Nutritional Approaches To Bacterial Infections: A Healthy Immune System
Nutritional deficiencies can affect immune response and increase susceptibility to infection. In turn, infection further aggravates nutritional deficiencies by increasing metabolic demands, decreasing nutrient intake, or blocking absorption from the gut (Calder 2002; Scrimshaw 1997; Scrimshaw 2003). Nutritional and dietary supplements stimulate immune response and may result in fewer infections, particularly in the elderly and in malnourished, critically ill individuals (Chandra1999).
Some dietary supplements have been shown to enhance immune function.
Phytonutrients. Phytonutrients are plant-derived, naturally occurring compounds thought to have curative, preventative, and nutritive value (Balentine 1999; Craig 1999). The major immune-boosting components in fruits, vegetables, and herbs are flavonoids and carotenoids, which are antioxidants that protect cells from oxidative damage (Craig 1999; Craig 1999). Flavonoids have a number of powerful complementary and overlapping effects, including modulation of detoxification enzymes, stimulation of the immune system, reduction of platelet aggregation, modulation of cholesterol synthesis, reduction of blood pressure, and antioxidant and antibacterial effects (Craig 1999; Lampe1999). Carotenoids may boost the immune system to fight bacteria by increasing the number of white blood cells (Balentine1999; Craig 1999).
Alkylglycerols. Alkylglycerols are found in shark liver oil as well as cow, sheep, and human breast milk. They are thought to act as immune boosters against infectious diseases. They have no known adverse effects at relatively high dosages of 100 milligrams (mg) three times daily (Pugliese 1998). For more safety information on shark liver oil, especially for people with atherosclerosis, see the Safety Caveats section.
Whey Protein. Whey protein is a rich source of essential amino acids. Compared with other protein sources, whey contains a higher concentration of branched-chain amino acids, which are important for tissue growth and repair. Additionally, whey is rich in the sulfur-containing amino acids cysteine and methionine, which enhance the body’s antioxidant protection by bolstering synthesis of glutathione, an important free radical scavenger (Marshall 2004). Other constituents of whey include beta-lactoglobulin, lactoferrin, and immunoglobulins, which support the immune system (Anon 2008).
In addition to immune-boosting supplements, a number of nutrients have shown antibacterial activity, especially when it comes to inhibiting bacterial infection. While large-scale human studies have yet to be conducted on many antibacterial nutrients, the existing animal studies show considerable promise with these agents.
Bee propolis and honey. Before antibiotics, honey was used to treat bacterial wound infections (Lusby 2002; Miorin 2003; Molan 2002). Bee propolis has antibacterial and anti-inflammatory properties. In vitro laboratory studies have shown activity against TB, H. pylori, skin ulcers, and colitis (Boyanova 2003; Dobrowolski 1991; Grange 1990).
Bromelain. Bromelain (a digestive enzyme derived from the pineapple plant) has been used for centuries as a folk remedy for digestive problems and to promote wound healing. It has been proposed as a digestive aid and shown immunomodulatory properties (Engwerda 2001). In animal studies, bromelain has been effective against E. coli by disrupting the bacteria's ability to adhere to mucosal lining in the digestive wall (Mynott 1996, 1997).
Cranberry juice. Cranberry juice can be an effective therapy for bacterial urinary tract infections, both to manage infection and reduce recurrence (Fleet 1994; Kontiokari 2001). A study demonstrated conclusively that cranberry proanthocyanidins provoke disabling alterations in the fimbriae and other surface properties of the E. coli bacterium, vastly diminishing its capacity to attach specifically to the surface of the cells lining the urinary tract (Pinzón-Arango 2009).
The bacteriostatic effect of cranberry and its extracts have been well documented (Stothers 2001; Kontiokari 2001). In 2009, a group of researchers compared antibiotics head-to-head with daily supplements of cranberry extract in women suffering from recurrent infection (McMurdo 2009). Cranberry extract (500 mg) and antibiotics (100 mg trimethoprin) were shown to be almost equally effective in preventing urinary tract infections.
Hibiscus. Hibiscus sabdariffa contains a range of powerful compounds that prevent E. coli from adhering to the walls of the urinary tract. In a double-blind, placebo-controlled clinical trial, women taking hibiscus experienced a reduction in UTI’s (Allaert 2009). Sixty-one women participated in the 6-month study, and 59 women completed the entire study. All of them had a history of frequent UTI’s (more than four per year, including one or more in the three months prior to the start of the study). The women were randomly assigned to one of three groups and received a daily dose of 200 mg of hibiscus extract standardized to 90% polyphenols, 200 mg of hibiscus extract standardized to 60% polyphenols, or placebo. Compared to the control group, women taking the hibiscus concentrations experienced a 77% decrease in infections, as well as overall improvement in urinary comfort.
