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How to make our immune system function at peak level with plant-derived compounds


If we are to live longer, healthier lives, we need our immune system to function at peak capacity.

Boosting the Aging Immune System

  1. Older age is associated with a decline in immune system function, known as immune senescence.
  2. Immune senescence increases the risk for infections, cancer, autoimmune disease, and chronic inflammatory conditions.
  3. Certain plants and fungi have been found to bolster immune system cells and functions, improving immunity.
  4. Reishi mushrooms, Cistanche, and Pu-erh tea have all been shown to improve immune function by various complementary mechanisms.
  5. Intake of extracts of these plants and fungi may help restore immune function, reducing the risk for infection, cancer, and other conditions for which the elderly are at increased risk.

The following plant-derived compounds have shown an ability to help rescue the immune system from senescent decline:

  • Cistanche
  • Reishi mushrooms
  • Pu-erh tea

Together, these natural extracts help combat immune senescence by several complementary mechanisms that include enhancing the activity of natural killer cells and T cells and turning down overactive immune reactions.

This post describes research supporting the use of low-cost plant extracts to help support immune health.

Reishi Mushroom Extract

The immune-boosting properties of Reishi mushrooms have been appreciated in Eastern medicine for thousands of years. Modern science is now validating their health-promoting properties. Studies show that consuming these mushrooms improves immune function and has anti-tumor effects.

In mice, Reishi has been found to promote the maturation and activation of immune system cells such as T cells, natural killer cells, dendritic cells, and macrophages.
Lab studies show that Reishi also helps raise protective IL-10 levels and lower pro-inflammatory IL-6 levels. This indicates that Reishi augments the function of both the innate and adaptive immune systems.

The innate immune system can be thought of as the body’s first line of defense, responding rapidly to potentially harmful insults such as viruses, bacteria, and cancer cells.
Natural killer cells are an important component of this innate immunity. The diminished activity of natural killer cells that occurs with aging predisposes the elderly to high rates of infection by viruses ranging from influenza to various herpes viruses.

The adaptive immune system responds more slowly than the innate immune system but mounts a more specific, powerful attack against pathogens using specialized immune system cells called T cells.

With its ability to boost components of both innate and adaptive immunity, Reishi can protect the aging body from infections. This benefit has been borne out in laboratory studies demonstrating activity against many common viruses, including:

  • Herpes simplex viruses—which cause oral and genital herpes
  • Influenza viruses—which cause the flu
  • Epstein-Barr virus—which causes mononucleosis but can also contribute to the formation of cancer
  • Hepatitis B virus—a common cause of liver disease that can lead to liver failure
  • Human immunodeficiency virus (HIV) — the virus which causes AIDS.
Image Source: Imago Images

Anti-Cancer Properties

In addition to supporting protection from infection, Reishi exhibits anti-cancer properties as well—largely because of its ability to enhance immune function. In particular, the boost Reishi gives to natural killer cells, T cell, and macrophage function aids in the identification and destruction of abnormal cells that may develop into cancer.

Reishi may also directly combat tumors through an array of mechanisms it has demonstrated in the lab: impairing the ability of tumor cells to grow, preventing tumor blood vessels from developing, starving the abnormal cells, and even directly killing cancer

In one study, Reishi mushrooms were applied to various human cancer cell lines. Not only did the Reishi reduce the growth of the cells, but it induced cell death in many of the diseased cells.

Lifespan Extension

Perhaps most impressively, Reishi has been shown to significantly extend the lifespan of mice.30 Researchers followed two groups of mice, one fed a normal control diet, and the other fed a diet enriched with a Reishi extract.

The Reishi supplemented group lived as much as 148 days longer than the control group. Given that the lifespan of a mouse is typically less than two years, this represents a dramatic increase in longevity.

Cistanche Extract

Cistanche is a type of desert plant that, like Reishi mushrooms, has long been appreciated for its medicinal uses in Eastern medicine. Several studies have confirmed the ability of
Cistanche extract to boost immune cells in the body.

In one study, researchers utilized a strain of senescence-accelerated mice. These mice age more rapidly than normal mice and display the same deterioration in immune function seen in human immune senescence.

