Health Professional Newsletter Welcome to the sixth newsletter from theUnited Kingdom Tea Council. This service will keep you up to date with currentTea4Healthactivities and events and inform you of the latest published research. We'll keep you updated on a quarterly basis withnewsand views from across the tea industry. Research Update The best way to get flavonoids from tea –let it brewAccording to results from a new study, longer brewed te a has higher concentrations of flavonoids and antioxidant activity than tea that is only briefly brewed. These findings are unaffected by the addition ofmilk. Flavonoids have recently received much attention in relation to their antioxidant activity. However there has been much debate as to whether these antioxidant properties are sustained once inside the body, as well as the effect of milk on this action. While some studies have suggested that adding milk can affect the bioavailability and antioxidant potential of flavonoids, others have found no such effect. It has been suggested that the reason for these differences is that brewing time do es not get taken into account in these studies. The purpose of this investigation was to examine the ef fect of brewing time on flavonoid concentration as well as their antioxidant potential. The effect of adding milk on antioxidant capacity was further investigated in an intervention study with human volunteers. Researchers at the Rowett Research Centre in Aberdeen brewed 3 grams (equivalent to 1 UK tea bag) of tea in 300mls of freshly boiled water. The tea was infused for 3, 5, 7 and 10 minutes. 6 different brands of tea were infused in this way. Each tea infusion was stirred once when the water was added and filtered at the end of the infusion time to remove any tea leaves. The antioxidant capacity was measured using the ferric reducing ability of plasma (FRAP) method. The different brands of tea showed similar patterns in releasing flavonoids f rom tea leaves. Flavonoid content, as well as antioxidant concentrations, increased with infusion time, levelling off after 7 minutes. The 7 minute tea infusion had up to 60% more flavonoids than the tea that had been infused for 3 minutes. The increase in FRAP value (the measurement of antioxidant activity) correlated with the flavonoid content and was not affected by the addition of milk. To examine the effect of tea once it had been drunk, 9 healthy male volunteers were randomly assigned to 3 groups and consumed 3 different beverages on 3 different occasions 1 week apart. After refraining from drinking tea for 24 hours and fasting overnight, volunteers drank 400mls (equivalent to 2 cups) of either black tea with water, black tea with semi-skimmed milk, or a control (water with semi-skimmed milk). The
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L-theanine improves memory, attention, and is synergistic with caffeine.
A double blind, placebo controlled study of LGNC-07, a green tea extract containing L-theanine,
or placebo examined cognitive skills in adults with mild attention deficits disorders in response
to treatment for 16 weeks. Neuropsychological tests and EEG evaluated memory, attention, and
brain activity. LGNC-07 treatment led to improvements in each parameter, concluding that long
term, high dose (1600 mg/day). L-theanine supplementation can enhance cognition in individuals
who find it difficult to focus[4].
Current research shows that combination of L-theanine and caffeine produces a synergistic effect
and mediates cognitive benefits. A study of healthy adults given either L-theanine (100mg), L-
theanine(100 mg) + caffeine(50 mg), or placebo, reported that only the L-theanine combination produces significant results in response time and correct answer frequency during a memory and
L-theanine increases the inhibitory neurotransmitter, glycine
Glycine is an inhibitory neurotransmitter with analogous properties to GABA. Glycine and
GABA receptors are structurally similar and often co-localize in the same subset of cells to
regulate inhibition[11]. An L-theanine supplement can directly elevate glycine concentration in
the brain [12](Fig 6). Furthermore, while glycine mediates glutamate inhibition, it promotes the
release of dopamine within the striatum, a part of the forebrain receiving input from the cortex to
modulate behavior. L-theanine’s mood regulating properties and balance of neurotransmission
are hypothesized to directly result from elevated glycine.
L-theanine enhances immunity through priming T-lymphocytesThe body’s defense against foreign particles is regulated through a number of immune cell types.
A special subset of T-lymphocytes know as gamma-delta T-cells recognize foreign particles
based on a different mechanism than other T-cells. The chemical structure of L-theanine primes
gamma-delta T-cells and enhances their capacity to proliferate and secrete cytokines, helping the
body to decrease the incidence of immune challenges[13].
The anecdotal evidence from centuries of tea drinkers has led to the investigation of its active
constituents. The health benefits and effects on cognition of L-theanine are well studied and
include relaxation, alertness, memory improvements, increased attention, increased immunity,
and long-term neuroprotection. The biological link between L-theanine and these benefits is alsowell characterized. The chemical similarity to GABA permits L-theanine to cross the blood-brain
barrier and mediate inhibitory neurotransmission. This inhibition produces profound cognitive
effects by moderating glutamate excitation, increasing glycine levels, and elevating dopamine
release. Ultimately L-theanine promotes a balancing of excitation in important brain regions. In
addition, L-theanine can stimulate the production of neurotrophic factors, such as BDNF, to
decrease anxiety and elevate mood, and prime a subset of T-lymphocyte immune cells to help
keep the immune system strong.
The only negative results that have been published regarding L-theanine show no net benefit to
supplementation during a particular cognitive task. However, there are a significant number of
studies that conclude the maximal benefit occurs when L-theanine and caffeine are combined.
Caffeine is a known neurostimulator and enhancer of cognition. Although it may be contrary to
the philosophy of Alpha BRAIN, a low dose of caffeine in combination with L-theanine will
provide the maximum cognitive benefits.
Replacing the GABA component with L-theanine should not alter the effectiveness of Alpha
BRAIN. Both mediate inhibition and have proven to reduce anxiety when taken as a supplement.
Furthermore, the L-theanine provides an array of benefits that can outlast the acute effects of
relaxation, such neuroprotection and immune support. Overall, including L-theanine into theAlpha BRAIN formula is well advised.
Dosage and Warnings
The typical dose of L-theanine used in most studies was between 200-250 mg. Toxicity can
occur at dose of 5000 mg.Ingredient Summary
L-theanine is an amino acid isolated from tea leaves and the major contributor to the health
benefits of green tea. Chemically similar to our own inhibitory neurotransmitters, GABA, L-
theanine promotes a healthy balance of excitation and inhibition in our brain. The health benefits
include assisting the body with relaxation, increased attention, decreased stress, immune support,
and long-term neuroprotective effects.
References1. Wakabayashi C, Numakawa T, Ninomiya M, Chiba S, Kunugi H: Behavioral and molecular evidence
for psychotropic effects in L-theanine. Psychopharmacology (Berl).
2. Gomez-Ramirez M, Kelly SP, Montesi JL, Foxe JJ: The effects of L-theanine on alpha-band
oscillatory brain activity during a visuo-spatial attention task. Brain Topogr 2009, 22:44-51.