Foods with natural antiviral properties include garlic, onions, honey, dandelion greens and a variety of sea vegetables. Natural medicine practitioners have used these foods for centuries, as it is believed that each one can guard against infection and, in some cases, even help individuals recover from illness when these foods are used in organic therapies. Beverages believed to also have natural antiviral properties include herbal teas, in particular peppermint, lemon balm, green and white teas.

Garlic is amongst the most widely regarded of all antiviral foods. Many antiviral supplements contain garlic extract as a primary ingredient used to fight harmful bacteria. Research indicates that garlic is effective as a natural antiviral due to the presence of sulfur naturally found in garlic cloves.

Another natural antiviral food that has been widely touted by natural medicine practitioners is onions. In their natural state, onions also contain high concentrations of sulfur, which is deemed to be useful as a natural therapy against viral infections when the vegetable is eaten raw. While both onion and garlic are known for very pungent odors and a spicy taste, scientists believe that humans actually developed a taste for such foods because their natural antiviral properties can kill dangerous microbes that developed in spoiled foods before refrigeration techniques were discovered.

When honeybees combine their own natural secretions with plant resins collected while foraging for food, they produce a substance known as propolis used to build and repair hives. This substance also happens to have natural antiviral properties. Considered to be the original creator of Western medicine, the ancient Greek philosopher and physician Hippocrates used honey as a natural medicine to treat various conditions. Often, honey is combined with garlic in certain natural medicine therapies.

Sea vegetables, such as certain types of sea algae and seaweed, are also believed to have a natural antiviral effect. It is believed that this is due to the presence of sulfated polysaccharides contained in sea vegetables. Like garlic and onions, these particular polysaccharides contain sulfur.

Green tea, black tea and white tea all contain tannins, which have a natural antiviral effect. Also, peppermint tea is believed to contain antiviral properties. Research performed using raw peppermint has discovered that peppermint effectively destroys certain viral and bacterial strains. Another member of the mint family, lemon balm, has a similar antiviral effect due to the tannins it naturally contains.