the age of nine. Important nutrients for growth include protein, iron, calcium, vitamin C, vitamin D and zinc.

Calcium in particular, plays a crucial role in bone development, and with the influence of sex hormones, bone density increases (Ruxton and Fiore, 2005). Bone density peaks in the early twenties, and a low bone density at this time increases the risk of osteoporosis later in life, especially in women. The International Osteoporosis Foundation estimates that 1 in 3 women are at risk for osteoporosis, compared with 1 in 8 men. Preventative measures include following a healthy diet that is rich in calcium and vitamin D, as it stimulates the absorption of calcium in the intestine. Overweight children are also shown to have a lower bone mass and bone area, relative to their body mass, and are more prone to fractures (Greer et al., 2006).

Peak calcium accretion rate is achieved at 12.5 years in girls, and there is a 3–4 year period whereby increased bone mass acquisition is the 40% bone mass accumulated for life. Supplementation needs to occur over a longer period, as even 1–2 years does not have a marked benefit on maximum peak bone mass (Greer et al., 2006). Calcium and vitamin D used together are the best defence. The action of each relies on the other, and where they act alone, the results are complementary (Heaney, 2007).

In the prepubertal stage, there is little difference in body fat composition in girls and boys. However during puberty, girls develop adipose tissue at a higher rate than boys, with stores being laid down on the hips and breasts.
Under-nutrition during adolescent may result in slow height growth, lower peak bone mass and delayed puberty. On the other hand, obesity in girls may bring about an early menarche, which then increases the risk of breast cancer later in life (Ruxton and Fiore, 2005). The onset of menarche is triggered by level of body fat, while strenuous exercise may delay menarche.

Additional iron may be required when menstruation becomes regular and heavier. Adolescents who experience growth spurts and have just begun menstruating are at particular risk for iron deficiency (Akabas and Dolins, 2005).

Adulthood in women, including pre-conception, pregnancy and lactation.
Body weight plays a crucial role in a women’s ability to conceive. Under- and overweight women battle to conceive. What is imperative during this stage of a women‘s life cycle is to ensure that she is able to provide the foetus with sufficient quantities of nutrients. A pregnant woman needs an extra 300 kcal per day, although pregnant adolescents, athletes and underweight women require more. Energy requirement during lactation is higher, so intake of protein, vitamin and minerals should be higher. If the mother is deficient in certain nutrients, the quantity rather than the quality of human milk is affected (Bartley et al, 2005).

The role of vitamin B12 and folate before conception and during pregnancy is well documented. Vitamin B12 activates the folate enzyme. Folic acid should be taken before pregnancy, right up to the twelfth week to reduce the risk of neural tube defect. Additional benefits of folic acid include lowering homocystein levels and associated morbidity and mortality from CVD and even neurological deterioration during old age (Bartley et al, 2005).

Iron requirements increase during pregnancy, and supplementation is encouraged to reduce the risk of pregnancy anaemia (Sanchaisuriya et al, 2007). Iron levels have a marked effect on the pregnancy outcome, include pregnancy mortality and cognitive development. Iron is needed for haemoglobin production, and it is important that sufficient quantities are taken before pregnancy. The body minimises the loss of iron during pregnancy by stopping menstruation. Additional iron is required for the enlarged blood volume for the placenta and foetal needs. An excess of iron needs to be avoided as the body does not excrete the surplus, and has been linked to liver disease and an increase risk of CVD. Additionally, the intake of supplementary iron in postmenopausal women has been associated with type 2 diabetes (Akabas and Dolins, 2005).

Vitamin A deficiency during pregnancy can lead to reduced maternal immunological protection and negatively affect the infant’s immune system (Bartley et al, 2005). Vitamin A supplementation is recommended for pregnant women towards the end of their term as pregnancy and lactation will deplete the mothers stores (Klemm, 2005). However excess vitamin A can lead to an increased risk of miscarriage and congenital malformations.