Oil of oregano. Oregano oil has been used for centuries in Far Eastern and Middle Eastern cultures to treat respiratory infections, chronic inflammation, urinary tract infections, dysentery, and jaundice. Laboratory studies in which the oil was applied directly to food-borne pathogens showed that oregano oil has strong antibacterial properties (Dadalioglu 2004). Medicinal oregano grows wild in the mountainous areas of Greece and Turkey. It has a high mineral content that enhances its therapeutic benefits, including calcium, magnesium, zinc, iron, potassium, copper, boron, and manganese. This oil is considered safe for humans and may be used in conjunction with antibiotics to fight bacterial infection (Preuss 2005).
Thyme. Thyme, another essential herbal oil, has shown antibacterial properties. For example, thyme has been demonstrated to inhibit many strains of E. coli, including E. coli 0157:H7 (Marino 1999). It has also been very effective in preventing the growth of Listeria (Faleiro 2005).
Ginger. The characteristic odor and flavor of ginger root come from a volatile oil composed of shogaol and gingerols. Gingerols have been investigated for analgesic, sedative, antipyretic, antibacterial, and gastrointestinal tract motility effects. They have been found to inhibit Gram-positive and Gram-negative bacteria (Chrubasik 2005; Mascolo 1989; Thongson 2004).
N-acetyl-cysteine. N-acetyl-cysteine (NAC) may help fight H. pylori infections, both because of its ability to interfere with the oxidant-inflammation connection, and also because of its potential to travel deep into the gastric mucous layer beneath which the organisms hide (Huynh 2004).
NAC markedly inhibits growth of H. pylori both in culture dishes and in live mice, helping to reduce the total load of organisms present (Huynh 2004). It also powerfully regulates gene expression in stomach lining cells, reducing hydrogen peroxide production induced by H. pylori, and decreasing activation of Nf-kB and subsequent release of inflammatory cytokines (Seo 2002; Kim 2007). In human trials, NAC improves eradication rates of H. pylori produced by standard treatment with antacids and antibiotics when given at doses of 1,200 mg per day (Zala 1994; Gurbuz 2005).
Enhancing Your Immune System While Fighting Bacteria
The nutrients vitamin A, beta-carotene, folic acid, vitamin B12, vitamin C, vitamin D, riboflavin, iron, copper, zinc, and selenium have both antioxidant activity and immunomodulating functions that affect the course and outcome of bacterial infections (Bhaskaram 2001; Meydani 2001; Murray 1997). In general, people taking multivitamin and multimineral supplements report significantly fewer infectious illnesses. In one small study, efficacy was highest in individuals with type 2 diabetes (Barringer 2003).
Glutamine. Glutamine helps build and maintain muscles, modulates pH, and contributes to a healthy digestive system (MacKay 2003). It is also an important precursor to glutathione, a natural antioxidant. Glutamine has been shown to help boost immune function through white blood cell respiration and production of messenger chemicals used by the immune system (Bistrian 2004).
Vitamin A. Low levels of vitamin A have been associated with increased susceptibility to bacterial infection, and vitamin A supplementation has been suggested to decrease days of work lost to infection (Aukrust 2000; Barringer 2003; Bhaskaram 2001). Vitamin A appears to be important in mucosal immune responses in the respiratory and gastrointestinal tracts (Cui 2000). The effect may be primarily from stabilizing the membranes of mucosal cells and enhancing white blood cell function (Molina 1996). Vitamin A has been studied in dosages up to 75,000 international units (IU) per day for up to 12 months (in the context of skin cancer) with no appreciable toxicity (Alberts 2004).
Vitamin E. Vitamin E improves immune function in the elderly. Supplementation with vitamin E (alpha-tocopherol) has been documented to increase levels of anti-inflammatory chemicals and decrease levels of pro-inflammatory proteins (Meydani 2001). Vitamin E enhances the immune system through its ability to protect immune cells from free-radical attack, which preserves membrane integrity and fluidity (Tengerdy 1990).
Zinc. Many studies have shown that zinc deficiency is associated with impaired immune function (Bogden 2004; Cuevas 2005; Cunningham-Rundles 2000; Stefanidou 2005). A combination of zinc and selenium may enhance immunity and protect against infections, especially in the elderly. A review article of published studies showed that elderly individuals taking modest doses of a multivitamin and multimineral dietary supplement containing zinc and selenium had fewer days on antibiotics and fewer infections than counterparts who did not take zinc-containing multivitamins or supplements (Chandra 1992).
