Published: Calcified Tissue International (1996) 58:226‑230
Reference: Fujita T., Ohue T., Fujii Y., Miyauchi A., Takagi Y. “Heated oyster shell–seaweed calcium (AAACa) on [bone loss].” Calcif Tissue Int. 1996; 58(4):226‑230.
URL: https://pubmed.ncbi.nlm.nih.gov/8661952/ PubMed

Short summary:
In a 24‑month double‑blind study of elderly women (average age ~80), those receiving 900 mg/day of AAACa™ calcium showed significantly higher lumbar bone density and reduced parathyroid hormone levels compared to placebo. The calcium carbonate group showed no significant advantage.

Published: Journal of Bone and Mineral Metabolism (1997) 15:223–226
Reference: Fujita T., Fujii Y., Goto B., Miyauchi A., Takagi Y. “A three-year comparative trial: Effect of combined alfacalcidol and elcatonin on bone metabolism in elderly women.” J Bone Miner Metab. 1997; 15:223–226.
URL: https://link.springer.com/article/10.1007/BF02491385
📚 Springer Link →

Short summary:
In this 3-year study of elderly women with declining bone mass, the combination of AAACa™ with active vitamin D (alfacalcidol) and the hormone elcatonin was shown to further increase bone mineral density and reduce fracture risk, suggesting a potential additive benefit in certain populations.*

Published: Journal of Bone and Mineral Metabolism (1996) 14:31‑34 SpringerLink+2SpringerLink+2
Reference: Fujita T. “Calcium bioavailability from heated oyster shell–seaweed calcium (active absorbable algae calcium) as assessed by urinary calcium excretion.” J Bone Miner Metab. 1996;14:31‑34.
URL: https://link.springer.com/article/10.1007/BF01771671  SpringerLink

Short Summary:
In a crossover trial of healthy male volunteers, 1,000 mg of AAACa™ calcium resulted in a significantly greater increase in urinary calcium excretion (249% of baseline) compared with calcium carbonate (170% of baseline), indicating higher bioavailability of AAACa™.*

Published: Calcified Tissue International (1997) 60:506‑512 PubMed+1
Reference: Fujita T., Ohgitani S., Fujii Y. “Overnight suppression of parathyroid hormone and bone resorption markers by active absorbable algae calcium. A double‑blind crossover study.” Calcif Tissue Int. 1997; 60(6):506‑512.
URL: https://pubmed.ncbi.nlm.nih.gov/9164824/ PubMed+1

Short Summary:
In a 5‑day double‑blind crossover study of 9 healthy men, supplementation with AAACa™ calcium significantly lowered overnight parathyroid hormone levels and reduced bone resorption marker (Crosslaps) to ~40% of baseline, compared with placebo (~173%) and a lower dose calcium regimen (~97%). PubMed

Published: Journal of Bone and Mineral Metabolism (2000) 18:212‑215
Reference: Fujita T., Fujii Y., Goto B., Miyauchi A., Takagi Y. “Peripheral computed tomography (pQCT) detected short‑term effect of AAACa (heated oyster shell with heated algal ingredient HAI): a double‑blind comparison with CaCO₃ and placebo.” J Bone Miner Metab. 2000; 18(4):212‑215. PubMed+1
URL: https://pubmed.ncbi.nlm.nih.gov/10874600/

Short Summary:
In a 4‑month double‑blind study using pQCT in elderly women, those receiving AAACa™ with HAI™ had a significant increase in trabecular radial bone density (~106.2% of baseline), compared to calcium carbonate and placebo groups, indicating superior short‑term bone density effects.*

Published: Journal of Bone and Mineral Metabolism (2000) 18(3):165‑169
Reference: Fujita T., Fujii Y., Goto B., Miyauchi A., Takagi Y., Kobayashi S., Kamoshita K., Mikuni N., Kurihara Y., Shikauchi I. “Increase of intestinal calcium absorption and bone mineral density by heated algal ingredient (HAI) in rats.” J Bone Miner Metab. 2000;18(3):165‑169.
URL: https://pubmed.ncbi.nlm.nih.gov/10783851/

Short Summary:
In a rat study on a low‑calcium diet, the addition of HAI™ (an extract from heated sea algae) with AAACa™ calcium significantly increased intestinal calcium absorption and prevented bone mineral density loss, compared to control groups. *

Published: Journal of Bone and Mineral Metabolism (1998) 16:186‑189
Reference: Ohgitani S., Fujii Y., & Fujita T. “Calcium supplementation and parathyroid hormone.” J Bone Miner Metab. 1998;16(3):186‑189. SpringerLink+1
URL: https://link.springer.com/article/10.1007/s007740050044 SpringerLink+1

