Serum Ascorbic Acid, Vitamin A and Beta-Carotene Levels in Iranian Patients with Cancer
L. Mireskandari PharmD* , S. A. Ziai PharmD*, P. Salehian MD**, I. Noormohammadi PhD*** and M. Mahmoudian PhD*
*Department of Pharmacology, **Department of Pathology, ***Department of Biochemistry, Iran University of Medical Sciences, Tehran, Iran.
Background-Free radicals seem to be
implicated in the genesis of a variety of pathological
conditions, including inflammation and cancer. A belief
has emerged among scientists that diet including vitamin
A and C might influence the development of cancer in
humans.
Objective-To reassess the validity of such
hypothesis, serum level of vitamin A, ß-carotene
and vitamin C were measured in a group of patients
suffering from different types of cancer.
Methods-Two groups (each comprised of 30
cases) of diagnosed cancer patients were compared with
healthy volunteers. Serum vitamin A, C and
ß-carotene were measured.
Results-The mean serum levels of vitamin
A, ß-carotene and vitamin C in patients with
cancer, were significantly (p<0.001) lower than those
in healthy individuals.
Conclusion-Our limited results confirm the
notion that cancer patients have low levels of some
vitamins which may be due to cancer, chemotherapy, or
malnutrition and supplement of vitamins may have a
benifical effect.
Keywords • Ascorbic acid • ß-carotene • Vitamin A • cancer
Introduction
Free radicals seem to be implicated in the genesis of a variety of pathological conditions, including inflammation and cancer.1 A number of enzymatic and non-enzymatic mechanisms have evolved to protect living organisms against oxidative injuries. Non-enzymatic defense mechanisms are provided by antioxidant molecules, which act as reducing agents or as free radical scavengers.
Some 20 years ago, there began to emerge a belief among scientists that diet might have an influence on development of human cancer. Since this subject has received much attention from both consumers and scientists.2,3
To reassess the validity of this hypothesis in our patients with cancer, in a case-control study, we tried to determine serum level of vitamin A, ß-carotene and vitamin C in a group of patients suffering from different types of cancer at different stages of the disease and compared the results obtained in healthy normal individuals.
Material and Methods
Thirty patients (23 female and 7 male) with diagnosed cancer were compared with 29 (21 female and 8 males) healthy individuals for serum vitamin A and ß-carotene. Twenty-one had breast cancer and 9 suffered other cancer types. Subjects taking vitamin supplements were excluded. Thirty (22 male and 8 female) other patients with cancer were compared with 31(20 male and 11 female) healthy subjects for serum vitamin C.
To determine the serum levels of vitamin A, ß-carotene and vitamin C, blood samples were taken and sera were separated within 2 hours of blood withdrawal and stored in tubes protected from light at -20 °C until analysis. The serum ß-carotene and vitamin A levels were determined by spectrophotometry according to Neeld-Pearson procedure.4 For determination of serum vitamin C level, sera were collected and analyzed immediately or not later than 30 minutes after sample collection. Vitamin C level was determined photometrically as described by McCormick et al.5
Results
The mean serum levels of vitamin A, ß-carotene and vitamin C for the patients and healthy individuals are depcited in figure 1. The level of vitamin A and ß-carotene in the cancer group were divided into two subgroups; patients having breast cancer (n=21) and patients having other types of cancer (n=9). The mean and standard deviation of vitamin A in breast cancer and other types of cancer were 16.91 (+8.27) µg/dl and 18.32 (+6.61) µg/dl respectively while ß-carotene was 151.90 (+44.34) µg/dl and 164.77 (41.23) µg/dl respectively. The levels did not differ significantly from each other but were significantly lower than serum values in healthy individuals.
Discussion
The mechanisms through which retinoids influence carcinogenesis have been well documented.6,7 These mechanisms have been hypothesized to include controlling cell differentiation and changes in membrane receptors that may influence cell-cell interactions, cell adhesion, and cell membrane permeability.6,7 Our study showed low vitamin A levels in cancerous patients. ß-carotene acts as a powerful quencher of singlet oxygenated scavenger of free radicals.8 It has been hypothesized that ß-carotene might be beneficial through local conversion to retinol at tissue level.9,10
Another postulated mechanism of action for ß-carotene is its immunomodulatory effects.11 A large number of observational epidemiological studies have investigated the association between ß-carotene intake and cancer risk in humans.
An important water-soluble, chain-breaking antioxidant is ascorbic acid (vitamin C), which reacts directly with superoxide singlet oxygen and regenerates tocopherol from the tocopheroxy radical.12,13 Vitamin C also affects the immune system,14 and could thus enhance tumor immune surveillance in promotion and progression of the cancer.2 Finally, studies have reported effects of vitamin C on liver enzymes which are responsible for detoxification and transformation of carcino-gens 2.
Acknowledgement
The authors would like to thank Dr. Seyed Hamid Mirkhany, the head and staff of Institude of Cancer, Imam Khomeini Hospital, Tehran University of Medical Sciences, Dr. Yavari of Department of Pharmacology, Iran University of Medical Sciences, and the staff of Kavosh Clinical Laboratory, Tehran, for their assistance.
References