Benefits
Bone mineral density and bone turnover markers
In a 24-month randomized, double-blind trial in 300 postmenopausal women without osteoporosis, 2.4 g/day Aquamin (800 mg calcium), alone or with a prebiotic fiber, showed no significant difference in bone mineral density versus a maltodextrin control. The bone turnover markers CTX and osteocalcin fell more than with control. In lab cultures, it increased mineral deposits by bone-forming cells.
Joint comfort and walking distance in adults with knee discomfort
Two 12-week pilot trials funded by the maker tested 2,400 mg/day in adults with knee osteoarthritis. In one (70 randomized, 50 completed), pain improved within the Aquamin group, but the groups differed at baseline and walking distance did not differ from placebo. In the other (22 treated, 14 completed), WOMAC scores did not differ; range of motion and walking distance favored Aquamin at one visit only.
Colon bacteria and gut lining markers
In a 90-day university trial in 30 healthy adults, Aquamin (800 mg calcium/day) shifted the colonic bacterial community, lowered stool bile acids and slightly raised stool acetate, changes not seen with placebo. Minor side effects were reported by 3 of 10 people on Aquamin, 3 of 10 on placebo and 6 of 10 on calcium carbonate; the trial was too small to compare tolerability formally.
Blood cholesterol in postmenopausal women
In a secondary analysis of the 24-month trial in 300 postmenopausal women, LDL and total cholesterol were lower after Aquamin, alone or with a prebiotic fiber, than after maltodextrin. HDL cholesterol, triglycerides, blood pressure and body composition did not differ. Lipids were not the trial's main outcome.
Calcium with magnesium and trace elements
Aquamin supplies calcium with magnesium and measurable levels of 72 other trace elements from seawater. Whether the extra minerals add anything in people is uncertain. In a single-dose study in 12 women, parathyroid hormone stayed below placebo for longer after Aquamin than after calcium carbonate, a short-term marker only.
Mechanism of action
Calcium handling after a single dose
The published Aquamin trials have not measured calcium absorption directly. In a 12-woman single-dose crossover, 12-hour urinary calcium output rose more than with placebo after Aquamin F but not after calcium carbonate, and parathyroid hormone stayed lower for longer. These are indirect markers of calcium uptake.
Bone-forming cells in culture
In a cell study led by a researcher from the maker, Aquamin increased mineral deposits by pre-osteoblasts (cells that mature into bone-forming cells). Cell work points to a possible mechanism only; the 24-month human trial did not find a difference in bone density.
Gut bacteria and barrier proteins
In human colon tissue grown in the lab (organoids), Aquamin raised proteins that build the gut lining barrier and lowered some inflammation-related proteins. In a 90-day human trial it shifted colonic bacteria and lowered stool bile acids. Whether these changes affect digestion or bone has not been tested.
Clinical trials
Randomized, double-blind, four-arm pilot trial (NCT00452101) funded by Aquamin maker Marigot Ltd., which approved the protocol and reviewed the manuscript; a Marigot employee co-wrote it. Arms: glucosamine sulfate 1,500 mg/day, Aquamin 2,400 mg/day, both combined, or placebo, for 12 weeks. (Frestedt et al. 2008, Nutr J)
70 adults with moderate to severe knee osteoarthritis randomized; 50 completed.
Change in WOMAC pain differed between groups (p = 0.009), but the groups already differed at baseline in pain and stiffness, so the authors advise caution. Within the Aquamin group, WOMAC pain, stiffness and activity scores and walking distance improved (101 feet, about 7%), but the change in walking distance did not differ between groups. The combination arm, like placebo, showed no improvement. Adverse events did not differ.
Double-blind, placebo-controlled pilot trial (NCT00755482) funded by Marigot Ltd., which approved the protocol and reviewed the manuscript. By protocol, all participants halved NSAID use at week 2 and stopped it at week 4, with acetaminophen allowed for pain; Aquamin 2,400 mg/day or placebo for up to 12 weeks. (Frestedt et al. 2009, Nutr J)
29 adults with moderate to severe knee osteoarthritis randomized; 22 started treatment (8 Aquamin, 14 placebo) and 14 completed.
In the intention-to-treat analysis (n = 22), WOMAC scores did not differ from placebo, and walking distance did not differ across all visits. At the one-month visit, after two weeks at half the NSAID dose, extension range of motion (difference 5.2 degrees, p = 0.028) and 6-minute walking distance (difference 136 feet, p = 0.03) favored Aquamin; these gains did not continue once NSAIDs were stopped. The NSAID reduction was the protocol for both groups, not a result. Adverse events were similar.
Randomized, double-blind, controlled trial (ISRCTN63118444) at the University of Ulster. A secondary report of the same trial identifies the supplement as 2.4 g/day Aquamin providing 800 mg calcium. Arms: Aquamin, Aquamin plus short-chain fructo-oligosaccharides (a prebiotic fiber), or maltodextrin. (Slevin et al. 2014, J Nutr)
300 postmenopausal women without osteoporosis, followed for 24 months.
Change in bone mineral density did not differ from the maltodextrin control in either supplement group (intention to treat). The bone turnover markers osteocalcin and CTX fell more than with control at 12 or 24 months. In an exploratory subgroup with osteopenia, the fiber combination slowed total-body and spinal bone loss, only among women with higher baseline bone density, a finding the authors say needs further study.
Secondary analysis of the same randomized, double-blind trial; 2.4 g/day Aquamin supplied 800 mg calcium. Lipids were not the primary outcome. (Cronin et al. 2016, Br J Nutr)
300 postmenopausal women randomized to Aquamin, Aquamin with 3 g short-chain fructo-oligosaccharides, or maltodextrin.
After 24 months, LDL and total cholesterol were lower in both Aquamin groups than with maltodextrin. HDL cholesterol, triglycerides, body composition, blood pressure and cytokines did not differ, except IL-4, which rose with the fiber combination. At 4-year follow-up, reported diagnosed heart conditions did not differ between groups.
Double-blind crossover pilot; each woman received a single dose of Aquamin F, calcium carbonate or placebo, with blood and urine sampled over 12 hours. All three authors also ran the maker-funded knee trials; funding is not stated in the abstract. (Zenk et al. 2018, J Med Food)
12 fasting premenopausal women.
Urinary calcium output over 12 hours was higher with Aquamin F than placebo (P = .004); calcium carbonate did not differ from placebo. After a meal, parathyroid hormone was lower than placebo at 90, 120 and 240 minutes with Aquamin F and only at 90 minutes with calcium carbonate. These are short-term markers, not bone outcomes.
Randomized, double-blind, three-arm pilot trial at the University of Michigan funded by the NIH (including the Office of Dietary Supplements); Marigot Ltd. donated the Aquamin. Aquamin delivered 800 mg calcium/day; comparators were 800 mg/day calcium carbonate and maltodextrin. (Aslam et al. 2020, Cancer Prev Res (Phila))
30 healthy adults (10 per arm), with colon biopsies and stool samples before and after 90 days.
Aquamin lowered total colonic bacterial DNA, shifted the microbial community, lowered stool bile acids and slightly raised stool acetate. The comparator arm showed a smaller drop in bacteria and no bile acid or acetate change; placebo showed none. All 30 completed without serious adverse events or changes in liver or kidney markers. The authors call the findings preliminary.