Eating the right foods can boost your immune response to help defeat invading bacteria and pathogens that can cause infection and disease. A varied diet will likely provide you with all the nutrients your body needs, but it's good to know which specific foods are the best natural bacteria killers.
Although no specific food can prevent an infection, eating a variety of antioxidant-rich foods will strengthen your immune system. This may lessen your chance of infection, whether it be from a wound or a more serious condition, such as an infection of the respiratory tract from a cold.
What Causes Infection?
Your body is made up of trillions of beneficial bacteria that live on your skin and in your gut and mucous cells. Some bacteria break down food into absorbable nutrients, synthesize vitamins, destroy disease-causing cells and support immune function, according to the National Academies.
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However, other microorganisms are responsible for infections. Germs in the form of viruses, infectious bacteria and other microbes, known as pathogens, can enter your body through your mouth, eyes, nose or open wounds. These microorganisms may produce toxins. They can also multiply and spread throughout your body.
In response to these invading pathogens, your body's immune system springs into action. The immune system is a complex and sophisticated network of specialized cells and tissues, organs, proteins and chemicals that work together to protect your body against dangerous infections.
A close relationship exists between your overall nutritional health and the proper functioning of your immune system. Your ability to fight infection and disease depends on your immunity, so it's important to eat foods that fight infection and help strengthen your natural defenses.
Foods Rich in Antioxidants
Certain vitamins, minerals and phytonutrients in food have a role in supporting and strengthening your immune system. These are called antioxidants and protect your cells from the effects of free radicals.
Free radicals are molecules produced as by-products of metabolic processes, such as when your body breaks down food, or from environmental factors, such as exposure to tobacco smoke and radiation.
Vitamin C is an important physiological antioxidant and may even help regenerate other antioxidants in your body, including vitamin E, according to the National Institute of Health. Low levels of vitamin C can result in impaired immunity and higher susceptibility to infections, reports a November 2017 review in the journal Nutrients. As the researchers note, this nutrient may both prevent and treat respiratory and systemic infections.
Another review published in Nutrients in March 2017 noted that vitamin C levels in white blood cells are 10 times higher than in plasma, which may indicate the functional role of the vitamin in immune function. Authors report that large animal studies concluded that vitamin C may help prevent, shorten and alleviate diverse infections, and suggest there is evidence that vitamin C has similar effects in humans.
This nutrient is known for its association with the common cold. Although vitamin C will not prevent you from succumbing to the viral infection of a cold, a meta-analysis of nine trials, published in BioMed Research International in July 2018, found that vitamin C supplementation may shorten the duration and severity of the illness.
The best vitamin C food sources, according to the USDA, include:
- Red bell pepper
- Kiwi fruit
Vitamin E is another one of the natural healing foods for diseases. Its antioxidant properties can protect your cells from oxidation and thereby contribute to preventing problems from infection. This nutrient may also have an effect on respiratory tract infections.
A study published in the European Journal of Clinical Nutrition in January 2017 assessed the dietary intake of 1,533 Swedish adults for nine months and concluded that the intake of vitamin E, as well as vitamin C, had an inverse association with the incidence of upper respiratory tract infection in women.
The top foods high in vitamin E that can help to ward off infection, as reported by the USDA, are:
- Sunflower seeds and almonds
- Olive oil
Carotenoids, which include beta-carotene and lycopene, are also important for maintaining your immune system. These substances are responsible for the bright pigments in many fruits and vegetables. Think colorful when choosing powerful antioxidant-rich carotenoid foods. The USDA lists the following foods as being high in this nutrient:
- Sweet potatoes
- Dark leafy greens
- Butternut squash
- Red bell peppers
Read more: 8 Foods That Boost Your Immune System
Foods That Support Wound Healing
Many foods have antimicrobial and antibacterial properties that may help accelerate wound healing by reducing oxygen molecules and inhibiting the reproduction of bacteria that can lead to skin infections.
Garlic is among the foods that fight infection and has been used medicinally for centuries to heal wounds. The beneficial effects come from an enzyme in garlic called allicin, according to the Linus Pauling Institute.
Allicin is released from garlic when you crush or chop it. It is responsible for the distinct taste and smell of garlic. This compound breaks down to form a variety of organosulfur compounds that exert infection-fighting attributes, making them natural bacteria killers.
Read more: Which Is Healthier, Raw or Cooked Garlic?
Zinc also has antimicrobial and antibacterial properties that play a role in wound healing. In addition to supporting the immune system, zinc is a cofactor for many enzymes required for cell membrane repair, the production of collagen, protein synthesis and cell proliferation, all of which are essential for tissue regeneration, according to the National Institutes of Health (NIH).
This mineral helps your skin stay healthy, and a deficiency may cause skin ulcers and delayed wound healing, which could give bacteria the opportunity to invade your tissue and cause infection.
According to the NIH, foods that contain zinc may decrease your susceptibility to infection, and include:
- Red meat and poultry
- Fortified breakfast cereals
- Whole grains
Antibacterial Herbs and Spices
Many commonly used herbs and spices contain antimicrobial and antibacterial compounds that help fight infection. Some of these include cloves, oregano, thyme, cinnamon and cumin. A review published in the International Journal of Molecular Sciences (IJMS) in June 2017 summarized the significance of spices in relationship to their potential use for food preservation and treatment of some infections. These include:
Ginger: Gingerol, which gives ginger its pungent taste, is the key antifungal and antimicrobial ingredient in ginger. The review authors reported that ginger also exhibited antibacterial activity against all tested pathogens, including those causing oral infections. Ginger, with honey, is commonly used as a remedy for throat congestion and infection.
Cloves: The main active antimicrobial component in cloves is eugenol. Cloves help fight infection as demonstrated by their use in antiseptics to treat periodontal disease and infection, according to the IJMS.
Oregano: The major antimicrobial components in oregano are carvacrol and thymol. The IJMS review reported these agents to be effective against some bacterial infections, such as staphylococcus and salmonella.
Thyme: Thymol is the primary active antimicrobial compound in thyme. Evidence from the June 2017 IJMS review noted that thyme oil had a high antibacterial effect against 35 bacterial strains tested.
Cinnamon: The antimicrobial properties of cinnamon make it a health-promoting agent to treat inflammation, intestinal disorders and urinary infections, as reported in the IJMS study.
- National Academy of Science: "What You Need To Know About Infectious Disease"
- National Institutes of Health: "Vitamin C"
- Nutrients: "Vitamin C and Infections"
- BioMed Research International: "Extra Dose of Vitamin C Based on a Daily Supplementation Shortens the Common Cold: A Meta-Analysis of 9 Randomized Controlled Trials"
- MyFoodData: "Nutrition Comparison of Oranges, Strawberries, Kiwifruit, Sweet Red Bell Peppers, and Guavas"
- MyFoodData: "Top 10 Foods Highest in Vitamin E"
- MyFoodData: "Top 10 Foods Highest in Beta Carotene"
- Linus Pauling Institute: "Garlic and Organosulfur Compounds"
- National Institutes of Health: "Zinc"
- International Journal of Molecular Sciences: "Antibacterial and Antifungal Activities of Spices"
- European Journal of Clinical Nutrition: "Intake of Vitamin C, Vitamin E, Selenium, Sinc and Polyunsaturated Fatty Acids and Upper Respiratory Tract Infection—a Prospective Cohort Study"
- Nutrients: "Vitamin C and Immune Function"
- Antioxidants: "Carotenoids—Antioxidant Properties"
Is this an emergency? If you are experiencing serious medical symptoms, please see the National Library of Medicine’s list of signs you need emergency medical attention or call 911.