Botanicals for immune boosting

Outside of the fungi and yeast, there are also botanicals with beneficial polysaccharides, as well as many other powerful compounds to bolster immune function. One of the best-known entries in this area is Echinacea, the genus for several plants, including E. purpurea, E. angustifolia and E. pallida. It may activate lymphocytes to scavenge for cellular debris and bacteria, and enhance cell-mediated immunity.

In vitro studies have shown E. purpurea extract upregulates dendritic cell activity,³⁹ while also modulating macrophage immune response.⁴⁰ A trial out of Iowa State University, Ames, examined the impact of E. angustifolia, E. pallida and E. purpurea extracts on immune parameters in mice.⁴¹ All three species worked to increase antibody response and altered cytokine production, increasing INF-alpha but inhibiting the release of TNF-gamma and IL-1beta. Further, E. angustifolia and E. pallida exerted higher T cell proliferation and increased production of IL-4 and IL-10, suggesting these species have more anti-inflammatory activity.

Further, a polysaccharide in Echinacea (arabinogalactan) is reported to increase interferon, tumor necrosis factor and IL-1 production through stimulation of macrophage activity. A study out of Southwest College in Arizona found extracts of E. purpurea and E. angustifolia combined with larch arabinogalactan (LAG), extracted from Larix occidentalis, increased production of complement properdin, which is an indicator of immune system stimulation.⁴²

On its own, LAG is a rich source of polysaccharides and dietary fiber, which can increase the production of short-chain fatty acids in the gut, while also working to stimulate NK cell cytotoxicity.⁴³ In fact, researchers from McGill University, Montreal, looked at the in vivo impact of LAG on NK cells and splenocytes in mice.⁴⁴ Administration of LAG was found to induce a range of cytokines and impact monocyte production.

Another source of arabinogalactan polysaccharides, as well as flavonoids, is Tinospora cordifolia, an Indian botanical traditionally used as an adaptogen. In vitro work suggests an extract from the stem of the plant modulates levels of cytokines and nitric oxide (NO), protecting macrophages from inflammatory challenges.⁴⁵ The efficacy of a specialized extract of T. cordifolia (as Tinofend®, from Verdure) in allergic rhinitis was tested in a randomized, placebo-controlled, double blind trial in India.⁴⁶ After an eight-week intervention, subjects who received the botanical extract had significant decreases in symptoms of allergic rhinitis, with decreased neutrophil count in nasal smear.

Also from India comes Andrographis paniculata, an extremely bitter herb traditionally used to treat infections. Indian researchers reported in animal studies, A. paniculata enhances the secretion of IL-2 and IFN-gamma by T cells, inhibiting tumor growth and increasing life span.⁴⁷ Further research has shown the extract can enhance antibody response when administered with vaccine⁴⁸ and inhibit viral replication.⁴⁹

Curcumin, the primary curcuminoid extracted from the botanical turmeric, has been used for centuries in India and China, and evidence is mounting that it exerts strong antioxidant, anti-inflammatory and immunomodulatory activities, impacting humoral and cell-mediated immune function.⁵⁰ Studies have shown curcumin does not impair NK cell function, even as it enhances the proliferation potential of T cells.⁵¹ It also may help to prevent overstimulation of dendritic cells;⁵² however, the effect appears to be specific to hydroethanolic extraction, rather than lipophilic extraction.⁵³

A Chinese adaptogenic and immune-enhancing botanical, Astragalus membranaceous, has been shown to exert immunomodulating and restorative effects in vitro and in vivo, working to enhance macrophage phagocytic activity and enhancing lymphocyte response in cases of immunosuppression.⁵⁴ Researchers from the University of Texas-Houston Medical School looked at the effects of astragalus and goldenseal (Hydrastis canadenisis) on pro-inflammatory cytokines produced by cultured macrophages.⁵⁵ Both botanicals were able to modulate the response of stimulated macrophages; astragalus was also about to impact production of TNF-alpha. On its own, goldenseal has the ability to increase IgM production.⁵⁶

From South America comes Uncaria tomentosa, cat’s claw. In vitro work shows cat’s claw can active macrophage phagocytosis,⁵⁷ exert direct antimicrobial activity on certain microbial strains including Streptococcus mutans,⁵⁸ and exert antioxidant and anti-inflammatory effects.⁵⁹ It also appears to exert anti-viral effects, as Brazilian researchers found an alkaloidal fraction of U. tomentosa induced immunomodulation to reduce monocyte infection rates by dengue virus.⁶⁰

Another beneficial botanical is garlic, with a host of studies conducted on the benefits of aged garlic extract (AGE, as Kyolic™, from Wakunaga). Human clinical trials have found AGE can increase the number of NK cells and their activity among patients with inoperable cancers⁶¹ and patients with AIDS.⁶² In vitro work shows AGE can stimulate the proliferation of splenocytes and cytokine release, as well as enhance macrophage activity.⁶³ Chronic administration of AGE may also help improve age-related deterioration of the immune response.⁶⁴

The ocean also yields powerful ingredients for immune support. A review out of Bundelkhand University, Jhansi, India, examined the biological effects of spirulina, a cyanobacterium.⁶⁵ The researchers noted different spirulina preparations influence the immune system by increasing macrophage phagocytic activity, stimulating cytokine and antibody production, and activating T, B and NK cells. Spirulina also exerts antioxidant and direct antiviral effects, they added.

Recent years have seen clinical trials support these initial findings. A study conducted by CJ CheilJedang Corp., Seoul, examined the impact of spirulina-healthy elderly subjects (n=78) who randomly received 8 g/d of spirulina or a placebo for 16 weeks.⁶⁶ Spirulina supplementation significantly increased IL-2 concentrations while reducing IL-6 levels, and also increased plasma antioxidant status. Japanese researchers similarly examined the impact of spirulina on immune function and found adults taking spirulina had increases in NK cell activity and greater IL-12 production.⁶⁷

Spirulina’s ability to modulate immune function was also illustrated in a study out of the University of California, Davis, in which researchers provided a placebo, or 1,000 mg/d or 2,000 mg/d of spirulina (from Earthrise Nutritionals) to patients with allergic rhinitis.⁶⁸ During the 12-week trial period, researchers assessed cytokine production (IL-4, IFN-gamma and IL-2). While intervention was ineffective at modulating the Th1 cytokines, it did result in significantly lower IL-4 levels.

Spirulina is not the only green food investigated for its immune health properties. A specialty blend of edible plant extracts including barley leaves, wheat grass, chlorella and kelp (as Kyo-green, from Wakunaga) was evaluated for its immune-modulating effects.⁶⁹ In vitro assays determined Kyo-green enhanced macrophage activity, to a greater degree than the individual components tested alone, suggesting synergistic properties. Additionally, the combination inhibited in vitro mutation and DNA binding activity.

A specialty extract of the seaweed Fucus vesiculosus (as Maritech® Extract, from Marinova) contains a complex of natural polysaccharides and polyphenols, and may have immune stimulating properties. In an unpublished study conducted by NatMed Research, Southern Cross University, Australia, healthy subjects consumed 100 mg/d of the extract for 28 days, while changes in cytokine levels were examined. Intervention caused a short-term spike in levels of T cells, cytotoxic T cells and NK cells, as well as increased activity among monocytes and granulocytes in the blood. Further, the extract significantly reduced levels of the inflammatory factors IL-6 and IL-10.

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