Echinacea killed respiratory viruses, and probiotics and vitamin D reduced respiratory infections, three new studies reveal.
In a lab study, researchers introduced several cold and flu viruses into human bronchial cells and found that the herb echinacea significantly reduced the ability of the viruses to enter the cells. In addition, echinacea killed off many of the viruses, leading doctors to conclude that echinacea preparations can alleviate cold and flu symptoms.
In a review of 14 respiratory infection studies that used the probiotics Lactobacillus or Bifidobacterium, researchers found that, overall, probiotics reduced the severity and duration of symptoms compared to placebo.
In a respiratory infection study, researchers measured blood levels of vitamin D in about 19,000 adults and adolescents, 19 percent of whom had had a recent cold. Among those with the lowest vitamin D levels, 24 percent had infections compared to 17 percent of those with the highest vitamin D levels.