Black Tea, Green Tea, and Matcha for Longevity and Brain Function

Around the world, we drink literally billions of cups of tea every day. What’s so special about the tea bush? Phytonutrients exclusive to the tea plant appear to be so powerful that they can reverse disease even when merely applied to the skin. For example, the topical application of green tea in ointment form on genital warts results in an astounding 100 percent clearance in more than half the patients tested. It’s no wonder that this wonder treatment is now officially incorporated into the Centers for Disease Control STD Treatment Guidelines. If green tea can do that on the outside of your body, what might it be able to do internally?

Even just the purified green tea compound EGCG, purported to be the main active ingredient, can extend the lifespan of C. elegans under stressful conditions, as well as delaying the deaths of rats by 8 to 12 weeks (extending their average lifespan by about 14 percent). There are yet to be long-term randomized controlled trials, but an umbrella review of 96 meta-analyses of observational studies found that increasing tea consumption by three cups (720 ml) a day may decrease the risk of premature death from all causes put together by 24 percent, the equivalent of adding about two years onto your lifespan. This applied to both green tea and black tea, though green tea may have a slight edge.

Middle-aged and older subjects randomized to 12 weeks of drinking two grams of matcha a day experienced a significant improvement in cognitive function compared to placebo. Matcha is powdered green tea, produced by milling whole tea leaves into a fine powder that can be added straight to water. After all, why waste nutrition by tossing a tea bag when you’re done making your tea, when you can drink the leaves instead? Think of it this way: Drinking steeped tea is akin to boiling a pot of collard greens and then throwing away the veggies and just drinking the cooking water. Sure, some of the nutrition leached into the water, but wouldn’t it be better to eat the leaves themselves?

Because you’re actually eating the whole leaf, a cup of matcha (240 ml) can have up to nearly as much caffeine as a shot of espresso, but in the cognition study, the researchers used decaffeinated matcha, so the cognitive boost wasn’t a caffeine effect. If you want to get into a matcha habit, I would suggest matcha sourced from Japan rather than China to minimize lead exposure. Very little lead leaches out of steeped green tea leaves, so the country of origin is more important if you’re actually eating the leaves, like drinking matcha or throwing tea leaves into a smoothie or something.

Although tea consumption is associated with lower odds of cognitive impairment, it does not appear predictive of cognitive decline, the development of dementia in general, or Alzheimer’s disease in particular. What about treating Alzheimer’s, though?

A pilot study of 30 patients with severe Alzheimer’s were given two grams of green tea leaf powder for two months and experienced the tiniest increase in cognitive function. A similar study on elderly people with much less serious cognitive dysfunction found a more impressive improvement after three months. Neither study had a control group, though, so you can’t tell if the before-and-after enhancement would have happened anyway, or whether the placebo effect played a role. Nevertheless, the results were tantalizing enough to spur a randomized, double-blind, placebo-controlled study.

When actually put to the test against placebo, a year of two grams a day of green tea leaf powder sadly resulted in no cognitive improvements in a group of nursing home residents suffering from cognitive dysfunction. Now the study was performed in Japan, and so all the study participants were already drinking green tea every day and continued to do so throughout the trial (including 100 percent in the placebo group). The researchers couldn’t bring themselves to constrain consumption “because of ethical reasons,” but that does change the nature of the study. All we can really conclude is that additional tea consumption failed to benefit cognition.

Habitual tea consumption is associated with better health-related quality of life in older adults, and a meta-analysis of more than a dozen studies found that tea consumption (both green and black) is associated with a significantly lower risk of hip fracture. However, the data regarding tea and cancer prevention are comparatively weak and inconsistent. Therefore, any mortality benefit derives largely from cardiovascular protection. Drinking black tea doesn’t seem to significantly affect cholesterol or blood pressure (at least in the short term), but both green and black tea consumption can significantly improve arterial function within hours of ingestion. But it may only work if you don’t add milk.

In 2007, the world learned that the addition of milk “completely blunted the effects of tea” when it came to improving artery function. In 2018, we learned it was even worse than that. Men and women were randomized to a month of drinking their black tea black, black tea with milk, or just hot water. The straight black tea group experienced a significant improvement in artery function as expected, but the tea with milk group not only did worse than the plain tea group, they had significantly impaired artery function compared to the hot water group. So, the milk didn’t just neutralize the beneficial effects, but drinking tea with milk was worse than drinking no tea at all. Milk also appears to undercut the benefits of berries, chocolate, and coffee.