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Asia Pacific J Clin Nutr (1996) 5(3): 173-174

Determination of retinoic acid and retinol at physiological concentration by HPLC in Caucasians and Japanese women

Che Sam Lo¹ MD, PhD, ML Wahlqvist¹ MD,FRACP and Y Horie² PhD

1. Department of Medicine, Monash Medical Centre, Monash University, Melbourne, Australia
2. Nagoya Municipal Women's Junior College, Nagoya, Japan

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A sensitive, specific and simple method for simultaneous determination of retinoic acid and retinol in human serum by reverse phase HPLC with UV detector has been developed. Retinoic acid is measurable at physiological concentration in human serum by this method. There is no significant difference in serum retinoic acid level between Caucasian and Japanese subjects. However, the serum retinol level in Japanese women is significantly lower than that in Caucasian women

Key words: Retinoic acid, retinol, HPLC, Japanese, Caucasian

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Introduction

Retinoic acid and retinol status are related to immune function, differentiation of epithelial tissues, cancer and mortality among children^1-5. The public health and clinical measurement of fat soluble vitamins are assuming more importance⁶. In the present study we sought:

• to develop a simple HPLC method for the simultaneous assessment of retinoic acid and retinol status, applicable to clinical and population based studies; and
• to assess the status of these compounds in those with disparate food cultures

Subjects and methods

The study involved 28 apparently healthy Caucasians (14 men and 14 women from Melbourne, Australia) and 21 age matched healthy Japanese women from Nagoya, Japan (Table 1).

Table 1. The age, stature, body weight and body mass index (BMI) of Caucasian and Japanese. (Mean ± SEM)

Subjects	N	Sex	Age	Stature (cm)	Weight (kg)	BMI
Caucasian	14	M	49±3	176±2	74±2	24.0±0.7
			(37-64)	(169-182)	(56-89)	(17.8-28.9)
	14	F	49±2	163±1	63±3	23.8±1.4
			(40-62)	(154-170)	(39-94)	(14.5-35.3)
Japanese	21	F	50±1	155±1	54±1	22.5±0.6
			(41-59)	(143-161)	(43-64)	(16.8-28.1)

The reproducibility and recovery of retinoic acid and retinol are shown in Table 2. The coefficients of variation (CV) of retinoic acid and retinol for 6 replicate analysis of serum were 8.6% and 4.4% respectively. Known amounts of retinoic acid and retinol were added to real samples (serum) and recovery rate of retinoic acid was 98.2 ± 1.7%, with a range from 94-105%, and a CV of 4.1%. The recovery rate of retinol was 100.2 ± 1.9% with a range from 96-108% and CV of 4.5% (Table 2). Serum retinoic acid was not significantly different between Caucasian men and women, nor between Caucasian women and Japanese women. However, serum retinol was relatively lower in Japanese women than Caucasian women (Table 3).

Table 2. Reproducibility and recovery of retinoic acid and retinol (Mean ± SEM).   Reproducibility Recovery   N=6 N=6   CV% % Retinoic Acid 8.6 98.2 ± 1.7% Retinol 4.4 100.2 ± 1.9%

Discussion A sensitive, specific and simple method for simultaneous evaluation of retinoic acid and retinol in human serum by re 1000 verse phase HPLC with UV detection has been developed. Retinoic acid is measurable in physiological concentration in human serum by this method, at a molar concentration about 1.5% of that of retinol. It is known that food intake and homeostatic mechanisms influence serum retinol and both may account for the differences between Caucasians and Japanese women in this study7. However, despite the different food intake patterns of these two groups, retinoic acid concentrations are the same, which suggests that homeostatic control of serum retinoic acid is important. It is also clear that retinoic acid status does not necessarily parallel that of retinol.

Table 3. Retinoic acid and retinol levels in human serum (Mean ± SEM). e74 Subjects N Sex Retinoic Acid m mol/L Retinol m mol/L Caucasian 14 M 0.034± 0.004 2.39± 0.16   14 F 0.038± 0.005 2.57± 0.18** Japanese 21 F 0.031± 0.004 1.84± 0.08 N is the number of subjects; the mean ± SEM are shown; the significant difference between Caucasian and Japanese women is indicated by **p<0.001.

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Determination of retinoic acid and retinol at physiological concentration by HPLC

in Caucasians and Japanese women

Che Sam Lo, ML Wahlqvist and Y Horie

Asia Pacific Journal of Clinical Nutrition (1996) Volume 5, Number 3: 173-174

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References

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2. Ross AC, Hammerling UG. Retinoids and the immune system. In: Sporn MB, Roberts AB, Goodman DS, eds. The retinoids: biology, chemistry and medicine, second edition, New York: Raven Press, 1994: 521 -43.
3. Hong WK, Itri LM, Retinoids and human cancer. In: Sporn MB, Roberts AB, Goodman DS, ets. The retinoids: biology, chemistry and medicine, second edition. 1994. New York: Raven Press, 1994: 597-630.
4. Wolf G. Retinoids and carotenoids as inhibitors of carcinogenesis and inducers of cell-cell communication. Nutr Rev 1993; 50: 270-74.
5. Fawzi WW, Herrera MG, Willett WC, et al. Dietary vitamin A intake and the risk of mortality among children. Am J Clin Nutr 1994; 59: 401 -08.
6. De Leenheer AP, Neilis HJ, Lambert W, Bauwens RM, Chromatography of fat soluble vitamins in clinical chemistry. J Chromatograph 1988; 429: 3-58.
7. Rabucco LB, Rutishauser IHE, Wahlqvist ML. Dietary and plasma retinol and betacarotene relationships in Filipinos, non-Aboriginal and Aboriginal Australians. Ecology of Food and Nutrition; 1991; 26:97-108

Copyright © 1996 [Asia Pacific Journal of Clinical Nutrition]. All rights reserved.
Revised: January 19, 1999 .
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