Targeted Nutritional Therapies
After infection, viruses causing the common cold multiply rapidly. While most people wait until their symptoms become unbearable, then use an over-the-counter medication, Life Extension recommends aggressive action when the viral count is still relatively low and symptoms are mild.
Vitamin D. Evidence suggests vitamin D has a significant role in the regulation of the human immune system, and may reduce the risk of certain bacterial and viral infections (Beard 2011; Grant 2010). Theoretically, vitamin D supplementation may produce a sufficient amount of cathelicidin (a naturally occurring antimicrobial and antiviral) to cure viral respiratory infections such as the common cold (Cannell 2008; Barlow 2011). Furthermore, data show that higher vitamin D levels are associated with a decreased risk of contracting a seasonal viral infection (Berry 2011; Cannell 2011). Life Extension recommends an optimal 25-hydroxyvitamin D blood level of between 50 and 80 ng/ml.
Vitamin C. Evidence shows that vitamin C augments several aspects of the immune system and helps defend against infections (especially viral infections) (Ely 2007; Holt 2010; Heimer 2009; Khalid 2011). Vitamin C enhances the production and action of white blood cells; for example it increases the ability of neutrophils (a type of white blood cell) to attack and engulf viruses (Heimer 2009; Jariwalla 1996; Anderson 1984). Vitamin C has been shown to reduce the chances of catching a cold, and may reduce cold duration (Holt 2010; Hemila 2011). Upon review of clinical data from 2 studies, researchers found that using vitamin C (1000 mg) plus zinc (10 mg) during a cold could reduce runny nose symptoms by up to 27 % over 5 days of treatment compared to placebo (Maggini 2012).
Zinc – Zinc helps maintain a healthy immune system, and zinc deficiency has been linked to significant immune impairment and susceptibility to infections (Roxas 2007; Maggini 2012). Unfortunately, zinc deficiency is a common problem affecting approximately 2 billion people worldwide, even many people in Western populations. Correcting zinc deficiency through supplementation has been shown to bolster aspects of the immune system involved in fighting viral infections (Maggini 2012; Sandstead 2010; Pae 2012). Zinc's antiviral properties may come from its ability to prevent the rhinovirus from attaching to cells in the nasal passages. In addition, zinc has been shown to prevent viral replication, reduce histamine release, and inhibit the production of other inflammatory mediators (Singh 2011).
A comprehensive review concluded that zinc supplementation was associated with a significant reduction in the duration and severity of the common cold (when administered within 24 hours of onset of symptoms). It was also found that zinc supplementation over 5 months was helpful for preventing the common cold (Singh 2011). Clinical trials of zinc lozenges (as zinc gluconate and zinc acetate) have shown benefit in reducing the duration of colds when taken at doses of 13-23 mg every 2-3 waking hours (Singh 2011; Prasad 2000 ).
DHEA. Dehydroepiandrosterone (DHEA) is a steroid hormone synthesized by the adrenal gland. Research has revealed that DHEA possesses powerful immune-enhancing and antiviral properties, and can enhance resistance to many different experimental infections (Romanutti 2010; Torres 2012; Kuehn 2011; Roxas 2007). DHEA accomplishes this in part by modulating several aspects of the immune system. For example, administering 50 mg of DHEA daily to an elderly population resulted in an increase in natural killer cell activity, a 62% increase in B cell activity and a 40% increase in T cell activity, all of which are important for defending against infectious pathogens (Roxas 2007).
DHEA supplementation is likely to be especially important among the aging and elderly, since DHEA levels decline sharply with age (Roxas 2007; Khorram 1997).
Melatonin. Melatonin is a hormone produced in the brain and the gut. It helps regulate the sleep-wake cycle and is a powerful antioxidant. Research indicates that melatonin helps combat many types of viral infections (Srinivasan 2012; Arushanian 2002; Boga 2012). For example, melatonin appears to "prime" the immune system by interacting with specialized immune cells called "T-helper cells", allowing for a more efficient immune response against pathogens. Furthermore, melatonin administration is also associated with an increased production of antibodies (Bonilla 2004).
Melatonin's role as an antioxidant may be helpful during a cold as well, since most viral infections are associated with high amounts of oxidative stress (Boga 2012). This may be especially true for elderly populations, since these patients frequently experience age-related impairment of the immune system, which coincides with declining melatonin concentrations (Srinivasan 2005).
Astragalus membranaceus. Astragalus membranaceus is a Chinese herb that contains a number of immune-stimulating ingredients such as polysaccharides, flavonoids, trace minerals, and amino acids. While it has been traditionally used to treat colds and flu as well as for increasing stamina and overall vitality, much of the research performed on Astragalus membranaceus is focused on its application for treating immune deficiency conditions (Roxas 2007; AMR 2003). In a clinical study comparing various natural products (i.e., echinacea, astragalus membranaceus, and licorice), Astragalus membranaceus demonstrated the strongest ability to activate immune cells (Roxas 2007).
Elderberry. Elderberry, also known as Sambucus nigra, has been used for its medicinal properties since at least 400 BC (Krawitz 2011; Roxas 2007). The purplish-black fruits of the elderberry plant are a rich source of antioxidants, and have long been considered a folk remedy for the treatment of influenza as well as the common cold (Ozgen 2010; Zakay-Rones 2004). Even today, elderberry extracts are commonly employed as an alternative to conventional drugs for the management of a variety of viral infections and are recognized as supportive agents against common cold (Krawitz 2011). Researchers believe that elderberry fights colds by activating white blood cells that engulf pathogens. The German Commission E (a therapeutic guide for the safety and efficacy of herbal products) has identified the constituents of elderberry as effective for the relief of colds (Roxas 2007).
