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Calcium Absorption from the Ingestion of Coral-Derived Calcium by Humans.
Kunihiko ISHITANI, Eiko ITAKURA Shiro GOTO and Takatoshi ESASHI 1 Higashi Sapporo Hospital, Sapporo 003-8585, Japan 1 Formerly, Tokyo University of Agriculture, Ichikawa 272-0035, Japan 3 Division of Applied Food Research, The National Institute of Health and Nutrition, Tokyo 162-8636, Japan (Received September 20. 1998) Summary Recent dietary life involves frequent opportunities for
the ingestion of purified, processed food products and preserved
foods, and it has been pointed out that the current dietary mineral
intake strongly tends toward nutritional imbalance. The Ryukyu Islands
yield coral which contains calcium and magnesium in a content ratio
of about 2 to I, with their approximate contents of 20 and 10%,
respectively. In this report, the calcium absorption from the ingestion
of crackers into which the coral powder was incorporated (coral-added
crackers) and that from ingestion of calcium carbonate-added crackers
was comparatively assessed. Twelve healthy adult volunteers (6 men
and 6 women) ingested coral-added crackers (calcium content: 525
mg) and calcium carbonate-added crackers (ditto) once each alternately
on a cross-over design with a wash-out period of 3 d between the
regimens. The study also included controls receiving neither cracker.
The degree of intestinal absorption of calcium from coral-added
crackers and that from calcium carbonate-added crackers was evaluated
in terms of increment in urinary calcium excretion per dL of glomerular
filtrate (GF) (difference between coral calcium and calcium carbonate)
and increase in urinary calcium excretion per milligram creatinine
(difference from control value). The increment in urinary calcium
excretion per dL of GF during the latter half of the observation
period after the ingestion of coral-added crackers was significantly
greater than that during the latter half of the observation period
after ingestion of calcium carbonate-added crackers (p =0.039, paired
t-test). A significant difference (from control value) in the increase
of urinary calcium excretion per milligram creatinine was also observed
(p = 0.0008). The present data, though from a relatively few study
subjects, suggest that the calcium of coral origin is better absorbed
from the intestine than calcium of calcium carbonate origin on the
average. A therapeutic or prophylactic approach to osteoporosis, or to suppression of decrease in bone mass, is calcium supplementation. The underlying mechanism is generally thought to consist in the suppression of parathyroid hormone secretion (2). Recently, stress is laid particularly on the importance of a well-balanced supply of calcium and magnesium rather than simple calcium intake (3). In their epidemiological study on the relationship of cardiac disorders to calcium/magnesium intake ratio in 1940, Karppanen et al (4) pointed out that the number of patients with cardiac disorder was prone to increase with rising calcium/magnesium ratio. Additionally, cardiac disorders were found to be of the highest in incidence in Finland where the intake ratio exceeded 4: 1. It has also been demonstrated by Seelig et al (5) in a balance test with a daily magnesium intake of350mg and a progressively increasing daily calcium intake of 200 to 1,400 mg that urinary magnesium excretion increased with increasing calcium intake, leading eventually to a negative balance with excessive magnesium excretion over its actual intake. The nutritional requirement for calcium is 600 mg a day and the recommended daily magnesium intake is 300mg in Japan . It may thus be said that a calcium:magnesium intake ratio of 2: 1 is advisable for Japanese (6). Ryukyuan coral is a dietary material approved as a food additive that contains calcium and magnesium in an approximate ratio of 2: 1, with their contents of 20 and 10%, respectively. Under the view that it is justified to add this foodstuff to the so-called nutritionally well-balanced foods which satisfy the mineral balance, we incorporated coral powder into inexpensive, light, tasty crackers. This foodstuff was incorporated into crackers to permit a well-balanced mineral intake of about half the daily requirements of .calcium and magnesium (i.e., 300 mg calcium and 150 fig magnesium) by the daily ingestion of 4 crackers (per box) as a snack. This study was undertaken to evaluate in humans whether mean intestinal absorption of coral-derived calcium incorporated into crackers (h~reinafter referred to as coral-added crackers) might be comparable or even superior to mean intestinal absorption of calcium carbonate-derived calcium in crackers. METHODS Subjects. Twelve normal subjects (6 men and 6 women; their ages, body weights and heights shown in