Nutritional Evaluation of Serum Lactate Dehydrogenase Levels in Humans

〔541〕

Masahide Imaki, Tamotsu Miyoshi and Takeshi Yoshimura

Department of Public Health, School of Medicine, University of Tokushima, Tokushima

INTRODUCTION Measurements of the activity and isozyme pattern of serum lactate dehydrogenase (LDH) have been widely used as liver function tests. The serum LDH activity is often increased in heart or liver diseases1,2), and the changes in the serum LDH isozyme pattern reflect characteristic disturbances in various organs. Serum gamma-glutamyl transpeptidase is used as an index of alcohol consumption3) in healthy people, but serum LDH activity and the LDH isozyme pattern are not used as health indices. Since the serum LDH activity and LDH isozyme pattern would be easy to measure in screening tests, we examined the availability of use of these parameters as health indices by studies on their changes with nutrient intake.

METHODS

This study consisted of two parts, an epidemiological study and a laboratory study. Epidemiological study: A total of 102 volunteers were examined. The volunteers included 92 men Table 1 Characteristics of the subjects in the and 10 women between the ages of 20 and 28 who had epidemiological study. no past history of liver trouble. Table 1 shows data on the physical characteristics of the subjects. Blood was usually collected from the cubital vein of subjects after over-night fasting. The serum was separated, and the serum LDH activity and percentages of LDH isozymes were measured on the same day. Nnmber of subjects: 102 (92men, 10women), Rohrer Serum LDH activity was determined by a UV index: (Weight/Right3)×107.

Table 2 Experimental design in the laboratory study.

Numberof volunteers: 4men. Experimentalperiod: 2ldays. *: For details, see Reference (12). 〔542〕 JAPANESE JOURNAL OF HYGIENE method4) with an LDH-UV Test kit (Wako Pure Chemical, Industries, Ltd.). Serum LDH isozymes were separated by electrophoresis on agarose film5). All food eaten by the subjects in a 2-day period before the test was weighed, and the intakes of energy, protein, fat, sugar, animal protein, animal fat, vegetable protein and vegetable fat were calculated from Standard Tables of Food Composition in Japan (3rd revised edition). Data were processed with a PC-8800 personal computer. Laboratory study: The experiment lasted 3 weeks. The subjects examined were four healthy male university students. The personal characteristics of the volunteers are shown in Table 2. The subjects lived in the metabolic ward of our laboratory throughout the study, and continued their normal daily routine. The composition of the experimental diet, which was rather low in protein (40-50g of protein per day) is shown in Table 2. The volunteers were given this diet for 21 days, and their serum LDH activity and percentages of serum LDH isozymes were measured at intervals.

RESULTS

1) Epidemiological study

Table 3 Nutrient intakes, serum total LDH activity, and percentages of serum LDH isozymes.

Table 4 The correlation coefficients between serum total LDH activity, percentage of LDH isozyme and nutrient intakes. VOL. 39, NO. 2, June 1984 〔543〕

Table 3 shows the dietary intakes of nutrients, the activity of serum total LDH, and the percentages of serum LDH isozyme fractions in the 102 subjects. As can be seen in Table 4, there was no significant correlation between the serum total LDH activity and the dietary intake of nutrients in the 102 subjects. High inverse correlations were observed between the percentage of the fourth isozyme fraction of serum lactate dehydrogenase (LDH-4) and the protein intake (r=-0.468, p<0.01), between the percentage of the fifth isozyme fraction of serum lactate dehydrogenase (LDH-5) and the protein intake (r=-0.486, p<0.01), between the percentage of LDH-4 and the fat intake, and between the percentage of LDH-5 and the protein intake/kg of body weight. The percentages of LDH-2 and LDH-3 were not correlated with the dietary intakes of nutrients. 2) Laboratory study Table 5 shows the changes in the percentages of LDH-4 and LDH-5 as a result of the experimental diet during the 21-day period. Both showed a tendency to increase as a result of the rather low protein

diet. The percentage of LDH-5 increased significantly (p<0.05) from 5.3±1.7 to 10.6±2.6% after 21 days , while the percentage of LDH-4 increased from 8.5±2.1 to 10 .9±1.7%. The serum total LDH activity and the percentages of other isozymes showed no significant changes.

DISCUSSION

Serum lactate dehydrogenase (LDH) activity and its percentage isozyme pattern are often used as indicators of liver or heart disease. However, in this study we examined their availability as indices of the nutritional status of healthy people. In the epidemiological study, all the subjects examined were young . And their dietary intakes of energy and protein exceeded the basic daily nutritional requirements. They were well-nourished people in apparent good health. Their percentage distribution of serum LDH isozymes was similar to that reported by Nakayama et al.6). There are many reports that the serum total LDH activity in healthy persons shows scarcely any change during starvation, before and after meals, or with the quality of food eaten7～10) . In this study, we also found no significant correlation between the serum total LDH activity and the dietary intake of nutrients. The serum total LDH activity of the four volunteers also did not change during 21 days on a rather low protein diet. However, high inverse correlations were observed between the percentage of LDH-4 and protein intake, the percentage of LDH-4 and fat intake, the percentage of LDH-5 and protein intake, and the percentage of LDH-5 and protein intake/kg of body weight. In the laboratory study , the percentages of LDH-4 and LDH-5 increased with a decrease in dietary protein intake. Marshall et al.9~ reported that the percentages of LDH-4 and LDH-5 increased during intakes of experimental diets containing 60% sugar. Our laboratory study confirms the results of our epidemiological study. The respective serum LDH isozymes originate from different organs, and because the LDH-4 and