Garlic. Garlic (i.e., allium sativum) has been traditionally used for both its culinary and therapeutic properties (Lissiman 2012). A clinical survey found that garlic is one of the most common herbs used for its medicinal properties including for the treatment of colds, flu, and cough (Zhang 2008). When raw garlic is chopped or chewed, it releases an active organo-sulfur compound called allicin, which has demonstrated antiviral activity against rhinovirus and a variety of other pathogens (Nahas 2011). While studies evaluating the use of garlic/allicin for the treatment of the common cold are lacking, evidence suggests it may be useful for the prevention of such infections (Nahas 2011). For example, one clinical study demonstrated that an allicin-containing garlic supplement taken once daily (over a 12-week period) was associated with 65% fewer colds than the placebo group (24 vs. 65). When compared to placebo, garlic/allicin supplementation was also linked to 70% reduction in symptom duration (~ 1.5 vs. 5 days) (Josling 2001).
Andrographis. Andrographis paniculata has been effectively used among Asian cultures for the treatment of colds for centuries (Chandrasekaran 2009; Ozolua 2011; Ji 2005; Akbar 2011; Valdiani 2012). It is reported to have anti-inflammatory, blood pressure lowering, antiviral, and immune-stimulant properties (Yang 2010). A 2009 study found that an extract of Andrographis enhanced immune function as well as reversed drug-induced immunosuppression (Naik 2009). Accumulating evidence suggests that Andrographis paniculata is effective as an alternative treatment option for the common cold (Coon 2004; Poolsup 2004; Kligler 2006). For example, a 2010 study found that a standardized extract of Andrographis paniculata was more than twice as effective as placebo in reducing symptoms of upper respiratory tract infections (Saxena 2010). Preliminary evidence suggests that Andrographis paniculata may be effective for the prevention of colds as well (Coon 2004).
Lactoferrin. Lactoferrin is an iron-binding protein found in milk. It is a powerful immune modulator and has shown marked ability to fight bacteria, fungi, protozoa, and viruses (Roxas 2007; Orsi 2004; Lonnerdal 2009). Laboratory studies reveal lactoferrin inhibits viral infection by interfering with the ability of certain viruses to bind to cell receptor sites and prevents entry of viruses into host cells (Waarts 2005; Berlutti 2011). In addition, lactoferrin may be beneficial for alleviating the symptoms or complications of viral infections like the common cold, because it suppresses free radical-mediated damage (Roxas 2007).
Beta-glucan. Beta-glucans are naturally occurring glucose polymers that constitute the cell walls of certain plants and pathogenic agents (Akramiene 2007). These polysaccharides have been shown to increase host immune defense, and are associated with enhancing macrophage and natural killer cell function (Pence 2012; Akramiene 2007). Beta glucans also appear to mitigate the symptoms of the common cold. The Montana Center for Work Physiology and Exercise Metabolism examined beta glucans' ability to mitigate upper respiratory infections in a single blind, randomized trial in 2008. Participants who consumed beta-glucans had 23% fewer upper respiratory tract infections, compared to the group taking a placebo (PRNewswire 2008).
Probiotics. Probiotics are defined as living microorganisms (i.e., bacteria and fungi) that confer a health benefit to the host when administered in adequate amounts (Gilliland 2001; MacDonald 2010). Clinical studies suggest that certain probiotics may help prevent viral respiratory tract infections such as the common cold by enhancing the immune system. Some probiotics are associated with a reduction in severity and duration of symptoms caused by common upper respiratory tract infections (de Vrese 2008; MacDonald 2010; Wolvers 2010; Vouloumanou 2009; Baron 2009; Leyer 2009). Probiotics may be useful for managing infectious diseases because of their potential for stabilizing the micro-flora of the gut, enhancing resistance against pathogenic colonization, and modulating immune functions (Wolvers 2010; Kimmel 2010; Baron 2009). A 2011 clinical study found that a probiotic lactobacilli was able to strengthen the body's immune defense against viral infections and reduce the risk of acquiring the common cold (Berggren 2011). Furthermore, the consumption of yogurt fermented with Lactobacillus augmented natural killer cell activity and reduced the risk of catching common cold infections among the elderly (Makino 2010).
Echinacea. Echinacea is an herb that was first utilized for its medicinal value by the Native Americans in the treatment of cough, sore throat, and tonsillitis (Caruso 2005). Today, echinacea represents one of the most popular herbs used for the treatment and prevention of upper respiratory tract infections (like the common cold) in both European and American markets (Tierra 2007; Woelkart 2008; Toselli 2009). Clinical evidence shows that echinacea has beneficial effects on the common cold, including reduced severity and duration of cold symptoms, as well as increases in monocytes, neutrophils, natural killer (NK) cells, and total white blood cell count (Roxas 2007). A 2010 clinical study found that a standardized extract of E. purpurea was able reduce the risk of common cold among athletes (Ross 2010).
Honey. Honey has been used since ancient times as a cough and cold remedy in some countries (Pourahmad 2009). Studies have shown that honey possesses antimicrobial properties and helps combat infection in a variety of clinical settings (Al-Waili 2011). Clinical trials have compared the efficacy of honey to that of placebo and several conventional medicines for relieving symptoms of the common cold (Pourahmad 2009). Evidence suggests that honey can relieve symptoms of the common cold in adults and children more effectively than some, but not all, conventional medicines (Heppermann 2009; Paul 2007; Oduwole 2012; Cohen 2012).