"...all doctors should be able to diagnose and treat nutritional deficiencies."

Royal College of Physicians. Nutrition and Patients: A Doctor's Responsibility. London 2002


This page has been printed from the www.stewartnutrition.co.uk web site.

Those Who Are Pregnant or Might Conceive

Good nutrition is particularly important in pregnancy because it is a time of increased need and nutritional problems that remain uncorrected just before or during the pregnancy can have life-long consequences. 
Excellent standard advice on diet and healthy lifestyle from:
the Food Standards Agency can be found at www.eatwell.gov.uk/agesandstages/pregnancy/ the Royal College of Obstetricians and Gynaecologists at www.youandyourfamily.co.uk 

Both sites give basic advice on the use of nutritional supplements to improve pregnancy outcome.  More detailed advice includes:

Indications and Contraindications to Nutritional Supplements in Pregnancy

Prevalence of deficiency in women age 19-34 yrs^
Who Should Take It
Who Shouldn’t Take It
Folic acid
400 ug/day
6 % low red cell folate
Almost everyone Those with vitamin B12 deficiency* see next section
Other supplements and dietary advice may occasionally also be required Those who need 5 mg/day dose:
See below
Folic acid
5 mg/day
6 % low red cell folate
Women with spina bifida Those with vitamin B12 deficiency* see next section
Women whose partner has spina bifida
Those who have already had a NTD pregnancy Some caution may be required in those with zinc deficiency as absorption may be reduced
Those taking antiepilepsy medication
Vitamin B12
5 ug/day
5% low serum vit. B12
Those with a poor dietary intake:  
  vegan or vegetarian diet
Those with poor absorption:
  Coeliac disease
  Crohn’s disease
Possibly some women on medication:
  The oral contraceptive pill
  long-term acid suppressant drugs
10-60 mg/day
7.5% anaemic
10% with low iron stores
Anaemic or low iron stores e.g. No one should take high-strength iron tablets regularly  without occasional medical assessment*
Heavy periods or history of anaemia
Vegans and some vegetarians especially if tea drinkers
Multiple pregnancy
Vitamin D
10 ug/day
20% have low blood levels
Those who are likely to be deficient: Very rarely hypercalcaemia*
 poor sun exposure especially office
 workers, city dwellers and others
 working long daylight hours
 those with dark skin  
 some vegans and those who do not eat
 oily fish
 multiple pregnancy  
 those on anti-epileptic medication
500 mg/day
7% have low dietary intake
Those with a poor intake due to a dairy-free or restricted diet Very rarely hypercalcaemia or a history of kidney stone formation*
Increased requirement due to:
  young person < age 21 yrs
  multiple pregnancy
  very petite frame or pregnancy-
  induced osteoporosis*
Vitamin A – retinol
Very rare
Only those with proven deficiency* Almost everyone
Vitamins C 1000 mg
and  vitamin E  400 IU
Vitamin C 4%
Vitamin E very rare
Those with proven deficiency High doses can increase the risk of low birthweight babies
Fish Oils providing
EPA+DHA = 1.0g/day
Possibly anyone who does not eat oily fish regularly** None.  But high doses may cause/aggravate skin itching
Multivitamins –standard type Most are not suitable as they often contain retinol.  Some vegetarian formulations might be acceptable. Those with an adequate diet
Multivitamins – prepregnancy type Those with a poor diet e.g. Those with an adequate diet
  Restricted or dairy-free diet
Increased requirement due to:
  young person Some with chronic illnesses:*
  multiple pregnancy   kidney disease
  some chronic illnesses*   liver disease
Most women with or at risk of multiple nutritional deficiencies*  

^ Data derived from National Diet and Nutrition Survey of British Adults 2003/2004 [internal link]
* These situations are likely to require expert medical and nutritional advice
** Currently the Food Standards Agency advise against all supplements containing retinol including fish liver oils but not fish (body) oils, which do not contain retinol.

Folate/Folic acid Supplements

It is standard advice for all women who are or might become pregnant to

  • take a supplement of folic acid (400 ug or 5 mg per day)
  • eat foods that are naturally rich in folate e.g. green vegetables, fresh potatoes and orange juice[internal link]
  • eat foods that have been fortified with folic acid e.g. some breakfast cereals and some margarines

The recommendation is that supplements should begin a few weeks before conception takes place in order to reduce the risk of spina bifida or a similar developmental abnormality occurring and should continue until the end of the twelfth week [external link]

Who needs 5 mg Folic Acid and not 400 ug Folic Acid?

