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Disodium Phosphate Dihydrate

Also known as: Disodium hydrogen phosphate dihydrate, Sodium phosphate dibasic dihydrate, Na2HPO4·2H2O, Disodium phosphate dihydrate

Overview

Disodium phosphate dihydrate is an inorganic sodium phosphate salt primarily utilized as a buffering agent, emulsifier, and sequestrant in various food and pharmaceutical applications. While it occurs naturally in phosphate rock, it is typically synthesized industrially for commercial use. In the context of dietary supplements, it may be included as a source of phosphate ions or as a pH stabilizer. Although its safety in food and cosmetic applications is well-established, direct clinical evidence specifically supporting its efficacy as a supplement ingredient for health benefits is limited. Research on phosphate salts generally focuses on their metabolic and toxicological effects rather than specific therapeutic uses in supplementation.

Benefits

There is no strong evidence from high-quality randomized controlled trials (RCTs) or meta-analyses to support direct health benefits of disodium phosphate dihydrate supplementation. While phosphate is an essential mineral crucial for bone health, ATP production, and cellular metabolism, excess intake can lead to adverse effects, particularly on kidney and cardiovascular health. Clinical research on phosphate-lowering therapies (which is distinct from phosphate supplementation) has shown effects on serum phosphate and urinary excretion, but the overall clinical outcomes remain unclear, highlighting the complex nature of phosphate metabolism in humans. Therefore, specific health benefits from supplementing with disodium phosphate dihydrate are not currently substantiated by robust scientific evidence.

How it works

Disodium phosphate dihydrate dissociates in aqueous solutions, releasing phosphate ions (PO4^3-) and sodium ions. Phosphate ions are fundamental for numerous physiological processes, including the synthesis of adenosine triphosphate (ATP) for energy, the mineralization of bones and teeth, and various cellular signaling pathways. Once absorbed, phosphate ions influence serum phosphate levels, modulate the secretion of parathyroid hormone (PTH), and play a role in bone remodeling processes. However, excessive phosphate intake can lead to elevated serum phosphate and PTH levels, which in animal models have been associated with reduced bone mineral density and kidney damage.

Side effects

Disodium phosphate dihydrate is generally recognized as safe (GRAS) for use in food and cosmetic applications at typical concentrations. Animal studies indicate low acute toxicity with high oral LD50 values (>1000 mg/kg). However, chronic high-dose exposure in animal models has been shown to cause adverse effects, including increased serum parathyroid hormone (PTH), decreased bone mineral density, and kidney damage (nephrocalcinosis). Due to limited clinical data on its use as a direct supplement, common side effects in humans are not well-documented. Potential risks associated with excessive intake or in susceptible populations include disturbances in mineral metabolism and adverse cardiovascular effects. While no specific drug interactions are widely reported for disodium phosphate dihydrate, it should be used cautiously or avoided in individuals with kidney disease or pre-existing disorders of phosphate metabolism, as it can exacerbate phosphate accumulation and related complications.

Dosage

There is no established minimum effective dose or optimal dosage for disodium phosphate dihydrate supplementation due to a lack of clinical efficacy data. The typical dietary phosphate intake from food sources ranges from 700 to 1400 mg/day. Supplemental phosphate salts should not exceed this range without medical supervision, given the potential for adverse effects. Safety assessments in animals suggest that doses above several hundred mg/kg/day may lead to adverse effects; human equivalent doses would be considerably lower. Specific recommendations regarding timing of intake or optimal forms for absorption are not established, as the primary focus of research has been on its safety as a food additive rather than its role as a direct supplement.

FAQs

Is disodium phosphate dihydrate safe as a supplement?

It is generally safe at low levels found in food, but high doses or chronic intake may pose risks to bone and kidney health, especially in susceptible individuals. Clinical data on its safety as a direct supplement are limited.

Does disodium phosphate dihydrate improve bone health?

There is no direct evidence that supplementing with disodium phosphate dihydrate improves bone health. In fact, animal studies suggest that excess phosphate intake may negatively impact bone mineral density.

Can disodium phosphate dihydrate affect cardiovascular health?

Elevated serum phosphate levels are linked to an increased risk of cardiovascular disease. However, the direct effects of disodium phosphate dihydrate supplementation on cardiovascular health in humans are not clearly established.

Should people with kidney disease avoid disodium phosphate dihydrate?

Yes, individuals with kidney disease should generally avoid disodium phosphate dihydrate supplementation due to the risk of phosphate accumulation, which can lead to serious complications and worsen kidney function.

Research Sources

https://www.cir-safety.org/sites/default/files/phoslt032016tent.pdf – This systematic review assessed the safety of phosphoric acid and its salts, including disodium phosphate dihydrate. It found high oral LD50 values in animal studies, indicating low acute toxicity. However, chronic high-dose exposure in animals led to kidney damage and bone changes, highlighting potential risks with prolonged or excessive intake.
https://www.ncbi.nlm.nih.gov/books/NBK601526/ – This toxicological review, which included controlled animal studies, investigated inorganic phosphates. It reported that high doses of phosphate in rats resulted in increased serum parathyroid hormone (PTH), decreased bone mineral density, and heightened osteoclast activity, suggesting adverse effects on bone metabolism.
https://pubmed.ncbi.nlm.nih.gov/34645696/ – This meta-analysis of randomized controlled trials focused on phosphate-lowering therapies in humans with hyperphosphatemia. While it confirmed that these therapies effectively reduce serum phosphate, the clinical benefits were unclear, and the relevance to phosphate supplementation in healthy individuals is indirect.