Table I) participated in the study after giving written informed consent. The study was designed in accordance with the spirit of the De- claraltion of Helsinki (adopted in 1964; as amended in 1989) (7) and conducted after review ,l!1d approval by the Higashi Sapporo Hospital Institutional Review Board. None of the subjects had a history of bone disease, peptic ulcer, enterectomy, regional enteritis, malabsorption, nephrolithiasis, liver cirrhosis, or renal disorder. The subjects had not taken calcium supplements or vitamin D preparations, nor received anticonvulsants, diuretics, adrenocorticosteroids, estrogens or any other drugs .that could affect calcium metabolism during the month preceding the start of the study. Methods. The subjects were divided into two groups; subjects of one group ingested coral-added crackers first (group A) and those of the other group ingested calcium carbonate-added crackers first (group B). After a subsequent 3-d wash-out period, the groups received the study regimens on a cross-over design. An additional group (group C) served as a control not ingesting crackers. In order to sharpen calcium absorption, all study subjects were so instructed as to adhere to a daily diet restricted in calcium (300 mg/d, corresponding to half the dietary allowance), magnesium (150mg/d, corresponding to half the aimed intake) and sodium (2.3 g/d, corresponding to half the dietary allowance) beginning 2 d prior to the start of study regimens. Each 12-g piece of coral-added cracker contained 75 mg of calcium and 36 mg of magnesium. Calcium and magnesium contents of a 12-g calcium carbonate-added cracker were 75 and 6mg, respectively. Each subject ingested seven pieces of either cracker each time in this study since, according to Harvey et al (8), oral ingestion of 500 mg of calcium suffices for adequate evaluation of intestinal calcium absorption by measurements of urinary calcium excretion. The calcium intake and magnesium intake after the ingestion of 7 coral:. added crackers were calculated to be 525 and 252 mg, respectively, and those after ingestion of 7 calcium carbonate-added crackers to be 525 and 42 mg, respectively. Controls (group C) did not ingest either cracker at all. During
each phase ofthe study, all subjects fasted from 8:00p.m. of the
preceding day, but were allowed to drink 300mL of distilled water
at 8:00 and 11 :00 p.m. of that day and 600 mL of distilled water
at 6:00 a.m. of the test day. Procedure for evaluation of calcium absorption. In this study, the calcium absorption from the intestinal tract was evaluated on the basis of urinary calcium excretion as reported by Harvey et al (8), Nicar and Pak (9), Pak et al (10), Broadus et al (11), Birge et al (12), and Dokkum et al (13). Particularly, for comparative assessments of the absorption of calcium from coral-added crackers versus that from calcium carbonate-added crackers, measurements were carried out with the following five assay methods of Nicar and Pak and Harvey et al. Method I) Urinary calcium excretion (in mg) per milligram of creatinine during the first 4 h post-ingestion from 8:00 a.m. to noon. Method 2) Increment in urinary calcium excretion (in mg) per dL of OF during the latter half of the observation period, calculated by subtracting pre-ingestion urinary calcium excretion ( 6:00-8:00 a.m. ) from post-ingestion urinary calcium excretion ( 10:00 a.m. - noon ). Method 3) Increment in urinary calcium excretion (in mg) per dL of OF during the first half of the observation period, calculated by subtracting from post-ingestion urinary calcium excretion ( 8:00-10:00 a.m. ). Method 4) Urinary calcium excretion (in mg) calculated by subtraction of the urinary calcium excretion per milligram creatinine in non-cracker-ingested controls over 4 h, from 8:00 a.m. to noon , from post-ingestion urinary calcium excretion per milligram creatinine during 4 h, from 8:00 a.m. to noon . Urinary calcium excretion in mg/dL of OF was calculated by multiplying urinary calcium excretion (in mg) per milligram urinary creatinine by serum creatinine concentration (in mg/dL). (Blood collection was performed at 8;00 a.m. just prior to cracker ingestion and at noon (i.e., 2 h post-ingestion), and serum creatinine levels determined at these time points were used for the calculation.) Method 5) Determine the increase in serum calcium concentration (in mg/dL) by subtracting the serum calcium concentration in non-cracker-ingested controls from post-ingestion serum calcium concentration. Similar procedures were used for the evaluation of magnesium absorption. Inter-group comparisons were made using a paired. t-test. Urine samples were analyzed for calcium by the OCPC method ("Jisseiken" Ca, an auto analyzer system reagent; DIA-Iatron Co., Ltd., Tokyo, Japan), and for magnesium by the xylidyl blue method ("Jisseiken" Mg, an auto analyzer system. Coral-Derived Calcium Absorption by Humans Table 2. Calcium absorption from the intestine and serum calcium
