Research shows that two special salts added to milk, sodium citrate and sodium hexametaphosphate, significantly change how milk proteins are digested in the stomach. According to Gram Research analysis, sodium citrate prevents milk from forming hard clots that are difficult to digest, while sodium hexametaphosphate slows down the enzyme that breaks down milk proteins, leaving 40 to 44 percent of the protein undigested after 60 minutes compared to complete digestion in untreated milk. These findings suggest these additives could make milk easier to digest for babies and elderly people.
Researchers studied how two types of special salts added to milk affect the way our stomachs break down milk proteins. According to Gram Research analysis, these salts, called sodium citrate and sodium hexametaphosphate, change how milk proteins clump together when they enter the stomach. The study found that these salts can prevent the hard clots that form when milk is digested, which is especially helpful for babies and elderly people who struggle to break down these clots. The findings suggest these salts could make milk easier to digest for people with sensitive stomachs.
Key Statistics
A laboratory study published in the Journal of Dairy Science in 2026 found that milk treated with 10 or 100 millimolar sodium citrate failed to form any clot during early digestion, compared to untreated milk which formed a clot with a strength of 305 pascals after 30 minutes.
Research shows that milk containing 100 millimolar sodium hexametaphosphate retained 43.5 percent of its intact casein protein after 60 minutes of digestion, while untreated milk was completely broken down by the digestive enzyme pepsin.
A 2026 laboratory analysis found that sodium citrate and sodium hexametaphosphate work through different mechanisms: sodium citrate prevents protein clumping while sodium hexametaphosphate reduces the activity of pepsin, the main protein-digesting enzyme in the stomach.
The Quick Take
- What they studied: Whether two types of special salts added to milk change how stomach acid and digestive enzymes break down milk proteins
- Who participated: This was a laboratory study using milk samples treated with different amounts of two salts: sodium citrate and sodium hexametaphosphate. No human participants were involved.
- Key finding: Milk treated with sodium citrate did not form hard clots in the stomach, while milk with sodium hexametaphosphate slowed down protein digestion. After 60 minutes of digestion, untreated milk was completely broken down, but milk with the highest dose of sodium hexametaphosphate still had 40 to 44 percent of its protein intact.
- What it means for you: These salts could help make milk easier to digest for babies and older adults who have trouble breaking down milk protein clots. However, more research is needed to confirm these benefits work the same way in real human digestion.
The Research Details
Scientists conducted a laboratory experiment to watch what happens when special salts are added to milk and then exposed to stomach acid and pepsin, the main enzyme that breaks down proteins in the stomach. They tested two different salts at various concentrations, ranging from 1 to 100 millimolar (a measure of concentration). The experiment had two stages: the first stage mimicked early digestion when the stomach is less acidic, and the second stage mimicked later digestion when the stomach becomes very acidic. During each stage, researchers measured how quickly milk proteins clumped together, how strong those clumps were, and how fast the digestive enzyme broke down the proteins.
To measure clumping, scientists used a technique called rheology, which measures how thick or gel-like a substance becomes. They also extracted protein clots at different time points and weighed them to see how much clumping occurred. Finally, they used gel electrophoresis, a laboratory technique that separates proteins by size, to track exactly which milk proteins were being broken down and when.
This approach allowed researchers to see the complete picture of how these salts affect milk digestion from start to finish, mimicking what happens in the human stomach.
Understanding how these salts affect milk digestion is important because many dairy products, including infant formula and protein drinks, already contain these salts. If these salts make milk easier to digest, they could be especially beneficial for babies and elderly people whose digestive systems struggle with milk proteins. This research provides the scientific foundation for potentially improving these products.
This was a controlled laboratory study, which means researchers could carefully control all the conditions and measure specific outcomes precisely. However, because it was done in test tubes rather than in human bodies, the results may not perfectly match real digestion. The study was published in the Journal of Dairy Science, a respected scientific journal. The researchers used multiple measurement techniques to verify their findings, which strengthens the reliability of the results.
What the Results Show
In the early digestion stage (high pH), untreated milk formed a strong clot with a strength of about 305 pascals (a unit of pressure) after 30 minutes. This clot is what makes milk hard to digest for some people. However, when researchers added the higher doses of sodium citrate (10 or 100 millimolar), the milk did not form any clot at all. The storage modulus, a measure of clot strength, stayed below 0.70 pascals, meaning the milk stayed liquid instead of turning into a gel.
In the later digestion stage (low pH), all milk samples were broken down by pepsin, but at different speeds. Untreated milk was completely digested after 60 minutes. Milk with sodium citrate was broken down slightly more slowly, but the difference was small. However, milk with sodium hexametaphosphate showed dramatically slower digestion. After 60 minutes, 40 to 44 percent of the milk protein remained unbroken in samples with the highest dose of sodium hexametaphosphate, compared to complete digestion in the control samples.
