While those who smoke or have certain ailments may benefit from exceeding the RDA of some vitamins, high levels of certain vitamins can be toxic in healthy adults.
Since it's almost impossible to eat enough food for vitamin toxicity to occur, the likeliest way too get too much of certain vitamins is by taking excessive quantities of supplements.
What is Considered Excessive?
Currently there is no clear definition of what constitutes excessive when it comes to vitamins. However, the general consensus is that excessive is considered to be several times the RDA (Recommended Dietary Allowance) or more than the Tolerable Upper Intake Level (UL) set by the Institute of Medicine.
Which Vitamins are Toxic in Large Doses?
Vitamin A: The UL of vitamin A for adults is 3,000 mcg (10,000 IU). Anything over that and the following may occur: liver damage, reduced bone density which may result in osteoporosis, and central nervous system disorders. Also, pregnant women who take more than the UL doubles the risk of giving birth to a child with birth defects. Vitamin A taken in great amounts over a short period of time can result in: nausea, vomiting, headache, abnormal vision, constipation, loss of appetite, and low-grade fever.
Vitamin B6: Long-term use of more than 100 mg of vitamin B6 may result in damaged nerves in the arms, legs, hands, and feet. It is not clear whether this damage is reversible once supplementation has stopped.
Vitamin C: Healthy adult non-smokers who take more 1,000 mg or more of vitamin C may experience stomach upset, diarrhea or constipation.
Vitamin D: The UL of vitamin D is 50 mcg (2,000 IU) for adults. Long-term megadoses higher than the UL can result in: kidney damage, heart damage, nausea, vomiting, loss of appetite, weight loss, muscle weakness, mental confusion, and elevated levels of calcium in the blood.
Large doses of vitamin D taken over a short period of time typically does not cause toxicity as excess vitamin D is stored and used by the body as needed.
Vitamin E: Since vitamin E acts as an anticoagulant and may increase the risk of bleeding problems, the Food and Nutrition Board of the Institute of Medicine recommends the UL of vitamin E to be 1,000 mg (1,500 IU). Also, excessive levels of vitamin E may cause dizziness or an upset stomach.
To avoid vitamin toxicity, healthy adults should choose quality supplements that contain no more than the RDA for any ingredient and only take the amount listed on the label. Combining a daily multivitamin with a healthy diet can ensure that the body is getting all the vitamins and nutrients it needs without risking the health effects of vitamin toxicity.
The copyright of the article Effects of Excessive Vitamin Intake in Vitamins & Minerals is owned by Jennifer Murray. Permission to republish Effects of Excessive Vitamin Intake in print or online must be granted by the author in writing.
Hello, My name is Shannon and I started taking a myriad of vitamins
and supplements for fibromyagia/chronic fatigue and the massive dose of
vitamins caused me to go into anaphylactic shock a number of times. As a
result, I now have nervous system damage, and an auto-immune disease. I
wish there was some way I could reverse what I've done, but I now suffer
from permanent damage, causing debilitating and chronic symptoms.
Aug 17, 2008 10:31 AM
Jennifer Murray :
Hi Shannon,
Thank you for commenting, and I want you to know I
am really sorry to hear about your situation.
Aug 26, 2008 8:51 PM
Guest
:
I took the following supplements for a month and then was very sick for 2
days without any noticable symptoms except sleep and severe lower back
pain. It's been a month later since I was sick and stop taking these
supplements and I now have severe pain in my groin and lower back. I've
been to the ER and my family dr but they have found nothing. I've been
treated with a high dose of antiboitics for 17 days without improvement. Dr
says what I took is not the cause of my illness. Next is to do a CT scan of
liver and gall blader. Did supplements damage my liver? George
L_GLUSINE 500mg Once a day Vitamine C 1000-4000mg Once a day Vitamine E 400-800 IU Once a day Niacinamide 250mg every 3 hrs Magnesium 200-400mg Once a day Manganese 5-50mg Once a day Copper 2mg Once a day Zinc 15-25mg Once a day Boron 6mg Once
a day Selenium 100-250mg Once a day
Sep 9, 2008 5:28 PM
Guest
:
For those of you that are afraid of taking too much of something I highly
recommend: Centrum. It's a multivitamin pill that has all of the vitamins
rolled into one. Keep in mind that as it is stated 10,000 IU is maximum.
Centrum only has 3500 IU. It's complete safe, in fact my doctor recommended
it to me this past physical only a few weeks ago and to be honest I never
felt better.
I have an anxiety disorder on top of panic issues,
and to top the cake, I am somewhat overweight (not classified as obese,
just 6'0 at 245 lbs when I should be 200). I am constantly tired and feel
as though I am irritable. I also have psoriasis on my scalp and to be
honest after starting to take vitamins all of that stopped happening. It
cleared up. I really recommend it, especially the Carb Assist version of
Centrum, it really doesn't make you overly hungry like most adult
multivitamins do. Try it out, you won't be disappointed!
Mar 9, 2009 10:30 AM
Guest
:
Jennifer,
I have a habit of eating a healthy dose of fruits and
vegs in the morning (which include about 100 g of baby carrots). I recently
looked up the dietary information about carrots and found that it contains
more than 13000 IU of vitamin A. Does it matter if the source of vitamin is
natural or pills when it comes to Overdose?
Aug 7, 2008