Some women are advised by the Department of Health that they will require the higher dose supplement because of increased risk:

  • Women with spina bifida themselves
  • Women whose partner has spina bifida
  • Women who have already had a pregnancy affected by a Neural Tube Defect.  This may include some women with a history or miscarriage as 3% to 6% of miscarried pregnancies have a NTD
  • Women taking anti-epileptic drugs (especially if they have had an NTD pregnancy)

Department of Health.   Report on Health and Social Subjects. 50 Folic Acid and the Prevention of Disease.  Report of the Committee on the Medical Aspects of Food and Nutrition Policy 2000.  London: The Stationery Office.
Advice on the web site of the National Society for Epilepsy www.epilepsynse.org.uk/pages/info/leaflets/preg.cfm

Vegans and Vegetarians

Strict vegans and some vegetarians may be at risk of vitamin B12 deficiency and if they take folic acid alone they may mask its appearance and diagnosis.  Vitamin B12 deficiency can result in neurological damage developing in themselves as well as deformity developing in their infant or the pregnancy resulting in miscarriage. 
The simplest solution to this potential problem is for all vegan women or those with a poor intake of vitamin B12 or who have deficiency to take a pregnancy multivitamin providing at least 5 ug of vitamin B12 per daily dose and not just a supplement of folic acid and to make dietary changes to ensure that their diet is adequate in all other nutrients.
Approximately 5% of women of child-bearing age in Britain appear to have mild vitamin B12 deficiency [internal link]


Approximately 10% of women in the UK are either anaemic or have low iron stores and this can only be reliably assessed by blood tests.  It should be noted that the World Health Organisation level for haemoglobin below which anaemia is diagnosed in non-pregnant women is 12.0 g/dl but many laboratories and doctors in the UK still use the old limit of 11.5 g/dl [internal link]. 
Iron deficiency anaemia can become a problem in pregnancy despite the efficiency of absorption of iron from the diet increasing significantly. 
The commonest risk factors for iron deficiency are;

  • heavy periods
  • a poor dietary intake usually as a result of a low-protein vegetarian or semi-vegetarian diet especially if tea is consumed
  • multiple pregnancy
  • poor absorption of iron due to coeliac disease, which occasionally becomes apparent for the first time in pregnancy

These women may need an iron supplement and they should be tested for anaemia (haemoglobin concentration) and low iron stores (serum ferritin) before conceiving.  International standards have been set for these tests by the World Health Organisation as well as normal ranges in pregnancy.  [internal link]
Iron from supplements is better absorbed if they are taken with fruit or fruit juice and away from tea, other sources of tannin and unleavened bread including flat breads and chapatti.  Supplements should not be taken for prolonged periods without follow-up by your doctor and retesting as high doses taken long-term can reduce the balance of zinc, another important essential mineral in pregnancy.

Vitamin A - Retinol

Vitamin A is essential for growth but deficiency is thankfully rare in adults.  Despite supplements being rarely needed retinol is found in most multivitamins and an excess can result in fetal deformity.  It is not clear what the safe level in pregnancy is and therefore the advice of the Scientific Advisory Committee on Nutrition given in September 2005 is:

  • No supplements of retinol should be taken in pregnancy unless advised by a doctor.  This includes cod liver oil and most multivitamins.
  • Beta-carotene (vegetable-derived vitamin A) is safe to use in pregnancy up to 7,000 ug per day but is unlikely to be needed
  • Liver, which in the UK is exceptionally high in retinol and has three times the level of similar foods in the US, [internal link] should not be consumed at all in pregnancy

This advice supersedes that given by the Committee on Safety of Medicines in 1990 that products containing retinol should be labelled with the warning (where the maximum daily dose is greater than the Recommended Daily Allowance, RDA – currently 800 ug RE) “Do not take vitamin A supplements if you are pregnant or likely to become pregnant except on the advice of a doctor or ante-natal clinic”.
Similarly the laws governing the vitamin A content of margarine control its content to between 880 ug and 1000 ug per 100 g of margarine.
Anyone suspected of being vitamin A deficient should not try to conceive until their status has been assessed and any deficiency has been corrected. 