Table 5 Changes of percentages of serum LDH isozyme with experimental diet. 〔544〕 JAPANESE JOURNAL OF HYGIENE

LDH-5 contents of the liver are high, it is supposed that these isozymes pass from the liver into the blood stream due to slight fatty digeneration11). The percentages of these two isozymes are much lower than those of other isozymes. Changes in the percentages of their isozymes did not seem to be reflected in changes in the serum total LDH activity. Our results show that the percentages of LDH-4 and LDH-5 can be used as indicators of protein or fat intake. In general, the nutritional status of a subject depends on his social, economic, personal and family background. Use of enzymes to evaluate the adequacy of nutrient intake would be very useful in health guidance. In this study, we found that measurements of the percentages of LDH-4 and LDH-5 isozymes, which are also used as liver function tests, could be used for evaluating the levels of protein and fat intake.

SUMMARY The effects of dietary intake of nutrients on the activity and isozyme pattern of serum lactate dehydrogenase (LDH) were examined. In an epidemiological study, no significant correlations were found between the serum total LDH activity and dietary intakes of nutrients in healthy young volunteero (92 men , 10 women). However, high inverse correlations were found between the percentage of the fourth isozyme of serum lactate dehydrogenase (LDH-4) and protein intake, between the percentage of the fifth isozyme of serum lactate dehydrogenase (LDH-5) and protein intake, between the percentage of LDH-4 and fat intake , and between the percentage of LDH-5 and protein intake/kg of body weight. In a laboratory study, the percentages of LDH-4 and LDH-5 in four volunteers on a relatively low protein diet (40-50g of protein per day) tended to increase, in particular, the percentage of LDH-5 increased significantly from 5.3±1.7 to 10.6±2.6% (p<0.05).

REFERENCES 1) Hill, B. and Levi, C.: Elevation of serum components in neoplastic diseases, Cancer Res., 14, 513-518 (1954). 2) Wroblewski, F. and Gregory, K. F.: Lactic dehydrogenase isozymes and their distribution in normal tissues and plasma and in disease states, Ann. N. Y. Acad. Sci., 94, 912-918 (1961). 3) Laure, P. M., Warent, J. M., Peqignot, G., Eveline, E., Claude, J. R. and Schwartz, D.: Alcohol consumption in a healthy population, J. Am. Med. Assoc., 245, 1748-1751 (1981). 4) Wroblewski, F. and La Due, S. J.: Lactic dehydrogenase activity in blood, Proc. Soc. Exp. Biol. Med., 90, 210 -215 (1955). 5) Opher, A. W.: A rapid electrophoretic method for the determination of the isoenzymes of serum lactate dehydrogenase, Clin. Chem., 12, 308-313 (1966). 6) Nakayama, T. and Kitamura, M.: LDH (lactate dehydrogenase), Rinsho Biyhori (Jpn. J. Clin. Path), 43, 8-9 (1981). 7) Meyer, F. L., Mattox, H. and Bolick, M.: Metabolic changes after tests meals with different carbohydrate : blood levels of pyruvic acid, glucose, and lactic dehydrogenase, Am. J. Clin. Nutr., 24, 615-621 (1971). 8) Katchman, B. J. and Zipf, E.: Correlation between triglycerides and glutamic-pyruvic transaminase in men on high-fat diets, Clin. Chem., 16, 118-123 (1970). 9) Marshall, W.: Changes in lactate dehydrogenase, LDH isozymes, lactate, and pyruvate as a results of feeding low fat diets to healthy men and woman, Metabolism, 25, 169-178 (1976). 10) Aoki, R.: LDH and its isozyme, Nihon Rinsho (Jpn. J. Clin. Med.), 34, 2462-2472 (1976). 11) Yashiro, M., Hoshino, T, and Kimura, S.: Effect of voluntary exercise and dietary protein levels on the activity of serum glutamic pyruvic transaminase and the morphorogical picture of liver in mice, J. Nutr. Sci. Vitaminol., 26, 71-76 (1980). 12) The Science and Technology Agency: Japanese Food Composition Table (3rd ed.), the Finance Ministry Printing Office, Tokyo (1963). VOL. 39, NO. 2, June 1984 〔545〕

人血清Lactate Dehydrogenase活性値レベルの

栄養学的評価

徳島大学医学部公衆衛生学教室

今木雅英・三好保・吉村武

この研究において,血清Lactate Dehydrogenase活性値,及びアイソザイムパターンに関して,栄養素摂取量の影響を調べた。疫学的研究では,若い健康な対象者(男92名,女10名)において,栄養素摂取量と血清総LDH活性値は有意な関係はなかった。高い負の相関が,LDH-4分画比と蛋白質,脂質摂取量,LDH-5分画比と蛋白質,蛋白質/kgに認められた。実験的な研究において,4人の被験者に21日間,蛋白質摂取量を栄養所要量以下(40-50g)に制限すると,特にLDH -5分画比が5 .3±1.7%から10.6±2.6%に有意に上昇した。

Key words: Nutritional evaluation, Serum LDH activity, Low protein diet, LDH isozyme 栄養学的評価,血清LDH活性値,低蛋白質食,LDHアイソザイム

(受付1983年10月24日)