Lactobacillus acidophilus La-14: A Strain Profile

Lactobacillus acidophilus La-14 is a probiotic strain supplied within IFF's HOWARU range and used in digestive and women's health products. It is well characterised in the laboratory for acid tolerance, adhesion and antimicrobial activity. Human trials of La-14 on its own are limited, and most clinical use combines it with other strains.

What is Lactobacillus acidophilus?

Lactobacillus acidophilus is a rod-shaped bacterium that ferments sugars into lactic acid and lives naturally in the human small intestine, mouth and vagina. Its name means "acid-loving", reflecting its tolerance of low pH.

When the genus Lactobacillus was split into 25 genera in 2020, L. acidophilus remained in the original genus because it is the type species around which the genus is defined. Many related organisms, such as L. rhamnosus and L. paracasei, received new genus names, but acidophilus did not.

The species was among the first lactic acid bacteria studied for health, with research dating to the early twentieth century. That long history includes many different strains, and their properties differ considerably.

How is La-14 different from other acidophilus strains?

Strains within L. acidophilus differ in genes for surface proteins, carbohydrate use and antimicrobial production. La-14 and NCFM, another HOWARU acidophilus strain, are often confused, but they are distinct strains with separate data.

NCFM has a larger body of human trials, including studies in children and in lactose maldigestion. La-14 has been studied mainly in the laboratory and in combination products. Findings for NCFM should not be assumed for La-14, or the reverse.

What has La-14 shown in the laboratory?

Laboratory characterisation of La-14 has examined the properties expected of a probiotic candidate:

Acid and bile tolerance. La-14 survives exposure to conditions simulating stomach acid and bile salts, suggesting a share of cells can reach the intestine alive.

Adhesion. It attaches to human intestinal cell lines in culture, which is considered a marker of potential interaction with the gut lining.

Antimicrobial activity. La-14 produces lactic acid and, in culture, inhibits the growth of several pathogens. Lactobacilli of this type can also produce bacteriocins, small antimicrobial proteins.

Immune signalling. In cell experiments, acidophilus strains interact with immune receptors and can shift the balance of signalling molecules called cytokines.

Laboratory results identify potential but do not show what happens in people. Bacteria behave differently in the crowded, variable environment of the human gut than in a culture dish.

What human research exists for La-14?

Published human studies including La-14 have mostly tested it alongside other strains, which makes the contribution of La-14 itself hard to isolate.

One line of research has combined La-14 with L. rhamnosus HN001 in oral supplements for women. In a small Italian study, both strains were recovered from vaginal samples after oral intake, indicating that orally taken lactobacilli can reach the vaginal environment. This is a colonisation finding rather than a demonstration of clinical benefit.

Studies of La-14 as a single strain for digestive symptoms in adults are scarce. Its use in gut wellness products relies on its characterisation, its tolerance and the general properties of acidophilus strains.

Why combine La-14 with HN001?

Combining La-14 with HN001 pairs two lactobacilli that occupy slightly different niches. L. acidophilus tends to colonise the small intestine, while L. rhamnosus strains persist well further along the gut.

MellowFlora from ELMED Life Sciences uses this pairing, providing HOWARU HN001 and HOWARU La-14 at 10 billion CFU per sachet as a daily product for adults with sensitive digestion. The evidence for HN001 and for the combination's intended use is set out in the guide to probiotic sachets for sensitive digestion and in Lactobacillus rhamnosus HN001: what the research shows.

What does acid tolerance mean in practice?

Laboratory tests expose bacteria to acid at pH 2 to 3 for one to three hours and count survivors. A strain that retains a large share of its cells passes this screen. The test is a useful filter because many bacteria die quickly in acid, but it cannot copy a real stomach, where food raises the pH for much of a meal and acid exposure varies by person and time of day.

For this reason, survival in a laboratory acid test is read as supporting evidence of suitability, not as proof that a defined number of La-14 cells reach the colon. Taking a probiotic with or shortly before a meal is a simple step that improves the odds.

Is La-14 safe?

L. acidophilus has a long history of safe consumption in fermented dairy foods and supplements, and La-14 has been well tolerated in published studies. People with severely weakened immunity, central lines, damaged heart valves or serious acute illness should seek medical advice before taking any probiotic. Follow the label and any advice from your doctor or pharmacist.