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

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

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Safe Upper Levels and Guidance Levels for Vitamins and Minerals

A summary of the main recommendations of the Expert Committee on Vitamins and Minerals of the Food Standards Agency published in May 2003 are provided in the accompanying table.  The following sections are included:

Safe Upper Levels and Guidance Levels

Safe Upper Levels and Guidance Levels are defined as: “… the doses of vitamins and minerals that susceptible individuals could take daily, on a life-long basis, without medical supervision.”
The wisdom of this definition is questionable and it has yet to be tested in law.
The figure for SUL or GL sometimes relates to the amount provided by supplements and sometimes to the Total Safe Intake, TSI, provided by food, water and supplements.

The only way to find out if your intake of an essential nutrient from supplements (and sometimes diet) exceeds the Safe Upper Levels and Guidance Levels is to laboriously check that your total intake from all supplements does not exceed the levels set.  There may be no particular consequences if they do in the short term.  However it would be prudent to obtain appropriate advice about the need for supplementation from your doctor or a dietitian/nutritional therapist.

The Total Safe Intake from all sources, food and supplements, will need to be estimated for vitamin A – retinol and sometimes the trace elements manganese, copper, zinc and iodine.  To do this the Dietary Sources of Essential Nutrients will need to be consulted.
For retinol the Total Safe Intake is likely to be exceeded by those who consume liver in the UK twice per month or more or have a very high intake of dairy foods as well as high dose supplements.  The same could also be true for some of the above minerals if liver, shellfish and some other foods are consumed regularly as well as supplements.

The information in the 360 page report has been summarised for this site into  two tables

Up to date referenced information on contraindications is available in two tables:

Prevalence of Deficiency in the British Population

Data on the prevalence of deficiency of each nutrient from the National Diet and Nutrition Surveys of adults and the free-living elderly are also included.

Possible Adverse Effects if SULs/GLs are Exceeded

Details of the more important adverse effects of essential nutrients mentioned in the report are given.  However, reports of adverse effects since 2003 that did not form part of the above report of The Expert Committee on Vitamins and Minerals may be covered in the Major Contraindications Table [internal link] are included.

Additional Risk Factors for Toxicity and Author’s Clinical Comments

Many of the adverse effects of nutritional supplements can be explained, in part, by the presence of other conditions that alter the metabolism or excretion of the nutrient.  The author has attempted to keep the lists up-to-date but there can be no guarantee that they are entirely comprehensive and they should not be considered a substitute for assessment of the risks and benefits of nutritional supplementation by your doctor or a qualified nutritionist/dietitian.

Safe Upper Levels and Guidance Levels for Vitamins (2003)*
Nutrient
Safe Upper Levels or
Guidance Levels

Total Safe Intake from Food & Supplements

Prevalence** of Deficiency in the
British Population
Possible Adverse Effects  
if Safe Upper Levels or Guidance Levels are Exceeded
Additional Risk Factors for Toxicity and
Author’s Clinical Comments
Adults
19-64yrs
Elderly
>65yrs
Vitamin A
Retinol
1500ug –
Total Safe Intake.

