does salt kill probiotics bacteria

Does Salt Kill Probiotics? (how it affects good bacteria)

For this article, I scout through various scientific findings to find out if salt kills probiotics or not and what is the best way to pursue this combination.

Key Highlights
  • Salt inhibits the growth of both good and bad bacteria, but different probiotic species have varying resistance to high salt concentrations.
  • Most salt-sensitive probiotics may get killed at salt concentrations greater than 2%, while others don’t lose activity until the salt ratio is well above 10%.
  • High salt intake reduces the gut’s natural microbial diversity and alters its composition, which may cause diseases.
  • Over-consuming salt in any form, even fermented foods, may cause you to lose good gut inhabitants.

To make it easier for you to understand how it all works, I have discussed, in detail, the effect of salt on probiotics, either in food or the gut, and what efforts you can consciously make to support their survival in both cases.

So, keep reading to find out all about it.

How Does Salt Affect Probiotics?

Salt on wooden surface

Different probiotic species have varying resistant potentials against high salt concentrations. Nonetheless, multiple research papers suggest that a high salt intake reduces the gut’s natural microbial diversity and alters its composition, which may cause diseases.

In the following sections, I will walk you through the scientific evidence that shows how salt affects probiotics.

You Might Lose The Probiotic Protection If Your Gut Environment Is Too Salty

Studies demonstrate that an increased sodium intake alters the gut microbial composition, which may drive the development of salt-induced hypertension or autoimmune diseases.

In one study, the scientists observed that the rats that were fed 8% salt lost 12 bacteria in the Bacteroidetes phylum, eight bacteria belonging to Firmicutes, and two from Proteobacteria.

Simultaneously, there was an increase in the Firmicutes to Bacteroidetes ratio, which indicates dysbiosis in the gut microbiome.

All these changes were accompanied by higher systolic and diastolic blood pressure.

Parallel to this, studies suggest that Bacteroides thetaiotaomicron, a member of the Bacteroidetes phylum, has anti-inflammatory properties and lowers blood pressure.

Similarly, another murine study found that giving rats Lactobacilli probiotics and a high salt diet kept the blood pressure under control and ameliorated their multiple sclerosis (an autoimmune disease) symptoms.

Some of your gut friends might survive your salt intake better than others

An in-vitro study checked the viability of three probiotic bacteria (Lactobacillus acidophilus, Lactobacillus casei, and Bifidobacterium longum species) at different salt concentrations (0-5%).

According to the results, L. casei was least affected by high salt concentrations.

Compared to this, B. longum met the steepest decline in its activity, even at lower concentrations.

Furthermore, L.acidophilus was fairly resistant at less than 2.5% NaCl, but at higher concentrations, it began to lose its metabolic activity but retained viability. 

The trend of salt resistance ranging from more to less in the three probiotic species can be represented as follows:

L. casei > L. acidophilus> B. longum.

Too Much NaCl May Wipe Out Even The Most Resistant Gut Commensals

In a pilot study, 12 healthy males were given 6000 mg (which is 2.6 times the recommended range) of salt for 14 days, and its impact on the Lactobacillus species in the gut was observed.

Ultimately, the fecal analysis revealed that the participants had lost nine out of ten Lactobacillus species by the end of the study.

Similarly, a study checked the ability of L. acidophilus, L. casei, and Bifidobacterium bifidum to attach to the intestinal cells and remain viable at different salt concentrations (10.0, 7.5, 5.0, 2.5).

The results showed that B. bifidium and L. acidophilus start losing their adhesion ability at all concentrations, but L. casei only gets affected when the concentrations exceed 5%.

Does Salt Kill Bacteria In Food?

Yes, salt does kill bacteria in food which also explains why it is extensively used in different preservation strategies. It does this by sucking out the water from the bacterial cells and dehydrating them.

probiotic foods for gut health

Nonetheless, some bacteria are adapted to salty environments. This is why in fermented foods like kimchi, sauerkraut, and miso, salt is used to kill the bad bacteria, whereas the probiotic strains can proliferate normally. 

Additionally, as I mentioned above, the probiotic species L. casei can be utilized in food preparations that contain a salt concentration of up to 5%.

Even so, the over-consumption of fermented foods may cause you to exceed your daily salt value, which may kill the probiotic bacteria in the gut.

So, here is how you can go about salt, food, and probiotics:

Salty Probiotic Food Is Okay, But Too Much Salt In Food Is Not

You can satisfy your taste palate while simultaneously getting in beneficial probiotics with certain foods.

For instance, the final salt concentration of kimchi ranges between 2-5%, and it also has probiotic lactic acid bacteria (LAB) such as Leuconostoc, Weissella, and Lactobacillus.

But still, over-consuming salt in any form, even fermented foods, may cause you to lose the good gut inhabitants.

So, for reference, the Dietary Guidelines for Americans (DGA) recommends that adults and children who are 14 years or older should limit their daily salt intake to less than 2300 mg.

For 2–13-year-olds, this upper limit should be reduced further.

How much black salt per day? (to keep good gut bacteria from dying)

According to WebMD, black salt should not be taken more than 6 grams per day, and in case you have high blood pressure take less than  3.75 grams per day. 

This range may coincide with the range at which most gut bacteria can survive. The reason is that staying within this range may prevent diseases, and the gut microbiota is associated with good health, stable blood pressure, and strong immunity.

Effect Of Salt On Yogurt: Does salt kill probiotics in yogurt?

The effect of salt in yogurt is dependent on its concentration, but if it is kept less than 2%, it may help to kill the bad bacteria and not alter a lot of probiotic properties as well.

According to the U.S guidelines, yogurt should basically contain two probiotic strains, namely Streptococcus thermophilus and L. bulgaricus.

However, manufacturers may also add L. acidophilus, Bifidobacterium lactis, L. rhamnosus, or L. paracasei species to it. 

For instance, a study found that Streptococcus thermophilus didn’t survive in cultures that have a sodium concentration higher than 2%.

Similarly, another study reported that the L. paracasei present in probiotic foods like yogurt remains viable at pH 5 and a salt concentration of 2-3%.

Considering this, the salt concentration of yogurt should be kept at less than 2% so that both main and optional strains can survive.


Does Salt Kill Probiotics In Sauerkraut?

Yes, higher salt concentrations may inhibit the lactic acid bacteria (LAB) probiotics during the starting phases of sauerkraut fermentation. However, in the later stages, the yeast and LAB start consuming sugar to produce carbon dioxide and achieve a state of equilibrium. 

The research studied the changes during sauerkraut fermentation at different salt concentrations and concluded that 5% salt is ideal for producing high-quality sauerkraut.

Does Salt Kill Lactobacillus In Curd?

Yes, although Lactobacillus species are sensitive to different amounts of salt in curd. But still, most of them, even the most resistant L. casei, may get inhibited at concentrations higher than 5%.

Does Salt Water Kill Good Bacteria? 

Yes, salt water may swish away some, if not all, the good bacteria. This is because most Bifidobacterium species and some Lactobacillus species are very sensitive to high salts.

Does Salt Kill Bacteria In Food

Yes, salt may kill both good and bad bacteria in the food according to their resistance potential.

My Wrap-up on Probiotics & Salts

Salt does kill susceptible probiotic bacteria by disrupting their cell membranes. Nonetheless, many of these species, like L. casei, remain viable unless the concentration starts increasing from 5%.

Moreover, fermented foods like kimchi are a perfect example of which probiotic species and what salt concentration can effectively be paired together (Lactobacillus species, 2-5% salt)

But still, don’t exceed the recommended salt intake, even if it is in the form of probiotic foods, because it may instead damage your gut microbiome.

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