These results show that the two salts work very differently. Sodium citrate prevents clotting altogether, while sodium hexametaphosphate slows down the enzyme that breaks down proteins. The effect of both salts depends on how much is added to the milk.
The study revealed that the concentration of salt matters significantly. At lower concentrations (1 millimolar), the effects were much weaker than at higher concentrations (10 to 100 millimolar). This suggests there is a threshold amount needed before these salts have a noticeable effect on digestion. Additionally, the two salts appear to work through different mechanisms: sodium citrate works by keeping proteins from clumping together, while sodium hexametaphosphate appears to interfere with the pepsin enzyme itself, making it less effective at breaking down proteins.
Previous research has shown that milk proteins naturally clump together when exposed to stomach acid, forming a solid mass that is harder to digest. This study builds on that knowledge by showing that specific food additives can prevent or slow down this process. The finding that sodium hexametaphosphate can reduce pepsin activity is particularly interesting because it suggests these salts do more than just change protein structure; they may actually affect how digestive enzymes work.
This study was conducted in laboratory conditions using milk samples, not in living human bodies. Real digestion involves many other factors, including movement of food through the stomach, mixing with other digestive juices, and the unique characteristics of each person’s digestive system. The study did not measure whether the changes in digestion actually led to better nutrient absorption or easier digestion in real people. Additionally, the study did not test whether these effects would be the same in infant formula or other dairy products that contain additional ingredients. The researchers themselves noted that more advanced digestion models that better mimic human digestion are needed to confirm these findings.
The Bottom Line
Based on this research, sodium citrate and sodium hexametaphosphate show promise for making milk easier to digest by preventing clotting or slowing protein breakdown. However, these findings are preliminary and come from laboratory studies. Before making changes to infant formula or other dairy products based on this research, manufacturers should conduct human studies to confirm the benefits and ensure safety. For consumers, this research suggests that dairy products containing these salts may be easier to digest, but individual results may vary.
This research is most relevant to babies and elderly people who have difficulty digesting milk proteins and experience digestive discomfort. It is also important for manufacturers of infant formula, protein-fortified beverages, and other dairy products. People with lactose intolerance or milk allergies should note that this research focuses on protein digestion, not lactose or allergic reactions. Anyone with serious digestive problems should consult a healthcare provider rather than relying solely on product changes.
If these salts are incorporated into dairy products, any benefits would likely be noticed within a single meal or shortly after consuming the product, since digestion happens relatively quickly. However, long-term benefits for overall digestive health would require consistent use over weeks or months.
Frequently Asked Questions
Do emulsifying salts in milk make it easier to digest?
Laboratory research suggests that sodium citrate and sodium hexametaphosphate may make milk easier to digest by preventing clot formation or slowing protein breakdown. However, these findings are from test-tube studies, not human trials, so real-world benefits remain unclear.
What are emulsifying salts and why are they added to dairy products?
Emulsifying salts like sodium citrate and sodium hexametaphosphate are food additives that keep proteins stable and prevent separation in dairy products. They are commonly used in infant formula and protein-fortified beverages to improve texture and shelf life.
Is sodium hexametaphosphate safe for babies?
Sodium hexametaphosphate is approved for use in infant formula by food safety agencies, but this study only examined how it affects protein digestion in laboratory conditions. Parents should consult pediatricians about specific formula choices.
Can these salts help with lactose intolerance?
This research focuses on milk protein digestion, not lactose digestion. These salts would not help with lactose intolerance, which is caused by difficulty digesting lactose sugar, not milk proteins.
How much of these salts are in commercial dairy products?
The study tested concentrations from 1 to 100 millimolar, but the exact amounts in commercial products vary by manufacturer. Check product labels for sodium citrate or sodium hexametaphosphate to see if your dairy products contain these additives.
Want to Apply This Research?
- Track digestive comfort after consuming dairy products with these additives by rating bloating, cramping, and overall comfort on a scale of 1 to 10 within 2 hours of consumption. Compare ratings between products with and without these salts over a 2-week period.
- Switch to dairy products containing sodium citrate or sodium hexametaphosphate if you experience digestive discomfort with regular milk products. Start with one product and track your symptoms for one week before trying another brand.
- Create a weekly digestive comfort log noting which dairy products you consumed, their salt additives, and your digestive symptoms. After 4 weeks, review patterns to identify which products work best for your digestion.
This research was conducted in laboratory conditions using milk samples, not in human bodies. The findings are preliminary and should not be used to make medical decisions without consulting a healthcare provider. Parents considering changes to infant formula should speak with their pediatrician first. This information is not intended to diagnose, treat, cure, or prevent any disease. If you have digestive problems or concerns about milk digestion, consult a qualified healthcare professional.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.