Average intake from food =
700ug/day

Recommended maximum from supplements = 800ug/day
<1% <1% Chronic retinol toxicity: dry skin, headaches and lip cracking.
Cancer risk is increased by the long-term use of high-dose supplements.
Increased risk of osteoporotic fracture from high dietary or supplement intake especially if plasma retinol >2.5umol/l in older people.
High total intake may increase the risk of birth defects.
Alcohol excess, truncal obesity, renal failure or liver disease.
Review the use of long-term supplements including strong multivitamins and cod liver oil.
Avoid combination of cod liver oil and multivitamins.
Total supplement intake is best limited to <800ug/day.
Pregnancy or pre-pregnancy: avoid all retinol supplements unless proven to be deficient.
Prevalence of Excess:
Pl. Retinol  >2.5umol/l
13% 25%
Beta-carotene
7000ug
No lower blood limit Harmless yellow discolouration of the skin.
High dose supplements increase the risk of lung and other cancers in smokers.
Women, zinc deficient or low protein diet or hypothyroidism.
Avoid any use in smokers and those exposed to asbestos.
Plasma beta-carotene >2.5umol/l in 2.5% of women aged 19-24 yrs
Vitamin D
25ug
15% 10% Rarely hypercalcaemia causing fatigue and muscle pains. Hyperparathyroidism, TB, some cancers and sarcoidosis.
Vitamin E
540mg
(800IU)
Very rare Very rare Haemorrhagic stroke in elderly, male hypertensives.
Doses > 400IU/day can decrease the effects of vitamin K and increase the effect of warfarin.
Avoid high dose supplements in elderly hypertensives. 
Limit to <400IU/day in those on warfarin and monitor their INR.
Vitamin K
1000ug
Not assessed Not assessed Warfarin anticoagulant effect decreased. In those on anticoagulants avoid any use and use multivitamins cautiously.
Vitamin B12
2000ug
2% 7% Nil.  May induce potassium deficiency if severely anaemic. Correct potassium deficiency prior to correcting anaemia.
Folic acid
1000ug
Total Safe Intake 1500ug
5% 25% Corrects the anaemia but not the neurological features of vitamin B12 deficiency. 
Zinc absorption may be reduced by doses >1000ug/day.  Supplements might blunt the effect of chemotherapy.
Avoid in those with uncorrected vitamin B12 deficiency.
Avoid co-administration of zinc with high dose folate.
Seek advice if patient is taking a folate-antagonist drug.
Thiamin
100mg
1-2% 8% Rarely headache, tachycardia, nausea and insomnia. Uncertain, possibly the elderly or frail.
Riboflavin
40mg
Total Safe Intake
43mg
>50% >50% Harmless yellow colouration of urine. None known.
Niacin
17mg
Not assessed Not assessed Flushing, tingling, burning and itching in face and upper body, tachycardia, headache and abdominal pain.
Liver abnormalities, dry eyes and blurred vision at very high doses.
Flushing is less likely if dose <50mg, if taken after food or pre-treatment with aspirin.
Might aggravate gastritis.  
Monitor liver function tests if
receiving >500mg/day.
Nicotinamide
500mg
Total Safe Intake
560mg
Not assessed Not assessed Trials of supplements up to 3,000 mg/day appear well tolerated. Nicotinamide does not cause flushing or liver problems.
Vitamin B5
200mg
Total Safe Intake
210mg
Not assessed Not assessed Minor gastrointestinal symptoms might occur at doses >10g/day. None known.
Vitamin B6
10mg
<100mg is probably safe
10% Not assessed Intakes of >500mg/day can result in tingling and numbness in the limbs from a reversible sensory neuropathy after Persistent use. Possibly untreated other B vitamin deficiencies.
Peripheral neuropathy already affects 8% of adults >55 years.
Biotin
900ug
Total Safe Intake
970ug
Not assessed Not assessed Usually safe. None known.
Vitamin C
1000mg
4% 14% Diarrhoea is possible.
Increase in urinary oxalate.
A fall in serum copper is possible.
Pre-existing diarrhoea. 
History of oxalate-rich renal calculi.

* Safe Upper Levels and Guidance Levels are determined for an adult weighing 60kg.
** The prevalence of deficiency and excess are derived from the National Diet and Nutrition Surveys of British Adults (2003/4) and The Elderly (1995).  TSO London.

Safe Upper Levels and Guidance Levels for Minerals (2003)*
Nutrient
Safe Upper Levels or
Guidance Levels

Total Safe Intake from Food & Supplements

Prevalence** of Deficiency in the
British Population
Possible Adverse Effects 
Especially if Safe Upper Levels or Guidance Levels are  Exceeded
Additional Risk Factors for Toxicity and
Author’s Clinical Comments
Adults
19-64yrs
Elderly
>65yrs
Calcium
1.5g
5% 7% Diarrhoea from sorbitol excipient. Hypercalcaemia rarely occurs. Calcium intakes >2.4g/day (with milk and alkaline salts) can cause hypercalcaemia, renal failure and soft tissue calcification.
Kidney stone risk increased.
Reduced absorption of zinc.
Hypercalcaemia from cancer or vit. D sensitivity, see above.
Check dietary intake of dairy foods and antacids. 
Use with caution in those with  a history of kidney stones.
In elderly check serum calcium and renal function.
Phosphorus
250mg
(TSI 2400 mg)
None None Diarrhoea possible with doses >1000mg. Higher doses are tolerated if taken with calcium.
Magnesium
400mg
12% 20% Diarrhoea is the main adverse effect due to its osmotic effect.
Serious accumulation causes hypotension and collapse and could occur in those with reduced renal function.
Gastrointestinal hurry.
Caution if using a potassium-sparing diuretic or there is a reduced glomerular filtration rate, GFR.  Check serum magnesium if in doubt.
Potassium
3700mg
10% 25% Abdominal pain and vomiting due to gastritis or oesophagitis.
Serious accumulation can cause fatigue, heart failure arrhythmias and death.
Peptic ulcer or gastritis. 
Take supplements after food.
Check serum potassium if renal impairment, elderly or using a potassium-sparing diuretic. 
Iron
17mg
7% 10% Constipation, diarrhoea, abdominal pain and dark stools.  The iron excess of haemochromatosis results in fatigue, arthritis and diabetes.
Reduced zinc absorption.
Pre-existing constipation or diarrhoea.  Iron status should be checked periodically. 
Haemochromatosis is found in 0.6% of European populations.
Ensure adequate dietary zinc.
Zinc
25mg (TSI 42 mg)
4% 7% Abdominal pain, nausea and vomiting. 
Excess may cause copper deficiency (serum copper < 70 ug/dl) resulting in anaemia and neutropenia.
Abnormal cardiac function and mildly increased cholesterol.
Active peptic ulcer or gastritis.Poor dietary intake of copper due to a low-protein or gluten-free diet.
Check zinc and copper status periodically.
Copper
1mg