Vitamin D

The importance of vitamin D in human health including pregnancy was recently reviewed by the Scientific Advisory Committee on Nutrition, Update on Vitamin D, 2007. 
They comment that:
There is no survey of a nationally representative sample that assess vitamin D status in pregnancy
In British survey approximately 18% of white pregnant women and 50% of women of non-European ethnic origin may have a low blood level of 25(OH)D, which is the main type of vitamin D in the blood.
Low maternal levels may result in infants being at increased risk of becoming deficient and either developing rickets or having a low bone mineral density later in childhood.
A supplement of 10ug per day may be required by pregnant women who are at risk of deficiency but that higher doses, up to 50 ug and 100 ug per day have been given to breastfeeding women.
High maternal blood levels of 25(OH)D have recently been associated with an increased risk of atopic disease in the infant but this has yet to be confirmed.

The Scientific Advisory Committee on Nutrition. Update of Vitamin D. 2007. London: TSO.

Vitamins C and E

Preliminary work had suggested that a relative lack of these two vitamins which act as anti-oxidants might be a risk factor for the development of pre-eclampsia.
Studies have been undertaken to determine whether high dose supplements given to women in the early stage of pregnancy would reduce the risk of this developing.  Unfortunately one large trial, published in The Lancet medical journal in 2006 revealed that not only was there no benefit from supplements but there was a greater risk of having a low birthweight baby in those who were taking the supplement compared with those who were receiving placebo.

  • Supplements of high dose vitamin C (1 g or more per day) or vitamin E (400 IU or more per day) should only be taken in pregnancy on medical advice
  • Supplements of multivitamins containing vitamin C and E at low dose have not been reported as being associated with a poor pregnancy outcome and can be taken if clinically indicated
  • A small amount of vitamin C is added to Healthy Start Vitamins, which may be available on the NHS, and this helps to increase the absorption of iron from the diet and is perfectly safe

Who Might Need a Comprehensive Multivitamin and Mineral Preparation?

In view of the above it might be useful to give some indication for whom a pregnancy multivitamin/mineral supplement might be appropriate and what the characteristics of that supplement should be.

The purpose of the supplement should be to address the commonest deficiencies that are likely to be present in women of child-bearing age as seen in the National Diet and Nutrition Surveys of Adults 19 years and over [internal link] and Young People age 16 to 18 years [internal link].  They include iron, folate, vitamin B12, vitamin D, zinc and magnesium.  Ideally any dietary inadequacy should first be resolved by attention to the diet and the advice of the Food Standards Agency on healthy eating in pregnancy should be followed [external link].
These supplements would be most suitable for:

  • Those with proven deficiencies and who are trying to or might conceive
  • Those who have been deficient in the recent past and wish to prevent any recurrence e.g. mild iron or vitamin B12 deficiency
  • Those on a vegan diet or a poor quality vegetarian diet
  • Those who are on a restricted diet due to food intolerance or allergy e.g. cow’s milk allergy or coeliac diet especially in a vegetarian.
  • Those with poor sunlight exposure
  • Some who are taking anti-epileptic medication, steroids or other drugs with potentially anti-nutrient effects and are trying to conceive.  All such people should first seek the advice of their doctor or specialist.
  • Those with a multiple pregnancy whose diet may be inadequate for their needs
  • Many young people aged between 16 years and 24 years because some will still be growing and this age group is, according to the National Diet and Nutrition Survey, one of the highest risk groups for mild nutrient deficiency in the British population

The supplement should provide per daily dose at least:

  • folic acid 400 ug
  • vitamin B12 5 ug
  • vitamin D 10 ug

Some minerals may also be required and should the in the region of:

  • iron 5 mg to 15 mg
  • iodine 100 ug
  • zinc 5 mg to 15 mg


Calcium is a bulk mineral which is needed for healthy bones and teeth.  The amount required is such that it cannot be provided in a multivitamin and mineral preparation and will need to be taken separately.  It is often combined with vitamin D and supplements are best taken after food.
Supplements of calcium of 500 mg per day may be required by:

  • Those with a poor dietary intake e.g. milk-free diet
  • Those who are deficient in vitamin D
  • Those with high demand e.g. a multiple pregnancy especially if the mother is petite


Magnesium supplements are considered to be safe in pregnancy and may be required by those with a poor dietary intake, proven deficiency or for their laxative effect.  The Safe Upper Level is 350 mg per day.
Trials involving doses of approximately this amount have been conducted and some, but not all, have shown minor benefit.  Magnesium in very high doses is used in the treatment of high blood pressure and pre-eclampsia in pregnancy.

Copyright Dr. Alan Stewart M.B.B.S.M.R.C.P. (UK)M.F. Hom.
47 Priory Street, Lewes, East Sussex. BN7 1HJ
Tel 01273 487003 Fax: 01273 487576