Table 3.

Potential toxic effects associated with select vitamin supplements*

Vitamin	Potential toxic effects associated with supplement
Vitamin A (retinol)	Hepatotoxic effects, visual changes, hair and skin changes, teratogenic effects at intake>1000-1500 IU/day; potential increased risk of hip fracture at intake>5000 IU/day
Beta carotene (provitamin A)	Risk of lung cancer among smokers and people with asbestosis at intake>3000 IU/day; yellowing of skin, diarrhea and arthralgias
Vitamin C (ascorbic acid)	Diarrhea, gastric upset at intake >2000mg/day
Vitamin D	Soft tissue calcification or hypercalcemia at intake >2000 IU/day
Vitamin E	Nausea, vomiting, diarrhoea, possible antiplatelet effects, headache fatigue and blurred vision at intake > 800 IU/day
Vitamin B6 (pyridoxine)	Sensory neuropathy, ataxia if regular intake>200 mg/day
Vitamin B (cyanocobalamin)	No upper limit known.
Niacin (vitamin B)	Vasodilatation, gastrointestinal upset, hyperglycemia, potential interactions with statins, antihypertensive drugs; hepatotoxic effects may occur at intake>3000 mg/day