(TSI 10 mg)
Rare Rare Abdominal discomfort, nausea, vomiting and diarrhoea.
Very large excess may cause liver and renal failure and collapse.
Active peptic ulcer or gastritis.
Copper accumulation can develop in liver disease, Wilson’s disease and Indian Childhood Cirrhosis.
Iodine
500ug
(TSI 940 ug)
2% 3% High doses might rarely induce thyrotoxicosis or hypothyroidism.
Gastrointestinal irritation can occur with high doses.
Past level of intake determines the risk of toxicity; very low levels predispose to thyrotoxicosis and mildly low levels to hypothyroidism.  
Selenium
350ug
(TSI 450 ug)
Assessed but uncertain Assessed but uncertain Deformed nails, brittle hair, garlic breath and neurological problems.  Excretion is via the urine. Toxicity can occur with an intake > 910ug/day.
2 Brazil nuts provide ~53ug.  Check diet before prescribing.
Manganese
4mg
0 .5 mg if >50 yrs
(TSI 12.2 mg, 8.7 mg if > 65 yrs)
Uncertain Uncertain Excess manganese is neurotoxic.
Fatigue and Parkinson’s disease-like syndrome could rarely develop causing reduced mobility.
Industrial or environmental exposure can occur.
Elderly and those with liver disease are prone to toxicity.
Check diet before prescribing.
Chromium
10,000 ug
refers to trivalent chromium
Uncertain Uncertain There have been a few case reports of renal impairment in association with chromium picolinate use. If renal impairment or declin- ing function avoid picolinate. 
Chromium Glucose Tolerance Factor is probably safe.
Boron
6mg
(TSI 9.7 mg)
Non-essential Non-essential Male animal reproduction is adv- ersely affected by high exposure.
Excretion is via the urine.
Estimated maximum dietary intake in UK is 3.7mg/day
Nickel
260ug
See note in end
Column.
Non-essential Non-essential 7%-10% of the UK population have nickel sensitive dermatitis and can react to dietary sources.  Excretion is via the urine. Rarely included in supplements. Avoid completely in those with contact dermatitis or who are nickel sensitive
Tin
6.7mg
(TSI 13.0 mg)
Non-essential Non-essential Acute toxicity causes abdominal cramps, vomiting, diarrhoea, headaches and chills. Estimated maximum dietary intake in UK is 6.3mg/day.
Cobalt
1,400ug
Essential only as part of vitamin B12 Cardiotoxic effects and depressed iodine uptake are possible. Toxic effects with intakes of 6-8mg/day.  Estimated dietary  intake is 30ug/day
Vanadium
7.5mg
Non-essential Non-essential 50-125mg/day caused diarrhoea abdominal cramps and “green tongue” and fatigue. The EVM considered that vanadium could not be safely included in supplements.
Silicon
700mg
(TSI 760 mg)
Non-essential Non-essential No acute toxic effects.  Silica renal stones can develop in those taking magnesium trisilicate. Estimated UK maximum intake from food and water is 60mg/day.
Molybdenum
No figure for GL is given in the report.
Uncertain Uncertain Intakes >1mg/day could cause gout and raise uric acid level.
Excess can induce a deficiency of copper.  Excretion is via the urine.
Estimated UK maximum intake from food and water of 230ug/day is not considered to be a risk.

* Safe Upper Levels and Guidance Levels are determined for an adult weighing 60 kg.
** The prevalence of deficiency and excess are derived from the National Diet and Nutrition Surveys of British Adults (2003/4) and The Elderly (1995).  TSO London.



Copyright Dr. Alan Stewart M.B.B.S.M.R.C.P. (UK)M.F. Hom.
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