What Is Disodium Phosphate and Why Is It in Food?
Disodium phosphate, also known as sodium phosphate dibasic, is a chemical compound commonly used as a food additive with the European food additive number E339(ii). It serves several purposes in processed foods, including maintaining quality and texture. It is derived from phosphate rock, resulting in an inorganic phosphate that is more easily absorbed by the body than natural phosphorus.
Disodium phosphate's key uses in the food industry include functioning as an emulsifier to bind water and fat in products like cheese, a stabilizer in dairy to prevent separation, and a preservative to extend shelf life. It also acts as a flavor enhancer due to its sodium content, a pH regulator to maintain product quality, and a moisture retention agent in processed meats. Consequently, disodium phosphate is present in various processed and packaged foods, such as cheeses, cured meats, sodas, and cereals.
The Regulatory Perspective on Disodium Phosphate
Regulatory bodies like the FDA in the United States and the EFSA and JECFA in Europe evaluate and approve food additives such as disodium phosphate. The FDA has deemed DSP as "Generally Recognized As Safe" (GRAS), while European authorities have also approved its use, setting an acceptable daily intake (ADI) for total phosphate. These approvals are based on toxicological studies indicating low acute oral toxicity and no genotoxicity or carcinogenicity concerns. However, these regulations are based on consumption within established limits and may not fully address potential excessive intake from diets high in processed foods containing various phosphate additives.
Health Implications of Phosphate Intake
While moderate amounts of DSP are safe for most healthy individuals, the higher absorption rate of inorganic phosphates in food additives compared to natural phosphorus raises health concerns for some people.
Risks for Individuals with Kidney Disease
For those with chronic kidney disease (CKD), impaired kidney function hinders the body's ability to filter out excess phosphate, potentially leading to hyperphosphatemia. This condition of high blood phosphate levels can worsen kidney function and increase cardiovascular disease risk. The National Kidney Foundation advises against taking sodium phosphate as a medication for individuals with kidney disease.
Cardiovascular Health Concerns
Elevated phosphate levels in the blood have been linked to an increased risk of cardiovascular problems like heart attacks and strokes, even in people without kidney issues. This suggests that consuming excessive phosphate additives over time might be a risk factor for heart disease. However, further research is needed to confirm a direct causal link.
The Danger of High-Dose Laxative Use
Using high doses of over-the-counter (OTC) sodium phosphate products as laxatives can be risky. The FDA issued a warning in 2014 about the dangers of exceeding recommended doses, which can cause severe dehydration, rare but serious electrolyte imbalances, and damage to the kidneys and heart. This risk is higher for older adults, young children, and those with pre-existing medical conditions.
Disodium Phosphate Comparison Table
| Feature | Disodium Phosphate (Food Additive) | Natural Phosphorus (Whole Foods) |
|---|---|---|
| Source | Produced synthetically from phosphate rock. | Occurs naturally in food sources like legumes, nuts, and dairy. |
| Absorption Rate | Highly bioavailable and absorbed almost completely by the body. | Less efficiently absorbed due to its binding with other molecules. |
| Dietary Context | Primarily found in processed, packaged, and fast foods. | Found in nutrient-dense, unprocessed foods. |
| Health Impact | Chronic excessive intake linked to kidney and heart risks for susceptible individuals. | Absorbed and utilized by the body for healthy bone and cellular function. |
How to Reduce Dietary Phosphate Intake
Reducing consumption of processed foods is the most effective way to lower dietary phosphate intake, particularly for those concerned about kidney or heart health.
Focus on a diet rich in whole, unprocessed foods like fresh fruits, vegetables, and lean meats without added solutions. Carefully read ingredient labels on packaged foods to identify additives containing "phosphate". Cooking meals at home gives you control over ingredients and helps avoid hidden phosphate additives. Choose fresh meat and poultry that haven't been injected with phosphate solutions. Limiting or avoiding sodas, especially dark-colored ones containing phosphoric acid, is also recommended.
Conclusion
Regulatory bodies like the FDA and EFSA consider disodium phosphate safe in the limited amounts typically found in a balanced diet for most healthy people. The primary concern regarding how safe is disodium phosphate stems from the overall impact of a diet heavy in processed foods, which contain high levels of easily absorbed inorganic phosphates. This excessive intake poses a significant health risk, particularly for vulnerable groups like those with kidney disease. The best strategy for minimizing exposure to phosphate additives and supporting long-term health is to reduce processed food consumption, scrutinize ingredient labels, and adopt a whole-foods-based diet.
