There are several common medical and other situations that can have major implications as to the safety of using supplements. An error of judgement on the part of the individual, retailer or health practitioner may have serious health consequences for the patient. The main issues which are summarised in the accompanying table are:
Additionally, in each of these situations it is likely that your GP or specialist are involved in your health care and they must be informed of your use of nutritional supplements.
Details of reports of common and uncommon adverse reactions to nutritional supplements
have increased substantially and the US based National Institutes of Health have an on-line listing of them at http://dietarysupplements.nlm.nih.gov/dietary/ingred.jsp . They are accessed by selecting a nutrient from the Active Ingredients Alphabetical List, scrolling down to Adverse Effects (in humans) and clicking on the section Adverse Effects Literature [PubMed], which then takes you to a PubMed listing of relevant papers for that particular nutrient. There would appear to be several thousand reports in total, many but not all of which relate to the use of nutritional supplements.
Information on interactions between nutritional supplements and medication is often found in the in-pack leaflet provided by the pharmaceutical company at 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
|Clinical Situation||Number of
|Supplemental Nutrients to be avoided or used with caution||Comments and Alternative Preparations|
(and herbal products)
Folic acid and vitamin B* complex/multivitamins*
Iron and other minerals
|Use of multivitamins and fish oils up to 1g EPA + DHA per day are usually tolerated. Increased monitoring of INR is prudent when supplements are commenced or changed.
Supplements containing folic acid should not be taken on the same day as methotrexate.
Seek medical advice.
These minerals can reduce the absorption of the antibiotic if taken at the same time.
|Possibly many nutrients especially antioxidants, vitamin B1 – thiamin, folic acid and strong multivitamins||Seek advice especially if cancer is rapidly growing.
Supplements are best given only if clinically indicated e.g. weight loss or proven deficiency and are unlikely to interfere with treatment.
High doses of retinol*, beta-carotene* and vitamin E
|Encourage a healthy diet. Some elderly patients and those with poor intake may need some supplements.|
>14 units/week – women
>21 units/week – men
Beta-carotene*Iron*Vitamin B1 - thiamin
|Retinol and possibly beta-carotene may worsen alcohol-induced liver disease.
Iron excess may occur in alcohol-induced liver disease without haemochromatosis.
Use of vitamin B1 alone may worsen or mask the diagnosis of alcohol-induced vitamin B3 deficiency - neurological pellagra. Use of high-strength vitamin B complex is recommended
|Smoking||12.5 m||Beta-carotene*||Supplements but not diet may increase lung cancer risk.|
|Asbestos Exposure||< 200,000||Beta-carotene*||Supplements but not diet may increase lung cancer risk.|
High doses of many nutrients
|Use folic acid or specialised multivitamin supplement and promote healthy eating.|
|Heart Attack||250,000/year||Beta-carotene*||Fish oils are often recommended|
7.0m at risk
Cod Liver Oil
|Calcium and vitamin D are given routinely. Some elderly may need other supplements.|
Cod Liver Oil
|Regular consumers (equal to or more than 1 portion per week) of liver are advised to avoid all Retinol containing supplements. Excessive intake amy increase the risk of Osteoporosis or Retinol toxicity.|
or abnormal liver tests
abnormal liver blood tests
|Retinol in high doses.
|Some supplements, especially in high dose are toxic to the liver. Expert advice is needed if liver disease is progressive.
Deficiencies of vitamins A, B as well as zinc can occur.
|Renal Impairment||24,000 receive dialysis
Kidney disease Stage 4/5
Magnesium* and potassium
|Avoid all supplements and seek expert medical advice.
Deficiencies of zinc and vitamin B are not uncommon and supplements may be safe.
and any other cause of iron accumulation
Vitamin C >500 mg/day
|Seek expert advice.
High dose vitamin C may increase iron absorption.
due to; sarcoidosis,
TB and renal disease
Mild cases of hypercalcaemia
may easily be unnoticed
|Seek advice about all calcium and vitamin D supplements.
Retinol excess may cause hypercalcaemia in those with renal impairment.
|Type 2 Diabetes||<3 m||Fish Oils||The risk/benefit of fish oils in type 2 diabetics without hypertriglyceridaemia is unclear as blood glucose levels may rise and fat utilisation may be reduced by supplements in such patients.|
Approx. 2-5% of British >65 yrs have high copper intakesApprox. <1.0% of adults
|Copper >1.0 mg/day
Total Intake >2.0 mg
(approximately)/dayFolic acid supplements >400 ug/day and
Total Intake >1000mg/day
|High intakes from diet and supplements together with a diet high in saturated and trans fats is associated with accelerated cognitive decline
High folate/folic acid intake by those who are vitamin B12 deficient may mask and delay the true diagnosis as to the cause of their mental decline
* Relevant amounts are often found in standard strength multivitamin/multimineral supplements