"...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.

Minor Contraindications to Taking Nutritional Supplements

There are numerous, usually less serious and less common, contraindications to the use of nutritional supplements.  Some are common and others rare and many are only of mild significance but they may be of considerable importance to particular individuals.  It seems likely that other potential minor adverse reaction reports will be added to this already long list. 

Many of these clinically important situations are not covered adequately by the otherwise thorough EVM 2003 of report.  In many of the situations given below the advice of a doctor or experienced dietitian/nutritionist who can make an assessment of the need for and benefits and risks of supplementation should be sought.  In the case situations involving prescription medication usually adequate guidance is given in the accompanying patient information leaflet or can be obtained from www.medicines.org.uk 

Acute adverse reactions to a drug or food supplement can be assessed using the Naranjo algorithm which is a series of questions to which numerical scores are assigned that then allow the degree of probability to be assessed.  http://en.wikipedia.org/wiki/Naranjo_algorithm

Minor Contraindications and Warnings to the Use of Nutritional Supplements

Clinical Problem Potentially Harmful Nutrient Reasons for Caution
Obesity BMI >30kg/m2 Vitamin A – retinol*
Selenium >200 ug/day – Persistent use
Both supplements might aggravate obesity-associated liver disease.
Persistent use of selenium 200 ug/day for several years has been associated with a 55% increase the risk of  type II diabetes and those who are prone should consider a lower dose schedule
High Cancer Risk
due to: chemical exposure, personal or family history
Vitamin A – retinol*
Vitamin E
High dose supplements of these nutrients have been associated with an increased risk of cancer in clinical trials and they should be avoided or used with caution in those at increased risk. 
Renal Stones Calcium
Vitamin C >1g/day
Supplements could occasionally increase the risk of kidney stones.
Gastritis or Active Peptic Ulcer Zinc
Vitamin C
All of these supplements can sometimes cause gastro-intestinal irritation.  The risk is reduced if they are taken after food.
Muscle Soreness
after Exercise
Vitamin C 1g/day In a trial in physically active young men supplements of vitamin C 1g/day resulted in increased post-exertional delayed muscle soreness compared to placebo.
Diarrhoea Magnesium usually >150 mg
Iron usually >17 mg/day
Vitamin C >1000 mg/day.
Chewable supplements containing sorbitol or xylitol
Supplements of these three nutrients can cause or aggravate diarrhoea especially at high dose. 
The artificial sweeteners sorbitol and xylitol can sometimes cause diarrhoea.
Constipation Iron usually >17 mg/day Supplements of iron, especially high dose, can cause constipation as well as diarrhoea.
Vascular Disease:  Stroke, TIA or Coronary Disease Calcium > 1000 mg/day High dose supplements have been linked to an increase in the risk of vascular events in elderly women. A daily calcium dose of 500 mg and vitamin D 10 ug with healthy diet and exercise may be better.
Peripheral Vascular Disease Niacin > 100 mg/day Niacin at 1g/day increased plasma homocysteine levels by 55% in those with arterial disease. Use of other B vitamins may prevent this.
Parkinson’s Disease
or similar disorder of movement
   - diet
   - industrial exposure
   - supplements
Parkinsonism from manganese accumulation in the brain is usually resistant to levodopa treatment and can occur in association with liver disease or a portal-systemic shunt.  Chronic anaemia may increase the risk.
Fish Odour Syndrome Choline and lecithin granules A few individuals may produce malodorous sweat which is worsened by taking choline.
Vitamin A* –retinol, including cod liver oil
Folic acid < 400 ug/day*Vitamin C >1000 mg/day
Vitamin E >400 IU/day
Retinol has been associated with birth defects. 
Supplement must provide > 400 ug folic acid. 
High doses of vitamins C and E use have been associated with more low birthweight  babies.
Breast feeding High dose supplements Breast milk concentrates many nutrients and high dose supplements should be avoided unless indicated.
Riboflavin – vitamin B2*Vitamin B6*
Folic acid
Vitamin B3 – nicotinamideCalcium*Iron*
Vitamin C > 1g/day
Riboflavin may alter the activity of some antimalarial drugs.
Evening Primrose Oil is not always   contraindicated in epileptics
High doses of vitamin B6 and folic acid might rarely reduce drug effectiveness.
Nicotinamide may increase the blood levels of this drug; use with caution.
Minerals form an insoluble complex with Sotalol.  Separate them by at least 4 hrs.
The absorption of penicillamine can be reduced by these minerals.
May increase the level of oestrogen and possibly effects/side-effects
Vitamin B12 deficiency or anaemia  Folic acid > 1000 ug/day Folic acid supplements treat the anaemia but not the neurological effects of vitamin B12 deficiency and may thus delay the diagnosis.
Unexplained or persistent anaemia
Copper deficiency
Zinc > 25 mg/day High zinc intakes impede copper absorption leading to deficiency and anaemia, bone marrow failure and neurological problems.

* Relevant amounts are often found in standard strength multivitamin/multimineral supplements

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