The mice fed a diet supplemented with Cistanche extract for four weeks had a significantly increased number of T cells and natural killer cells in the blood, and lower pro-inflammatory interleukin-6 (IL-6) levels. This enhancement in immune function translated to an extended lifespan as well. The average age after supplementation with Cistanche was 15% longer than the controls’. In addition to T cells and natural killer cells, Cistanche also helps activate other important immune cells, including macrophages, dendritic cells, and B

Encouraging results have been demonstrated in a human study as well. When elderly subjects took 100 mg of Cistanche extract daily for 12 weeks, there was a 6.1% increase in helper T cells and an almost 12% increase in natural killer cell activity. This increase represents an immune-boosting effect.

Patients also experienced improved markers of vascular function and a decrease in fatigue. No significant adverse effects were observed. Given that these same improvements in immune function resulted in enhanced longevity in animal studies, it can be hoped that the rejuvenating effect Cistanche has on the human immune system may assist in prolonging lifespan in people as well.

A hallmark marker of longevity potential is blood levels of interleukin-6 (IL-6). Older individuals with higher levels of IL-6 tend to not live as long and tend to have a higher burden of chronic disease. On the other hand, older people with lower IL-6 levels tend to be healthier and have better prospects for even longer lives.

This makes sense because elevated IL-6 generates chronic inflammatory signals that result in tissue damage throughout the body.

Image Source: Imago Images

Pu-erh Tea Extract’s Immune Effects

A fermented black tea called Pu-erh has shown benefits for the aging immune system.50
Studies show that Pu-erh tea and its extract combat immune senescence by multiple mechanisms. Two of the chief ones include increasing natural killer and T cells.

In addition to its ability to bolster the immune system itself, Pu-erh tea appears to provide direct antibacterial and antiviral effects as well. Several studies have demonstrated that Pu-erh tea directly kills or inhibits the growth of bacteria and suppresses the growth of
viruses such as hepatitis B.

In one investigation, scientists studied the effects of Pu-erh tea on the senescence-accelerated strain of mice discussed previously. Before supplementation with Pu-erh tea, the mice demonstrated the same features of immune system deterioration seen in aging humans, including lower numbers of active T cells and natural killer cells.

In addition, levels of the powerful pro-inflammatory cytokine IL-6 were markedly elevated in the senescence-accelerated mice, compared with controls. Feeding these mice with Pu-erh tea reversed these markers of immune senescence.

The treated mice experienced enhanced numbers of T cells and natural killer cells and a significant 43% decrease in IL-6—benefits that more closely resemble a normal, healthy immune system. Based on these immune-boosting results, the researchers concluded that intake of Pu-erh tea may help older individuals prevent infection and cancer.

Anti-Inflammatory Effects in Humans

A human study of Pu-erh tea extract further demonstrated its role in reversing inflammatory cytokine levels. The study was performed among a group of patients
with metabolic syndrome, a common condition defined by central obesity, borderline or high fasting glucose, high blood pressure, and elevated blood lipids.

Those with metabolic syndrome have higher levels of inflammation and are at an increased risk of having immune impairments. Subjects were given either Pu-erh tea extract twice
daily or a placebo. They were instructed to exercise and observe a healthy diet during the study period but were permitted no medicines that might otherwise affect the results. After three months, patients provided blood samples for analysis of inflammatory cytokines and other markers of inflammation.

As expected, placebo recipients showed no significant changes in blood levels of TNF-a or IL-6 (proinflammatory cytokines), IL-10 (an anti-inflammatory cytokine), or C-reactive protein (CRP, a marker of total body inflammation).

Subjects supplemented with Pu-erh tea extract showed improvements in immune status as follows:
• 21% reduction in IL-6,
• 23% reduction in TNF-a, and
• 26% reduction in CRP.

These reductions indicate significant decreases in overall pro-inflammatory status. This study also found a 34% increase of inflammation-quelling IL-10, which further demonstrates the overall reduction in inflammation possible with Pu-erh tea extract.
Pu-erh tea extract offers multiple pathways to potentially prevent progress of immune senescence.

Image Source: Imago Images


Immune senescence occurs as people age and puts the elderly at increased risk for infections, cancers, and a variety of chronic inflammatory diseases. Compounds naturally found in certain plants and fungi bolster weakened immune systems.

Reishi mushrooms, Cistanche, and Pu-erh tea can improve immune function by several complementary mechanisms, including amplifying the activity of natural killer cells, T cells, and various other immune system components. They also help suppress the overactivity of immune cells that can result in damaging inflammatory reactions. Adding these nutrients to a healthy diet can help induce improvements in immune cell markers in older age.


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