Although plenty of prescription antibiotics are available, the threat of antibiotic resistance has sparked interest in foods that have antibacterial properties. To boot, consumers seem to be interested in minimally processed foods with antibacterial effects—so a market for these products exists.
The natural pathogen-fighting benefits of garlic and ginger are fairly well known, but let’s take a look at some other foods and spices that can offer the same immunoprotection.
Like people, plants can also get sick. For instance, when threatened, grapes will release organic compounds to defend their vines against phytopathogens.
The phenolic compounds found in wine and grape products can offer some protection against:
- Iatrogenic pathogens (eg, Helicobacter pylori and Klebsiella pneumoniae)
- Foodborne pathogens (eg, Escherichia coli, Listeria monocytogenes, Salmonella enterica, and Staphylococcusaureus)
- Oral pathogens
- Viruses (eg, adenovirus, hepatitis virus, and rotavirus)
- Parasites (eg, Eimeria tenella and Trichomonas vaginalis)
- Fungi (eg, Candida albicans)
- Microbial toxins (ochratoxin A and Shiga toxin)
Water-soluble peptide extracts (WSPEs) are bacterial peptides that are released from dairy products like yogurt and possess antimicrobial properties.
“The WSPE exhibited stronger inhibitory activity against gram-negative compared with gram-positive bacteria. In addition, the WSPE inhibited proliferation of HT29 human colon cancer cells. Generation of inhibitory peptides against bacteria and HT29 human colon cancer cells improved with [pineapple peel powder] supplementation of yogurt. However, activities reduced substantially after [gastrointestinal] tract digestion. Taken together, the incorporation of [pineapple peel powder] and probiotics in yogurts offers new opportunities in the development of novel functional foods, and this approach could lead to the development of novel bioactive peptides having antibacterial and anticancer activity,” concluded the authors of one study investigating the antibacterial effects of yogurt.
If interested in an exotic spin on healthy foods, consider moringa, also known as the horseradish tree. Like the turnip, moringa is a vegetable of the Brassicales order. It is most commonly found in India and Africa, and is used in food preparation as a spice.
Interestingly, moringa has been shown in several studies to have greater antibacterial activity against gram-positive bacteria, such as Staph., than against gram-negative species, such as E. coli and Pseudomonas.
Cinnamon extract is mostly made up of cinnamaldehyde and eugenol, which are compounds that attack respiratory and gastrointestinal pathogens. According to some studies, cinnamon may also protect against infection from H. pylori; however, there isn’t enough evidence to support cinnamon as a form of treatment for H. pylori-induced gastric ulcers.
When boiled or ground into a powder, turmeric can be used to create yellow or orange coloring for food or skin cosmetics, and offers a distinct taste to a variety of Indian and Middle Eastern dishes. This member of the ginger family is well known for its anti-inflammatory health benefits—but did you know that turmeric has antimicrobial properties as well? In mechanistic studies assessing minimum inhibitory concentrations for various pathogens, turmeric demonstrated antimicrobial effects against a gamut of bacteria. Turmeric is so effective that it has even been considered as a candidate to impregnate clothes for antimicrobial benefit. Moreover, it may synergize with current antibiotics, including ampicillin, and thus enhance treatment efficacy.
Cranberry juice and supplements
Pretty much everyone has heard that cranberry juice is effective against urinary tract infections (UTIs). Indeed, cranberry juice may prevent the adherence of bacteria to uroepithelial cells, and suppress inflammatory responses due to infection. Researchers have shown that cranberry juice not only helps mitigate UTIs but may be of use as UTI prophylaxis.
However, cranberry juice may not be effective in all populations, including those at the highest risk of developing UTIs. Additionally, it’s unclear how much cranberry juice is needed to prevent or fight UTIs, and the amount needed may not be cost effective.
Furthermore, there is some debate as to whether cranberry juice or cranberry capsules/supplements provide the greatest defense against infection. In a 2015 study, for instance, taking cranberry capsules lowered the risk of UTIs by 50% in women who had catheters in place while undergoing gynecological surgery.
According to Timothy Boone, MD, PhD, chairman, Department of Urology, Houston Methodist Hospital, Houston, TX, who commented on the study, “Cranberry juice, especially the juice concentrates you find at the grocery store, will not treat a UTI or bladder infection. It can offer more hydration and possibly wash bacteria from your body more effectively, but the active ingredient in cranberry is long gone by the time it reaches your bladder.”
He added: “It takes an extremely large concentration of cranberry to prevent bacterial adhesion…In this study, [the researchers] took the cranberry itself and put it in a capsule—the equivalence of drinking 28 ounces of cranberry juice. As you can see, it takes a large amount of pure cranberry to prevent an infection.”
Echoing the results of the 2015 study are those from a more recent study published in Current Pharmaceutical Biotechnology, in which researchers supported the use of cranberry supplements in women for UTIs:
“Additional well-designed, double-blind, placebo-controlled clinical trials that use standardized cranberry products for long study periods are strongly recommended in order to determine the efficiency of cranberry on the prevention of UTIs in susceptible populations. At present, cranberry supplementation can safely be suggested as complementary therapy in women with recurrent UTIs.”
You’ve likely heard that honey fights germs. But how exactly?
For thousands of years, people have used honey as a wound dressing. In recent years, researchers have shown that honey is much more than a saccharine syrup. It contains various bioactive compounds that aid with healing.
Different types of honey vary in their antibacterial properties. Most honeys contain hydrogen peroxide, which is antibacterial, but catalyzed and inactivated by blood and wound tissue. Often used in wound dressing, manuka honey contains methylglyoxal, which is not inactivated by the body. Manuka honey can be diluted by wound exudates and still inhibit the growth of bacteria.
Honey also potentially promotes immune response, tissue growth, inflammation suppression, and autolytic debridement.
With the antibiotic drug pipeline drying up, few antibiotics have been released recently. This lack of innovation has turned interest toward natural sources of antibacterial goodness. As Hippocrates said, “Let food be thy medicine.”