Short Summary:
In a 1‑week crossover study of 8 healthy young women, 600 mg/day AAACa™ calcium lowered fasting parathyroid‑hormone levels significantly and reduced markers of bone resorption more than milk calcium, suggesting higher bioavailability of AAACa™.*

Published: Mineral & Electrolyte Metabolism (1995) 21:229‑231
Reference: Fujita T., Ohue T., Fujii Y., Miyauchi A., Takagi Y.
https://pubmed.ncbi.nlm.nih.gov/7565455/

Summary:
AAACa™ supplementation (900 mg/day) helped preserve lumbar spine BMD in elderly women over 18 months. The study also found a significant drop in PTH levels, suggesting reduced bone resorption and improved calcium balance. *

Published: Journal of Bone and Mineral Metabolism (2000) 18:283‑286
Reference: Ohgitani S. & Fujita T. “Heated oyster shell with algal ingredient (AAACa) decreases urinary oxalate excretion.” J Bone Miner Metab. 2000; 18(5):283‑286.
URL: https://pubmed.ncbi.nlm.nih.gov/10959618/

Short Summary:
In a crossover study of nine healthy adults (ages 23–49), 800 mg/day of AAACa™ calcium reduced urinary oxalate excretion and the calcium × oxalate product more effectively than calcium carbonate or placebo—indicating superior potential for reducing stone‑forming burden.*

Published: Journal of Bone and Mineral Metabolism (1998) Vol 11, Supplement 3: S47‑S54
Reference: Fukuda S. “Effects of Active Amino Acid Calcium: Its Bioavailability on Intestinal Absorption, Bone Loss, and Removal of Plutonium in Animals.” J Bone Miner Metab. 1998; 11(S3):S47‑S54.
URL: https://link.springer.com/article/10.1007/BF02383541

Short Summary:
This animal study showed that AAACa™, a form of active amino acid calcium, enhanced intestinal calcium absorption, prevented bone loss, and promoted excretion of radioactive metals—highlighting its unique bioavailability and detoxifying properties. *

Published: Townsend Letter for Doctors & Patients, August/September 2002: pp. 110‑114
Reference: Brown S.E., “A Pilot Study Comparing AAACa and Calcium Citrate Supplementation in Menopausal U.S. Women.” Townsend Letter. 2002; Aug/Sep:110‑114.
URL: https://betterbones.com/wp-content/uploads/2016/11/advacal.pdf

Short Summary:
In a 4-week trial of 11 postmenopausal women with low calcium intake, AAACa™ supplementation (900 mg/day) lowered bone resorption markers (Dpd) by 43% versus 33% for calcium citrate. Notably, half of the AAACa group reduced their Dpd to near or below ideal premenopausal levels—while none in the citrate group achieved that range—suggesting superior bone-supportive effects from AAACa™. *

Published: Journal of Bone and Mineral Metabolism (2004) 22:32‑38 PubMed+1
Reference: Fujita T., Ohue M., Fujii Y., Miyauchi A., Takagi Y. “Reappraisal of Katsuragi Calcium Study, a prospective, double‑blind, placebo‑controlled study of the effect of active absorbable algal calcium (AAACa) on vertebral deformity and fracture.” J Bone Miner Metab. 2004;22(1):32‑38.
URL: https://pubmed.ncbi.nlm.nih.gov/14691684/ PubMed+1

Short Summary:
In elderly in‑patients receiving 900 mg/day AAACa™, there were fewer new vertebral fractures and less progression of spinal deformity compared to placebo or calcium carbonate—showing benefits beyond just BMD gains. *

Published: Journal of Bone and Mineral Metabolism (2007) 25:68‑73
Reference: Fujita T., Nakamura S., Ohue M., Fujii Y., Miyauchi A., Takagi Y., Tsugeno H. “Postural stabilizing effect of alfacalcidol and active absorbable algal calcium (AAACa) compared with calcium carbonate assessed by computerized posturography.” J Bone Miner Metab. 2007;25(1):68‑73. PubMed+1
URL: https://pubmed.ncbi.nlm.nih.gov/17187196/ PubMed

Short Summary:
In a 12‑month randomized study of 126 adults (ages 20–81), supplementation with 900 mg/day AAACa™ Ca (or alfacalcidol) significantly improved postural stability measures (track range and density) compared with calcium carbonate or no supplementation—suggesting benefits in reducing fall risk beyond bone density alone.*