Lactococcus acidophilus is commonly confused with Lactobacillus acidophilus, but strictly speaking, Lactococcus acidophilus is not an established or recognized species in scientific literature. However, Lactobacillus acidophilus is widely studied and sometimes used in probiotic formulations to support lactose intolerance. The rationale for using Lactobacillus acidophilus is that it produces the enzyme β-galactosidase (lactase), which helps break down lactose in the digestive tract, potentially alleviating symptoms for lactose-intolerant individuals.

Several studies have shown that certain strains of Lactobacillus acidophilus can survive passage through the gastrointestinal tract and assist in lactose digestion, leading to reduced symptoms such as bloating, gas, and diarrhea when consuming dairy. However, the scientific evidence is somewhat mixed: meta-analyses and systematic reviews suggest that the benefit is modest and can vary depending on the strain, dosage, and individual patient factors. Some studies report statistically significant reductions in symptoms, while others find little effect compared to placebo.

Overall, while there is some scientific basis for the use of Lactobacillus acidophilus as a probiotic to support lactose digestion, the strength of the evidence is not robust and it is not universally effective. Thus, the evidence rating here is 2, indicating weak to moderate support based on current research.