In our third article about guidelines for
pregnant mothers, we will explore some of the important nutrients women require
during pregnancy, such as iron, folic acid, zinc, and vitamin D – for their own
health and the health of their babies.
Most women are probably aware of the fact
that they have a higher requirement for iron during their childbearing years to
make up for the menstrual blood they lose every month, and for the increased
demands of pregnancy and breastfeeding.
The best food sources of readily available
and easily absorbable iron (so-called haem iron), are red meat (beef, mutton,
pork), organ meats (liver, kidneys), poultry (chicken, turkey), egg yolk, and
fish. Although many plants contain relatively high levels of iron, other
compounds in the plant tissues such as phytic acid or oxalates tend to bind the
iron and change it into insoluble complexes which the human body has difficulty
Read: Iron deficiency anaemia
Spinach is a classic example: it has a
relatively high iron content (2.7 mg per 100g of raw spinach), but the iron is
bound to oxalates, which make it insoluble and lower its bioavailability.
Because many women enter pregnancy with an
iron deficiency (due to heavy menstrual blood loss, avoidance of meat and other
animal sources of iron), most doctors and clinics automatically prescribe an
iron supplement for expectant mothers. Unfortunately many of the iron
supplements used during pregnancy can cause unpleasant side-effects such as
nausea, vomiting, flatulence, constipation or diarrhoea.
Prof Tappenden reports that the current
approach to iron supplementation during pregnancy is firstly to encourage
pregnant mothers to eat an iron-rich diet, which is based on foods derived from
animals and iron-fortified cereals (in South Africa all maize meal and wheaten
flour is fortified with iron and most women in the USA obtain up to 50% of
their dietary iron from iron-enriched breakfast cereals).
Secondly, low-dose iron supplementation of
about 30 mg 1-2 times a week is advised to reduce the side-effects that can put
pregnant mothers off taking their iron supplements. Research showed that this
intermittent iron supplementation can achieve the same improvements in body
iron stores during pregnancy as a daily high dose of iron that may cause
If you are pregnant and your doctor has
prescribed an iron supplement for you that tends to make you feel nauseous or
causes constipation or diarrhoea, discuss this with the doctor to see if
you can use a lower dose iron supplement instead, but do not stop taking your
iron without first consulting your doctor or dietician. Your dietician can help
you with a diet that provides adequate supplies of readily available iron for
you and your baby.
The current recommendation in the USA is
that pregnant women should obtain 600 micrograms per day of folic acid. The
best dietary sources are:
- Legumes – dry cooked or canned beans, peas and
lentils and all soy products, wet or dry (e.g. tofu, soy milk, or soy meat
- Green leafy vegetables
- Citrus fruits (oranges, lemons, grapefruit,
- Other fruit
- Whole unprocessed grains such as crushed wheat,
unsifted maize meal, sorghum, millet and other whole grains
- In South Africa folic acid is added to wheat
flour and sifted maize meal and this fortification has reduced the incidence of
neural tube defect cases in newborn babies by 31%.
Interestingly folic acid supplements are
more bioavailable to the body than folic acid found in foods. This is often not
the case with other vitamins and mineral supplements, but synthetic folic acid
is absorbed twice as well as naturally occurring folic acid in food.
Read: No folly in folic acid
Supplementing your diet with folic acid at
the recommended rate is, therefore, a good idea and Prof Tappenden emphasised
that in the month before conception, all women in their childbearing years, as
well as pregnant mothers after conception should have 400 micrograms of folic
acid per day in addition to folate obtained from the above listed foods. As
conception cannot be accurately predicted, this recommendation applies for most
of the childbearing period if a woman is not practising birth control to
In addition to iron, zinc is probably one
of the most important minerals for healthy foetal development. Many women tend
to have a suboptimal zinc intake because of a variety of factors including:
undergone bariatric surgery which may hamper zinc absorption
- A vegan
diet which does not contain zinc that can be absorbed by the body
other diets that consist mainly of cereals or plants-based foods where zinc is
bound to compounds called phytates in the plant material and is not easily
- Zinc is
also added to the vitamin and mineral mix used in South Africa to fortify wheat
flour and maize meal, the two basic staple foods used in this country.
In situations where a pregnant woman may
develop a zinc deficiency, it is a good idea to use a zinc supplement to ensure
an intake of 11 mg of zinc per day.
It always seems strange to list vitamin D
as a vital nutrient – not because of its great importance in the human body (with
new roles being discovered every day), but because humans are basically able to
manufacture vitamin D in their own bodies, provided their skins are exposed to
sunlight for about 30 minutes daily.
During pregnancy vitamin D helps with the
development of the bones and teeth, and boosts the immunity of both the mother
and the child. But how many pregnant women spend 30 minutes a day sitting in
the sun? In the USA for example, many foods such as milk and dairy products are
fortified with vitamin D, but this is not the case in “sunny” South Africa.
modern lifestyles and fear of developing skin cancer have turned humans from
sun-worshipping, outdoor fanatics to pale couch potatoes huddled in front of
our TVs or over cell phones, laptops, tablets, Kindles and game consoles.
Wearing clothing which covers the entire body for religious reasons, living in
parts of the country that have little sunshine during the winter months or having
darker skins, all interfere with the natural process of making vitamin D under
the skin when it is exposed to sunlight.
Read: The miracle of vitamin D
Prof Tappenden recommends an intake of
vitamin D in the form of a supplement such as cholecalciferol at a dose of 600
IU/day. This may at present be difficult to achieve in our country because there
are currently no stocks of this vitamin available in the country because the
Medicines Control Council (MCC) is investigating the purity of the supplements sold
to the public. So, while we wait for the MCC to sort out this problem, all
pregnant women should spend half an hour a day exposing their skin to the sun
to make their own Vitamin D.
Because there are so many factors that
play important roles in the nutrition of women before, during and after
childbirth, it is really a good idea to consult a registered dietician for an
assessment of your health, diet and weight before you conceive and during
pregnancy to guide you through any dietary problems that may arise. Visit the
website of the Association for Dietetics in SA (ADSA) and click on ‘Find a Dietician’ to find a dietician
in your area.
Pregnancy should be a natural, happy time
when you are glowing with health and helping your baby grow strong and clever.
Remember that a dietician will help to allay your diet fears, sort out your
weight issues and advise you about diets, supplements and foods at any time
during your journey to motherhood.
Diet tips for pregnant moms – Part I
Diet tips for pregnant moms – Part II
Am I eating to optimise my pregnancy?
- Tappenden KA (2015). Eating for Two. Best
Practices for Maternal Nutrition. Paper presented at the Nutritional Solutions
CNE Event, 16 April 2015, Johannesburg.
Image: Pregnant mom with supplements from Shutterstock
Dr Ingrid van Heerden is a registered dietician and holds a doctoral degree in Nutrition and Biochemistry. She believes that "we are what we eat" and offers free nutrition and weight loss advice via her DietDoc service on Health24.com. Read more of her articles.