Essential fatty acids are important for the growth of the foetus and play a role in the early development and resistance to infection. The brain is largely composed of lipids, and is deepened on long chain omega-3 and omega-6 for growth and structure. Obesity during pregnancy increases the risk of maternal complications, including gestational hypertension, gestational diabetes, the need of a caesarean delivery as well as hospitalization before delivery. There is also evidence to support the increased risk of birth defects correlated with maternal overweight and obesity (Bartley et al, 2005).

Old age
Menopause brings about physiological changes in women, and increases the risk of cardiovascular disease and osteoporosis. Genetics plays a large role in health, and can be positively influenced by diet. Women also tend to have longer life cycles than men, and may be more susceptible to disease and disability.

The normal consequences of aging, including acute and chronic illnesses, organ failure, medication, will all influence nutrition and requirements. Research on nutrition in the elderly is limited as there are many different factors affecting nutritional needs. Customizing a diet is often required depending on the health problems experienced by the elderly women. Nutritional status in the elderly affects various health issues, including immunity, pressure sores and impaired muscle function (Izawa et al., 2006).

A study undertaken by Giustafsson et al., 2005 showed that a loss of appetite was a problem among the women studies. On the other side of the spectrum are the women that gain weight in old age, leading to the risk of CVD and diabetes.

Certain food choices can prevent age-related diseases and improve quality of life. Limiting the amount of polyunsaturated fatty acids and saturated fatty acids will reduce the incidence of CVD and arthrosclerosis (Hyland and Barnett, 2005). Anaemia is common in the elderly and the intake of calcium and vitamin D is still important. Folate should be consistent in the diet for the prevention of heart disease and lowering the risk of certain cancers; while low levels of folic acid have been linked to osteoporosis and neuropsychiatry disorders (Bartley et al, 2005). Fibre is an essential part of the diet as it prevents constipation and biventricular disease.

The protective effect of vitamins and antioxidants is needed. For example, increased amounts of vitamin C, E and carotenoids delay the development of various forms of cataracts, while a deficiency in chromium has been linked with an increased risk of diabetes mellitus (Hyland and Barnett, 2005). Nutrients that also combat inflammatory response should be included in the diet, now that the role of the inflammatory process in aging is well documented.

Diet has been documented to have an influence on longevity. A study undertaken evaluating healthy men and women over the age of 60 compared individuals that adhered to a healthy Mediterranean diet that showed a decrease in overall mortality (Trichopoulou et al., 2005).

Nutrition and disease
There is a link between certain cancers and a deficiency of certain nutrients. A study undertaken by Xu, et al, 2007 showed that an increase in vitamin E and beta-carotene, reduced the number of endometrial cancers in a population that had a deficiency in these nutrients. The benefits of a healthier diet, thereby increasing the intake of a number of essential nutrients, have shown more of an advantage than supplements, to reduce the incidence of certain cancers. In fact, supplementation has in some cases increased the risk of tumour recurrence and may promote the growth of certain tumours, as seen with the supplementation of beta-carotene and lung cancer (Shaw, 2005)

It is important to include the intake of antioxidants, noticeably vitamin C, vitamin E and folic acid to decrease the risk of various cancers (Benzie and Strain, 2005). Various other nutrients confer an antioxidant defence. Further investigation is needed to confirm if it is a combination of antioxidants, or one specifically, that provides this protection. The recommendation is five fruit and vegetables daily will help prevent 30-40% of cancers.


Conclusion
Diet plays an important role in the longevity and health throughout a woman’s life and it is clear that the need for certain nutrients changes over a life cycle. For example, high levels of cholesterol are a risk factor for CVD in young and middle age adults, but Weverling-Rijinsburger et al., 1997, suggested that it may be advantageous after the age of 80.

Correcting deficiencies or maintaining a healthy diet can be controlled through food and/or supplements. Fortification of foods with micronutrients is proving successful in many cases, especially when the staple food does not provide adequate nutrition. Fortification of salt with iodine and vitamin A and D in milk, and formula for infants with various micronutrients has shown some success. In the US, fortification of flour with folic acid has resulted in a decrease in neural tube defects.

Women’s health is closely linked to the family unit, and continual research and aid will ensure healthier future generations.


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