Garlic. Crushed garlic has potent antibacterial effects (Ankri 1999; Cutler 2004; Jonkers 1999; Sovova 2002). It fights infection by enhancing immune cell activity and inhibiting bacteria and other microorganisms (Craig 1997; Harris 2001). The compound in garlic that produces antibacterial activity is known as allicin (Ankri 1999; Sovova 2002). Allicin is released when intact cells of a garlic clove are cut or crushed. There is evidence that garlic is effective against antibiotic-resistant strains of Staphylococcus species, pneumonia-causing bacteria, and antibiotic-resistant strains of H. pylori (Dikasso 2002; Sivam 2001; Tsao 2003).
Goldenseal. Goldenseal (a member of the buttercup family) has been used topically to treat eye and skin irritations and orally to treat infections (O'Hara 1998). Berberine, the main active ingredient in goldenseal, prevents bacteria from adhering to epithelial cells (Sun 1988), inhibits the intestinal secretory response of cholera and E. coli toxins, and normalizes intestinal mucous membranes after damage from cholera (Sack 1982).
Licorice. Licorice is derived from the root of the Glycyrrhiza species. Glycyrrhizin is converted by intestinal flora to glycyrrhetinic acid, which has immunomodulating activity. In laboratory studies, glycyrrhetinic acid has demonstrated powerful effects against H. pylori gastritis and ulcers (Chung 1998; Krausse 2004). Studies have shown that, in humans, adverse effects begin at daily dosages of 100 mg (Stormer 1993).
Lactoferrin. Lactoferrin (a component of whey) increases good microflora (such as Bifidobacterium bifidum) and decreases bad bacteria, resulting in a desirable intestinal flora environment that is essential for optimal health, immunity, and disease resistance. Lactoferrin is a powerful antimicrobial able to inhibit a wide range of pathogenic bacteria and other microbes (de Bortoli 2007; Wakabayashi 2009; Hayworth 2009; Bellamy 1992a; Bellamy 1992b). The mechanism appears to lie with lactoferrin’s ability to bind iron, as it is known to have an extremely high affinity for this metal (Artym 2010; González-Chávez 2009; Puddu 2009). It is referred to as hololactoferrin in its iron bound form and apolactoferrin in its iron-depleted form. Studies have found that the apolactoferrin form has the most powerful effects as an antimicrobial agent (León-Sicairos 2006; Norrby 2004; Griffiths 2004; Griffiths 2003).
Other organisms inhibited by lactoferrin include Gram-positive and Gram-negative bacteria, yeasts, and some intestinal parasites such as Vibrio cholerae, E. coli (Haversen 2000), Shigella flexneri, S. epidermidis, P. aeruginosa, and Candida albicans (Baldi 2005; Griffiths 2003; Kuwata 1998; Nikolaev 2004).
Lactoferrin may be especially useful as an adjuvant therapy for antibiotics. One study looked at the synergistic effect between lactoferrin and vancomycin. Researchers found that lactoferrin lowered vancomycin-resistance in some bacteria (Leitch 2001).
Probiotics. Probiotics are bacterial cultures contained in yogurt, buttermilk, cheese, kefir, sauerkraut, or dietary supplements that contain friendly bacteria (such as Lactobacillus, Bifidobacterium, Eubacterium, and Propionibacterium species) normally present on skin and in vaginal, urinary, and intestinal tracts. These bacteria are essential to the proper function of the vaginal, urinary, and digestive tracts (Bengmark 1998; Cunningham-Rundles 2000; Dani 2002).
Probiotics assist immune function by inhibiting harmful bacterial growth, promoting good digestion, maintaining proper pH, and enhancing immune function (Perdigon 1995). Probiotics produce bacteria-inhibiting substances (natural antibiotics) and prevent harmful bacteria from attaching to vaginal, urinary, and intestinal tract mucosal linings (Ochmanski 1999; Vaughan 1999). Probiotics have demonstrated an ability to suppress H. pylori in vitro (Cremonini 2001; Drouin 1999; Felley 2003; Johnson-Henry 2004; Wang 2004). They may be useful in preventing acute infectious diarrhea (Marignani 2004), urinary tract infections (Kontiokari 2003; Reid 2002), and restoring vaginal flora (Andreeva 2002).
Antibiotics often destroy friendly bacteria on skin and in urinary, vaginal, and intestinal tracts. Probiotics can be used to recolonize and restore natural floral balance in organ and body systems after antibiotic treatment (Fooks 2002; Guarner 2003; Shi 2004).
