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Life Extension Magazine December 2013
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Enhanced Winter Wellness Against Colds & Flu

By Michael Downey

Boosting Vaccine Effectiveness!

To establish this effect in people, researchers designed a randomized, placebo-controlled study in which both of these amino acids were tested in healthy elderly humans. For the study, 65 nursing home residents aged 65 or over were randomly divided into two groups. The test group received 280 milligrams of L-theanine and 700 milligrams of L-cystine once a day for 14 days. The other group received a placebo for the same amount of time.19

On day 15, all participants were given a flu vaccine containing three influenza strains.

The scientists found that certain subsets of the L-theanine and L-cystine group had an increased rate of seroconversion, the precise point at which the immune system develops antibody protection against a microorganism as a result of immunization. Notably, the increased seroconversion rate occurred among subjects with low serum total protein or hemoglobin, potential indicators of compromised health.19

The report concluded that, “Co-administration of L-cystine and L-theanine before vaccination may enhance the immune response to influenza vaccine in elderly subjects with low serum total protein or hemoglobin.”

In another human study, this same combination has been shown to reduce the incidence of the common cold by 58%.5

The Aging Immune System
The Aging Immune System

A compromised immune system can present an opportunity for a simple bout of the flu to quickly progress to full-blown pneumonia, which is the eighth leading cause of death for Americans.2

Nutritional deficiencies among the elderly can lower immune defenses.28 For instance, deficiency of iron, vitamin B12, or folate is a common cause of the increased incidence of anemia in the elderly, and this in turn is associated with a greater risk of infectious diseases.5 In fact, malnutrition at any age causes a decline in immune function and increased susceptibility to infection.5,28-30

Further compounding the problem, millions of doctors erroneously prescribe antibiotics to patients seeking relief for symptoms of viral infections. Persistent misuse of antibiotics leads to potentially serious treatment complications, greater risk of death, and may contribute to the development of antibiotic-resistant pathogens.31

As numerous strains of influenza viruses continue to evolve and pose a deadly danger of complications to aging individuals, scientists recognized the urgent need to find a safe and effective way to reverse the reduced effectiveness of flu vaccines caused by age-related immune decline.

If taken together for two weeks prior to vaccination, the amino acids L-theanine and L-cystine enhance efficacy of the flu vaccine in certain groups of elderly subjects.19 This delivers stronger protection against both the flu virus—and its deadly complications.

Reduce the Risk of Common Cold

If co-administration of these two amino acids could boost the effectiveness of the flu vaccine, scientists reasoned that it might also help lower the incidence of the common cold.

The common cold is the most prevalent human illness.5 The majority of cases are acute viral infections of the upper respiratory tract. Conventional treatments such as analgesic agents and antihistamines only help alleviate some of the symptoms, such as sneezing and runny nose.5

Because common colds can lead to serious complications in elderly and immune-compromised individuals,21 scientists set out to determine if L-theanine and L-cystine, could also reduce the incidence of the common cold.

For the placebo-controlled study, 176 healthy men were asked to take a total of 700 milligrams of L-cystine and 280 milligrams L-theanine per day, in two divided doses.5

Over a five-week period, the L-theanine and L-cystine group developed 58% fewer colds than the placebo group.5 Among those experiencing colds, the symptoms of fever and chills were significantly reduced in the theanine/cystine supplemented group.5

The study team reported that, together, L-theanine and L-cystine represent an effective and safe natural ingredient to suppress the common cold—producing no more side effects than placebo.5

Priming the Immune System
Priming the Immune System

In order for any vaccine to effectively do its job, it needs to work hand-in-hand with a healthy immune system. Studies have shown that the older you are, the less effective the flu vaccine becomes. This is a direct result of an age-related decline in immune response.

The amino acids L-theanine and L-cystine are known for their ability to boost factors of the immune system that are diminished with age: glutathione and interleukin-2.19,32,33

Glutathione is the major antioxidant that neutralizes free radicals and reactive oxygen compounds and is essential for the immune system to exert its full potential.19

Interleukin-2 is a cytokine that is important for antibody production and for the differentiation, long-term growth, and proper functioning of T cells.18,34

L-theanine, an amino acid and phytochemical found mainly in tea leaves (Camellia sinensis), is an immune booster.35,36 Theanine is known to stimulate glutathione.19 Theanine and glutathione have been shown to promote a certain subset of white blood cells known as gamma delta T lymphocytes that play a vital role in the production of interleukin-2.18,36 Evidence indicates that a greater intake of L-theanine helps to prime gamma delta T cells, activating them to a state of readiness.36,37

L-theanine also enhances the immune system by stimulating the release of immune system proteins called cytokines.19,36

L-theanine also contributes to the absorption of another amino acid important to the immune responsiveness: L-cystine.19 The amino acid L-cystine is a precursor to the antioxidant glutathione. L-cystine is converted to glutathione, which stimulates gamma delta T-cells to release the immune factor interleukin-2.19