collcci1trutioll following ingestion of calcium-supplemented crackers. RESULTS Calcium absorption Pertinent data are presented in Table 2. The group receiving coral-added crackers and that receiving calcium carbonate-added crackers were practically comparable with respect to urinary calcium excretion during 2-h pre-ingestion ( 6:00-8:00 a.m. ). Mean urinary calcium excretion after the ingestion of coral-added crackers was greater than that after calcium carbonate-added crackers by four determination methods, I) through 4). Significant intergroup differences were noted in urinary calcium excretion (fig/fig Cr) during 4-h post-ingestion ( 8:00 - noon ) Vol 45, No 5, 1999 Table 3. Increase in urinary calcium excretion (mg) per dL of glomerular filtrate during the latter half of the observation period ( 10:00 a.m. - noon ) after cracker ingestion in individual subjects. by Method I), increase in urinary calcium excretion (mg/dL OF) during the latter half of the post-ingestion observation period (10:00 a.m. to noon) by Method 2), and increase in urinary calcium excretion (A from control~ mg/mg Cr) during 4-h post-ingestion (8:00 a.m. to noon) by Method 4). However, Do significant difference was demonstrated for the first half of the post-ingestion observation period ( 8:00-10:00 a.m. ) by Method 3). These findings were generally in line with the conclusions from absorption studies on calcium citrate versus calcium carbonate by Harvey et al (8) and Nicar and Pak (9) that calcium citrate was better absorbed. The increase in serum calcium concentration calculated by subtraction of the control value from the post-ingestion serum calcium value (Method 5) also showed a significant difference between the two groups; hence, a similar tendency to that reported by Harvey et al. Individual assay data for the latter half of the post-ingestion observation period are presented in Table 3. The males exhibited a better calcium absorption from coral-derived calcium as compared with the females, though the subject sample sizes were small. Meanwhile, the increase in urinary calcium excretion during the subsequent 2-h period ( noon to 2:00 p.m. ), determined for reference, showed a plateau with no Coral-Derived Calcium Absorption by Humans Table 4. Increase in urinary magnesium excretion (mg) per dL of glomerular filtrate and serum magnesium concentration during the latter half of the observation period (IO:OOa.m.-noon) after cracker ingestion. appreciable difference between the two cracker regimens. It was thus considered appropriate to assess the responses by analyzing two consecutive 2-h post-ingestion urine samples for the comparison based on urinary calcium excretion. Magnesium absorption Intestinal magnesium absorption and increases in serum magnesium concentration following ingestion of the test crackers are shown in Table 4. The magnesium content of the coral-added cracker was as high as 252 mg while that of the calcium carbonate-added cracker. was only 42 mg. Significant intergroup differences were observed in respect of increment in urinary magnesium excretion during the latter half of the post-ingestion observation period (10:00 a.m. to noon) by Method 2) (p=0.001), and there was an increase in serum magnesium concentration at noon as compared to the serum magnesium value at 8:00 a.m. (p = 0.006). DISCUSSION The assessments of calcium absorption from supplemented crackers performed using five methods as described by Harvey et al (8) and Nicar and Pak (9) demonstrated a better absorption of coral-derived calcium than that of calcium carbonate-derived calcium on the average. A laboratory study in rats to explore the ability to utilize calcium derived from Ryukyuan coral which contains calcium and magnesium at a ratio of about 2-to-1 has been reported by Suzuki et al (14). The investigators calculated the calcium balance from excretions in the feces and urine during the last 3 d of a 4-wk rat feeding trial using coral. They concluded that the efficiency of calcium utilization was satisfactorily greater with coral-derived calcium as compared to calcium carbonate-derived calcium, although the difference observed did not attain a level of statistical significance. Suzuki et al also described that their concurrent test with a fivefold
increase in dietary magnesium intake (i.e., 0.25% as against 0.05%)
demonstrated a marked increase in urinary calcium excretion; hence,
a better calcium absorption in the group fed on high-magnesium (0.25%)
