Women’s Extra Nutritional Needs

A woman’s reproductive life - encompassing menstruation, pregnancy, lactation and menopause - means that her nutritional needs differ greatly from those of a man. The popularity of crash dieting has meant that nutritional deficiencies are especially common amongst younger women. Good nutrition means eating a wide variety of foods every day, which isn’t possible on a restrictive diet.

Food and premenstrual syndrome (PMS)

The interplay of hormones throughout a woman’s menstrual cycle impacts on her body and state of mind. Energy intakes are generally higher in the premenstrual phase than after menstruation. Some women also experience food cravings as their period approaches. Eating high protein foods every few hours can often temper the cravings or stop them altogether. This should not be done at the expense of other food groups, especially carbohydrates, which should form the basis of the diet.

Fluid retention is common in the days leading up to a period because certain hormones encourage the body to hold salt, or sodium. The more sodium held, the more fluid retained in the tissues. Some research indicates that increasing the intake of calcium-rich foods, such as dairy products and leafy green vegetables, can ease fluid retention. Other common symptoms of premenstrual syndrome (PMS) include moodiness, tiredness and constipation.

Foods that may help to relieve the symptoms of PMS include:

• Fruits and vegetables
• Cereal foods (preferably wholegrain)
• Legumes

Limiting refined sugar, salt, red meat, animal fat, alcohol, caffeine and tobacco may also help to ease symptoms. There is some evidence that taking B group vitamins during this time can help, particularly vitamin B6. Light to moderate exercise, such as a 30 minute brisk walk each day, has also been shown to noticeably reduce symptoms of PMS.

Iron and anaemia

Iron is a mineral that works in conjunction with other substances to create haemoglobin, the compound that carries oxygen in the blood. Women and men metabolise iron from food at roughly the same rate. However, while men need around 7mg of iron in their daily diet, women need up to 16mg. This is to make up for the amount of iron they lose in their menstrual period, which averages around 1mg or so lost for every day of bleeding.

Iron deficiency is the most common nutrient deficiency that affects women. Insufficient iron can lead to anaemia, with common symptoms including tiredness and breathlessness. Iron deficiency in pregnant women increases the risk of prematurity, or delivering a low birth weight baby, which can have a negative impact on the short and long term health of the baby. Good sources of iron include legumes, nuts and leafy green vegetables. Iron absorption can be impaired by very high fibre diets, alcohol and the tannic acid in tea.

Vitamins, minerals and pregnancy

The extraordinary demands on the female body during pregnancy can lead to nutritional deficiencies if the mother does not alter her diet. Pregnant women only need 300 kilocalories (kcal) more than non-pregnant women, which can be achieved by consuming just one extra serving from each of the five food groups daily. The most common deficiencies in pregnant women include:

• Calcium - calcium absorption more than doubles during pregnancy, and the mother stores most of this in her bones. The calcium stored in the mother’s bones early in pregnancy is withdrawn to provide calcium to the foetus in later pregnancy. Increasing calcium intake during pregnancy helps to conserve the mother’s bone mass, while meeting the needs of the foetus. Good sources include dairy products (milk, cheese and yoghurt).
• Folic acid - the recommended daily intake (RDI) for folic acid doubles during pregnancy. This is because folic acid is needed for the development and growth of new cells. Research suggests that insufficient folic acid at conception and in the first trimester of pregnancy can increase the risk of neural tube defects in the unborn baby. Good sources of folic acid include leafy green vegetables and cereals.
• Iron - although iron absorption increases during pregnancy, blood volume increases as well. Iron is involved in the process of oxygen transport. Enouth iron is drawn in by the developing foetus to last through the first five or six months after birth, when its only food is iron-poor breast milk. Iron supplements are frequently prescribed for pregnant women, especially during the third trimester. Iron-rich foods include leafy green vegetables.
• Zinc - needed to maintain the health of cells. Taking iron supplements may interfere with the absorption of zinc, so women taking iron supplements may also need zinc supplements. Leavened wholegrain products can also be helpful (yeast helps release the bound zinc).

Deficiencies during lactation

Nutrient requirements generally increase during lactation (500 kcal) than in pregnancy (300kcal). The nutrients that are particularly important during this time are protein, calcium, vitamin C, folate, zinc, magnesium, vitamin B6 and fluids. Women who are breastfeeding can develop calcium and iron deficiencies. This can be addressed by increasing the amounts of calcium and iron rich foods eaten every day or, if necessary, taking supplements.

Calcium and osteoporosis

Osteoporosis is a disorder characterised by a thinning of the bones until they are weak and easily fractured or broken. Women are at greater risk of developing osteoporosis than men, particularly after menopause, because oestrogen levels are reduced. There are many factors involved, for example:

• Low calcium intake during the growing years increases the susceptibility to osteoporosis later in life. Poor calcium intake early in life is also linked to deficiencies of vitamin D, calcium and possibly fluoride. Scientists agree that bone strength in later life depends on the development of bones earlier in life, and that adequate calcium intake during youth is essential to achieve peak bone mass.
• Diet and exercise are also important. The sex hormones (in particular oestrogen), exercise, smoking, and what we eat and drink can all affect calcium absorption and excretion. Salt, caffeine and alcohol interfere with the balance of calcium through urinary losses and should be consumed sparingly.
• Crash dieting has been associated with the development of osteoporosis due to the tendency to cut out dairy foods.
• Animal protein, eaten in large amounts, also increases urinary calcium loss - a major contributor to calcium balance. This does not occur with plant protein.

Vitamin D and calcium

Vitamin D increases calcium absorption and is required for normal bone metabolism. There are a few food sources of vitamin D. Good sources of calcium include dairy foods, calcium-fortified soymilk and sesame seeds. However, for the women who cannot consume these foods, calcium supplements may be desirable.

Things to remember

• Iron and calcium deficiencies are common in women.
• Vitamin B6 can help ease the symptoms of premenstrual syndrome.
• Foods like tea, alcohol, caffeine and salt can interfere with the absorption and excretion of important minerals.