The time to boost your immune system is now, folks.

Now that fall is officially here, it’s time to start worrying about contracting seasonal ailments if you haven’t already. Peak flu season begins in November, and the time to build up immunity is now. Aside from getting proper vaccination (The Centers for Disease Control and Prevention recommend getting vaccinated before October ends), the best way to keep yourself well is maintaining a healthy lifestyle and strong immune system. Getting enough sleep, avoiding stress, and regularly exercising will keep your body in check, but eating right can also deter illness. And if you’re going to eat right, that means you need to stay away from eating wrong.

One point to clarify: You can’t contract the cold or flu through ingestion. These respiratory viruses spread through the air and eventually land on objects, where they can last for up to two days. People who breathe in contaminated air or touch their eyes, mouth, or nose after contacting contaminated objects may contract the cold or flu, depending on the virus’ state and their own immunity.

Unless you suffer from an autoimmune disorder like Celiac disease, “there’s not a food that you take that’s going to suppress your immune system,” says Dr. Amesh Adalja, infectious disease specialist and senior scholar at the Johns Hopkins Center for Health Security and Fellow of the Infectious Diseases Society of America. “Good nutrition with the appropriate amounts of vitamins and elements are important for immune system function.”

However, excessive alcohol, processed food, and items that are high in simple sugar promote inflammation in the body. When that happens, the body shifts its focus to fight the inflammation, according to Dr. David Barzyck, a Louisiana-based chiropractor with more than 100 hours of post-graduate study in neurology. In other words, infection distracts your body, and that makes you more susceptible to illness. Barzyck adds that most illnesses start with inflammation. Additionally, too much cortisol, a stress hormone that’s found in caffeine, can also lower immune response, so you might want to hold off on that third or fourth cup of coffee. “What we eat affects how we feel and how our bodies operate,” says Dr. Janette Nesheiwat, a medical news expert specializing in family and ER medicine. In addition to the items mentioned above, Nesheiwat advises avoiding frozen foods and premade soups, which are often loaded with sodium and preservatives.

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While it’s impossible to completely cut germs out of your life, washing your hands with soap and warm water is a huge help, especially if you frequently touch your face or find yourself around anyone who might be sick.

“People do not practice hand hygiene enough,” Adalja says. “Basic hygienic practices coupled with flu vaccination go a long way to eliminate the spread of respiratory viruses, as well as some gastrointestinal viruses.”