diet. While Suzuki et al have given no account of the high efficiency of calcium utilization from coral in their article, it would be reasonable toassume that the high magnesium content has some bearing upon the intestinal absorption of calcium when viewed together with consideration of the present human trial data. However , it is of importance to mention that problems such as coral calcium solubility in gastric acid, absorption from the intestine and reabsorption from the renal tubules per se should be discussed. Additionally, the potential involvement of magnesium and further basic studies are needed . The present data demonstrating the remarkably good absorption of calcium from coral containing calcium and magnesium in a ratio of 2-to-1 are of profound interest, and it is anticipated that Ryukyuan coral can be incorporated into a variety of inexpensive, light, tasty foods so as to enable a ready dietary intake of calcium and magnesium in a ratio of 2-to-l. The authors are gratefully indebted to Dr. Osamu Setoyama, Vice Director of the Clinical Division, Higashi Sapporo Hospital , and dietitians and other staff of the hospital for helpful discussion and expert cooperation throughout this study. REFERENCES Proposed Diagnostic Criteria for Osteoporosis (Jpn. Soc. Bone Metab., 1993). Recker RR. 1981. Continuous treatment of osteoporosis: Current status. Orthop Cli11 North Am 12: 611-627. Esashi T. 1992. Calcium and magnesium. Rinsho Eiyo (Clin Nutr) 81: 288-294. Karppanen H, Pennanen R, Passinen L. 1978. Minerals, coronary heart disease and sudden coronary death. Adv Cardiol 25: 9-24. Seelig MS. 1982. Magnesium requirements in human nutrition. 1 Med Soc 79: 849-850. ltokawa Y. 1990. Magnesium as a nutrient. Igaku no Ayumi (1 Clin Exp Med) 154: 213-216. The Declaration. of Helsinki (adopted in 1964; as amended in 1989). 1988. 1 Nutr Sci Vitaminol51: 41-42. Harvey JA, Zobitz MM, Pak CYC. 1988. Dose dependency of calcium absorption: A comparison of calcium carbonate and calcium citrate. 1 Bone Mineral Res 3: 253-258. Nicar MJ, Pak CYC. 1985. Calcium bioavailability from calcium carbonate and calcium
Broadus AE, Dominguez M, Bartter FC. 1978. Pathophysiol9gical studies in idiopathic hypercalciuria: Use of an oral calcium tolerance test to characterize distinctive hypercalciuric subgroups. J Clin Endocrinol Metab 47: 751-760. Birge SJ, Peck WA , Berman M, Whedon GD. 1969. Study of calcium absorption in man: A kinetic analysis and physiologic model. J Clin Invest 48: 1705-1713. van Dokkum W, de la Gueronniere V, Schaafsma G, Bouley C, Luten J, Latge C. 1996. Bioavailability of calcium of fresh cheeses, enteral food and mineral water: A study with stable calcium isotopes in young adult women. Br J Nutr 75: 893-903. Suzuki K, Uehara M, Masuyilma R, Gotou S. 1997. Calcium utilization from natural coral calcium~A coral preparation with a calcium-magnesium content ratio of 2 : I. Abstracts ofPapers Presented at the 44th Jpn. Soc. Nutr. Betterment, p. 145, Fukuoka . Vol 45, No 5, 1999 SHOWA WOMEN'S UNIVERSITY 1-7, Taishido, Setagaya-Ku, Tokyo 154 Japan Phone (03)3411-5111 Fax. (03)34137-6850 Tlx. 2425578 S~IOWAW July 24; 2000 THE PROBLEM ON THE LACK OF INGESTION OF CALCIUM AND MAGNESIUM IN JAPAN AND CORAL POWDER
After that, the data is still used through several revision. In the meanwhile, the ingested nutrition of the people is rising by the higher the national economy and the only nutrient substance which is still lower than the DA (Dietary Allowance) is Calcium (Ca) today. For this reason, in order to increase the ingestion of Ca, the development of Ca enriched food and the propaganda to increase the consumption of the food which are the supply source of Ca such as Milk and dairy products etc. are made and as the result the ingestion of Calcium is slightly upward tendency. But recently after the report that the death rate of Ischemic Heart Disease (IHD) is increased to correlated with the ratio between Ca and Magnesium (Mg) are published by Karppanen et al. (1978)[1]. The necessity of concerning not only to the ingestion of each minerals but also to make balance of correlated minerals are emphasized by Itokawa [2], Kimura[3] and Suzuki [4] et al; We have no data of ingestion of Mg in the National Nutrition Surveys of Japan which was done once a year from 1946 but following to the data by Itokawa et al., the ingestion of Mg which was surveyed from each stratum in Japan was about 150-250mg and this ingested Mg was only about 1/3- 1/2 compared with 500-600mg of ingestion of Ca. Concerning to the ratio of Ca/Mg, in Japan to keep 2:1 is preferable from the data of Karppanen et al. and RDA for the Japanese of Ca and Mg. Actually, it seems easy but is difficult to keep 2:1 for Ca/Mg by assortment of several food. Fortunately, it is realized to supply the Ca/Mg =2:1 by the utilization of coral which is accumulated in certain area of Okinawa in Japan. This Ca/Mg =2:1 is naturally well-balanced and contains other minute minerals. Ca/Mg , is this naturally well-balanced minerals comes from Okinawa. By the result of analysis, ordinary coral contains abt. 35% of Ca: and abt.2% of Mg but this special type of coral contains abt. 25% of Ca and abt.10% of. Mg which contents of Mg is higher 'than that of ordinary coral and the ratio of Ca/Mg is closely 2:1. We certified by the data of analysis of both authorized Research Laboratories in Japan and U.S.A.. And usually, ordinary coral sand accumulated on the bottom of the sea sometimes can not use for food-stuff as it contains silica sand but this special coral has not such trouble by the result of analysis. SHOWA WOMEN'S UNIVERSITY 1-7, Taishido, Setagaya-Ku, Tokyo 154 Japan Phone (03)3411-5111 Fax. (03)3487-6850 Tlx. 2425578 SHOWAW The Study on Nutrition of Coral Powder As the several testing results on Coral Powder given to the subjects are reported, I would like to explain about those results. 1. The Influence of Calcium Enriched Food and Exercise upon the Bone Density -I By Prof. Shizue Yamashita et al. (announced and published at Japan Nutrition and Food Society, 1997) . The influence of Ca enriched food and exercise upon the bone density objected 51 students from 19-32 years of age during 6 months are observed. ' The ingestion of Ca was 1,000mg which was consisted from 400mg by daily foods, 200mg by mill( and 400mg by coral powder. As for exercise, 90 minutes exercise for the purpose of weight control was charged for 1st Group, more than 40 minutes/Day and nearly 140 pulsation exercise was charged 3 times in a week for 2nd Group, 10,000 steps/Day of walking was charged for 3rd Group and exercise was charged for the purpose of weight control as 1st Group but digestion of Ca was not forced to charge for 4th Group. The change of the bone density of 3rd Group was the biggest from 95.4 at the beginning of the test to 96.3 at the end of the test. [6] 2. The Influence of Calcium Enriched Food and Exercise upon the Bone Density -II By Prof. Shizue Yamashita et al. (announced and published at Japan Nutrition and Food Society, 1998) The change of bone density by exercise in the case of charging of 600mgIDay of Ca and 300mgIDay of Mg derived from coral powder for one Group and charging of 200ml of mill{ for other Group were objected by 43 of female students from 19-27 years of age.
3. The Utilization of Calcium derived from Natural Coral Calcium By Prof. Kazuharu Suzuki et al. (announced and published at Japan Nutrition and Food Society, 1997) In order to compare the utility efficiency of Ca derived from natural coral powder which contains Ca/Mg at the rate of 2:1, 4 kinds of Ca, Coral Powder, Calcium Carbonate, Milk Calcium and Cow Bone Calcium, are given to 4 month old 30 Wister species rats during 4 weeks. In this case, to keep the amount of Mg controlled with Magnesium Oxide and controlled the ratio of Ca/mg as 2:1. 3 days before the end of feeding, the intake and out put are investigated by the ways of collecting dung and urine. After the feeding, the amount of Ca and Mg were measured from the extracted internal organs and blood serum separately. As the result, the reserved amount of Ca of Coral Powder Group was shown the highest value compared with other Groups. And the rate of the absorption of Ca of this group' in appearance was 69.6%. It was also the highest value compared with other groups. There was no difference between 4 groups about the thickness of Ca and Mg in blood serum, but HDL-the thickness of Cholesterol of Coral Powder was the highest value among 4 groups. As the result, the absorption of Ca of natural Coral Calcium was the better compared with Milk Ca, Cow Bone Ca and Calcium Carbonate. And Natural Coral Calcium seemed to give the favorable result for fat in the blood serum. [8] 4. Calcium Absorption from the ingestion of Coral Derived Calcium by Humans By Dr. Kunihiko Ishitani et al. (1999 Journal of Nutritional Science Vitamin L45.509~517) It is pointed out the defect that the mineral balance in the foods
last easily as the chance of ingestion of processed foods were so
often recently. As the conclusion of above introduced 4 reports, Ca and Mg contained Coral Powder was well absorbed in the human body and it was clear that it contributes for the improvement of bone density. / :y~,-.C/~ Hiroyasu ~Fukuba, Ph.D. Professor Showa Women's University
[ 1 ] J Karppanen et al. 1978 ...Mutual Relationship of Ischemic According to the bar graph shown on the left, only the adults living
in fishing villages of isolated islands are reaching Safe and Adequate
Daily Dietary Intakes of magnesium. Insufficiency in magnesium is
remarkable especially in children in their growth period. (source:
Dr Yoshinorl Itokawa, "The course of medical science [Igaku
no ayumi] (1990) pp154-213) |
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