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You must read and accept the disclaimer to use this site.

Possible Hazards of Supplements including Vitamins
Found in a variety of sources
Use the find command on your computer to search items you consider taking. Note this is a list that includes speculation by various authors and many of these hazards may never have been observed clinically.

Post-2000 reports/comments/questions:

Tooth erosion concerns from chewing vitamin C tablets

Prior to 2000
1. "Total Nutrition: The Only Guide You Will Ever Need", V. Herbert and G. J. Subak-
Sharpe, St. Martin's Press, NY, 1995. See pages 101-104.
2. August 1998, Berkeley Wellness Letter, Echinacea - "benefits unproven. Little known about
toxicity. Prescribed in Germany for colds and flu. Little known about toxicity." It is speculated
that Echinacea may cause allergies or immune hyperactivity.
3. Complete Guide to Vitamins, Minerals, and Supplements, H. Winter Griffith, MD, Fisher
Books, AZ, 1988
B-vitamins
B1-
Precautions: Don't take if you are allergic
Adverse reactions: (rare) Skin rash or wheezing
B2-
Precautions: Don't take if you are allergic or have kidney failure
Adverse reactions:
B3-
Precautions: Don't take if you have allergy to vitamin B3, impaired liver function, active peptic
ulcer, diabetes, gout, gallbladder disease
Adverse reactions: diarrhea, abdominal pain, faintness, headache, jaundice, nausea, skin dryness,
vomiting
B5-
Precautions: Don't take if you are allergic or are taking levodopa for Parkinson's disease
Adverse reactions: none
B6-
Precautions: Don't take if you are allergic or are taking levodopa for Parkinson's disease
Adverse reactions: none
B9 -
Precautions: Don't take if you have pernicious anemia, or take anticonvulsant medicine
Adverse reactions: diarrhea, fever, skin rash
B12 -
Precautions: don't take if you are allergic to vitamin B12 or have Leber's disease.
Adverse reactions: Diarrhea (rare)
Vitamin C
Precautions: Don't take if you are allergic or have gout, kidney stones, or sickle cell anemia
Adverse reactions: anemia, flushed face, headache, increased urination, lower abdominal cramps,
diarrhea, nausea, vomiting
Vitamin E
Precautions: Don't take if you are allergic to vitamin E, liver disease, cystic fibrosis, overactive
thyroid, bleeding or clotting problems, iron-deficiency anemia
Adverse reactions: (all rare) Abdominal pain, breast enlargement, diarrhea, dizziness, flu-like
symptoms, headache, nausea, fatigue, blurred vision.
Zinc-
Precautions: Don't take if you have ulcers
Adverse reactions: abdominal pain, abnormal bleeding, burning pain in upper chest relieved by
food or antacid, mild diarrhea, nausea, vomiting
Alpha-lipoic acid -is a normal metabolic intermediate
" Insulin resistance of skeletal muscle glucose uptake is a prominent feature of Type II diabetes
(NIDDM); therefore, pharmacological intervention should aim to improve insulin sensitivity.
Thioctic acid (TA, which is the same as lipoic acid), a naturally occurring compound, was shown
to enhance glucose utilization in various experimental models after acute and chronic
administration. .... As the present investigation was an uncontrolled pilot trial, the encouraging
results call for controlled studies to further elucidate the clinical relevance of the findings and the
mode of action of this compound." Jacob S; Henriksen EJ; Tritschler HJ; Augustin HJ; Dietze
GJ, "Improvement of insulin-stimulated glucose-disposal in type 2 diabetes after repeated
parenteral administration of thioctic acid" [note thioctic acid is lipoic acid], Exp Clin Endocrinol
Diabetes 1996;104(3):284-8
" To evaluate the efficacy and safety of oral treatment with the antioxidant alpha-lipoic acid (ALA)
in NIDDM patients with cardiac autonomic neuropathy (CAN), assessed by heart rate variability.
(HRV). ..In a randomized, double-blind placebo-controlled multicenter trial ... patients ...were
randomly assigned to treatment with daily oral dose of 800 mg ALA (n = 39) or placebo (n = 34)
for 4 months... Seventeen patients dropped out of the study (ALA n = 10; placebo n = 7). .. These
findings suggest that treatment with ALA using a well-tolerated oral dose of 800 mg/day for 4
months may slightly improve ...patients" Ziegler D; Schatz H; Conrad F; Gries FA; Ulrich H;
Reichel G, "Effects of treatment with the antioxidant alpha-lipoic acid on cardiac autonomic
neuropathy in NIDDM patients. A 4-month randomized controlled multicenter trial (DEKAN
Study). Deutsche Kardiale Autonome Neuropathie", Diabetes Care 1997 Mar;20(3):369-73
 
Conjugated linolenic acids - is found in large quantities in whole milk.
" One three-month preliminary study with 20 healthy volunteers showed that 3.6 grams of CLA a
day decreased body fat from 21.3% to 17%. Atkinson described a longer study with more
subjects which he is undertaking to determine if this reduction in fat is repeatable" INFORM, Vol
9 pg 69-72 (1998), "Scientific Forum Explores CLA Knowledge"
N-Acetyl-Carnitine - is a normal metabolic intermediate
" A rapidly growing body of evidence suggests that the apparent age-related deficits in
mitochondrial functtion can be slowed or reversed by acetyl-L-carnitine (ALCAR), a normal
component of the inner mitochondrial membrane...ALCAR has been shown to reverse the age-
related decrease in [important mitochondrial functions]...Chronic administration of this compound
to rats is associated with a reduction in the accumulation of lipofuscin...It has also been shown to
attenuate the age-related decrements in active avoidance learning" Shigenaga, MK and Ames,
BN, "Oxidants and mitochondrial decay in aging", pg 63-106, in Natural Oxidants in Human
Health and Disease, B. Frei, ed., Academic Press, NY, 1994
" A 1-year, double-blind, placebo-controlled, randomized, parallel-group study compared the
efficacy and safety of acetyl-L-carnitine hydrochloride (ALCAR) with placebo in patients with
probable Alzheimer's disease (AD). Subjects with mild to moderate probable AD, aged 50 or
older, were treated with 3 g/day of ALCAR or placebo (1 g tid) for 12 months. Four hundred
thirty-one patients entered the study, and 83% completed 1 year of treatment. ... Overall, both
ALCAR- and placebo-treated patients declined at the same rate on all primary and most
secondary measures during the trial. In a subanalysis by age that compared early-onset patients
(aged 65 years or younger at study entry) with late-onset patients (older than 66 at study entry),
we found a trend for early-onset patients on ALCAR to decline more slowly than early-onset AD
patients on placebo on both primary endpoints.... The study suggests that a subgroup of AD
patients aged 65 or younger may benefit from treatment with ALCAR whereas older individuals
might do more poorly..." "A 1-year multicenter placebo-controlled study of
acetyl-L-carnitine in patients with Alzheimer's disease", Thal LJ;
Carta A; Clarke WR; Ferris SH; Friedland RP; Petersen RC;
Pettegrew JW; Pfeiffer E; Raskind MA; Sano M; Tuszynski MH;
Woolson RF, Neurology 1996 Sep;47(3):705-11