Tea catechins. Tea (black, green, or oolong) is a good source of free-radical scavenging antioxidants (Trevisanato 2000). Other infection-fighting chemicals were heightened in cells of tea drinkers, leading researchers to conclude that drinking tea primed the immune system to fight infection (Bukowski 1999; Kamath 2003).
These results have been borne out in many clinical studies. Elements of tea, called catechins, have been widely studied for their ability to prevent bacterial infection. One such study examined catechins' ability to prevent infection in the prostate gland in rats. This condition, known as chronic bacterial prostatitis, is extremely common in men. Researchers found that tea catechins were able to reduce both bacterial growth and inflammation in the rats' prostate glands. Moreover, the catechins worked well as an adjuvant therapy for ciprofloxacin, the standard antibiotic treatment for this condition. Researchers suggested that tea catechins, which have shown additional antibacterial effects and synergistic properties with antibiotics, be considered to help manage chronic bacterial prostatitis (Lee 2005).
In another interesting study, researchers infused plastic film with tea catechins, then tested this surface for antibacterial properties. They found that the catechin-infused film was significantly resistant to bacteria such as E. coli and suggested that implants and catheters made from catechin-infused plastic might be able to help reduce infection during invasive procedures (Maeyama 2005).
Catechins are thought to boost immunity by enhancing resistance to infection and selectively modulating the formation of cytokines, which are associated with inflammation, among other things. Researchers have also hypothesized that hydrogen peroxide generated by the catechins may also be responsible for its antibacterial properties (Arakawa 2004). In a laboratory study of immune cells taken from heavy smokers, tea catechins were shown to help the immune cells recover their function (Yamamoto 2004).
Beta-glucan. Numerous substances including polysaccharides, lymphokines, and peptides activate the defensive properties of macrophages. A polysaccharide called beta-glucan not only enhances macrophages’ ability to recognize and subdue microbial invaders, but also increases their ability to communicate with other cellular defenders of the immune system.
At Brigham and Women’s Hospital in Boston, Massachusetts, researchers found that the compound enhances antibiotic efficacy in rats infected with antibiotic-resistant bacteria. Rats with intra-abdominal sepsis due to antibiotic-resistant bacteria—namely Escherichia coli or Staphylococcus aureus—were given a type of beta-glucan (PGG glucan) that enhances the function of macrophages and neutrophils. Researchers looked at beta-glucan’s ability to work in partnership with antibiotics to decrease mortality of the rats. “Results of these studies demonstrated that prophylaxis with PGG glucan in combination with antibiotics provided enhanced protection against lethal challenge with Escherichia coli or Staphylococcus aureus as compared with the use of antibiotics alone,” wrote the researchers (Tzianabos 1996).
Canadian scientists have demonstrated that beta-glucan confers protection against deadly anthrax infection in animals. For example, in mice that received beta-glucan for one week prior to infection with anthrax bacteria, survival increased from 50% to 100%. When beta-glucan was administered only after infection had occurred, survival rates increased from 30% to 90% in the treatment groups. “These results demonstrate the potential for [beta-glucan] immune modulators to provide a significant degree of protection against anthrax,” the researchers concluded (Kournikakis 2003). Similar results against other pathogens have been reported by other researchers (Kernodle 1998; Onderdonk 1992; Hetland 1998).
Andrographis. Healers in Asia and India have long prescribed the bitter herb Andrographis paniculata for the treatment of ailments ranging from infections and inflammation to colds and fevers (Ji 2005). Researchers have isolated a number of the herb’s active ingredients. Chief among these are andrographolides, which are phytochemicals that are believed to exert their effects, in part, on tissues of the blood cell-producing bone marrow and/or spleen.
Hyperimmune egg extracts. Agricultural scientists long ago discovered that they could immunize hens against germs that threaten humans. This immunity was then passed on by the hen to her egg (Dias da Silva 2010; Dean 2000; Cama 1991). Concentrated protein extracts from those so-called “hyperimmune eggs” confer some immunity to humans who consume them (Fujibayashi 2009; Sarker 2001).
Patients with cystic fibrosis (CF) are especially at risk for colonization of their lungs with Pseudomonas aeruginosa (PA), an organism that thrives in overly-viscous mucous secretions. PA infection is in fact the major cause of death and disability in cystic fibrosis patients (Kollberg 2003). Among cystic fibrosis patients who gargled with a hyperimmune egg preparation from hens immunized against PA, none became chronically colonized with the organism, while 24% of control subjects did (Kollberg 2003).
Hyperimmune egg may also be effective for other less serious, but more common respiratory tract infections. There was a reduction in symptoms among people with both acute and chronic bacterial sore throat when they used a hyperimmune egg-containing throat spray, compared with placebo-treated subjects (Xie 2004).