I have recently heard of several cases of influenza locally. There are reports coming out that this year's flu vaccine still has some anti-flu activity but it is not as effective as was hoped. Therefore, both vaccinated and non-vaccinated people have been asking for tips about how they can stay well this winter season.
You probably know the basics already--proper handwashing, plenty of sleep, adequate hydration, regular exercise, and time to relax and manage the daily stress of life. They are so important and foundational that they are worth mentioning again, though...
The picture above is a black elderberry plant. Elderberry has been shown to inhibit the activity of human influenza A. It's inhibition activities compare favorably to the popular medication Tamiflu according to one study. (Roschek B, Jr, Fink RC, McMichael MD, et al. Elderberry flavonoids bind to and prevent H1N1 infection in vitro. Phytochemistry 2009;70:1255-61). Influenza and other viruses use hemagglutinin to bind to the epithelial cells of the respiratory tract. Elderberry helps to neutralize this hemagglutinin activity and prevent viral binding to your cells. (http://cms.herbalgram.org/herbclip/pdfs/070752-297.pdf). Furthermore, the flu virus uses an enzyme called neuraminidase to enter the cell once it is attached. Elderberry also has the ability to inhibit neuraminidase activity (http://www.biomedcentral.com/1472-6882/11/16#B4).
If you research elderberry on the internet, you may come across several warnings stating this is a toxic plant. Not quite so. Eating the red berries can be toxic, so you want to make sure you are using the black elderberry (Sambucus nigra). Eating raw berries (even black) can cause nausea, vomiting and diarrhea if over consumed. Thus, it is recommended that you consume properly dried berries or cooked preparations. It is often prepared as a syrup, which has been cooked. These berries have been consumed for centuries. It is said that Charlemagne decreed that an elder be planted in every yard for its medicinal value (it has several other health-promoting properties as well). Historically, this plant is considered to be a protector of children and infants and has been used to treat many croupy coughs of infants. Therefore I wouldn't be afraid of using this plant, just don't eat the red berries, consume raw, and use with moderation, backing off with nausea or loose stools.