Green Tea and Black Tea

Around the world, we drink billions of cups of tea every day. Even the isolated green tea component EGCG (epigallocatechin gallate), presumably the most important active component, can extend the lifespan of the roundworm C. elegans under stress conditions and, beyond that, delay death in rats by eight to twelve weeks (and extend their lives by about 14 percent). Even though randomized, controlled long-term clinical trials are still lacking, an umbrella review of 96 meta-analyses of observational studies found that three cups of tea per day can reduce the risk of premature death in terms of all-cause mortality by 24 percent. That corresponds to about two additional years of one’s lifespan. This applies to both green and black tea, though green tea may be a bit more effective. (See details at see.nf/greenblack, where I also discuss some rather disappointing results on the use of matcha tea for the treatment of Alzheimer’s.)

No Milk

It’s assumed that the observed longevity benefit of tea consumption is largely due to cardiovascular protection, because consuming both green and black tea can significantly improve arterial function within hours. But that works only if you leave out the milk. Since 2007, we’ve known that milk “completely negates the effects of tea” when it comes to improving arterial function. Since 2018, we’ve known it’s even worse. Women and men were randomized into groups and asked to drink black tea either plain, with milk, or just hot water for a month. The group that consumed the black tea plain experienced, as expected, a clearly measurable improvement in arterial function. The tea-with-milk group not only did worse than the black-tea group, but suffered a marked impairment of arterial function compared with the hot-water group. So the milk not only neutralized the benefits; drinking tea with milk was worse than not drinking any tea at all. Milk also negates the benefits of berries, chocolate, and coffee.

Red Tea

All black, green, and white teas come from the same evergreen plant (Camellia sinensis), whereas herbal tea is what you make when you pour hot water over any other plant. In the chapter on AMPK, I covered hibiscus tea, and in the chapters on glycation and inflammation, chamomile tea. Rooibos, also known as red tea or redbush tea, is another important herbal tea that may have an anti-aging effect. Presumably because of its antioxidant properties, it was able to extend the lifespan of C. elegans under oxidative stress conditions by up to 23 percent. In a comparative study of 15 herbal teas in which antioxidant activity was measured in vitro, redbush tea came in second place (behind dandelion).

At see.nf/red, I discuss the best way to prepare red tea. Ideally, it should simmer for a while, namely at least five minutes. Black tea should steep for four minutes, green tea for three minutes at 85 degrees Celsius, and white tea for seven minutes at 98 degrees. Surprisingly, tea bags are better than loose tea, because in tea bags the leaves are much finer, so the substances in the tea are released more easily.

Soft Drinks

Now we’ve covered some of the best beverages—but what about the worst?

A regular can of soda contains about nine spoonfuls of sugar. When you consider that sugar-sweetened beverages are the largest source of added sugar in the diet in the United States, it’s not surprising that their consumption is associated with premature death. The sugar content of each additional can daily increases overall mortality by about 8 percent, likely due to the increased risk for heart disease and diabetes with which they are associated.

Carbonated diet drinks are also associated with increased mortality, but at two servings a day the risk is 8 percent higher—only half as much as with regular sodas. People who drink a lot of artificially sweetened sodas are also more likely to be overweight or obese. It’s less that diet sodas create health problems, and more that health problems prompt people to drink diet sodas—so-called reverse causation. Weight was included as a factor in all analyses, and the mortality risk remained significantly elevated. This was also the case when the studies did not include the first few years of follow-up, to exclude those who may have switched to diet drinks to counteract health problems shortly before their death. An article about a Women’s Health Initiative study that had found a connection between diet soft drinks and stroke risk was titled: “Artificial Sweeteners, Real Risks.” In How Not to Die, you’ll find in the section “Not Sweet Nothings” details about how artificial sweeteners can wreak havoc on our microbiome and our metabolism.

Alcohol

When I sat down to research for this section, to my surprise I came across a paper titled “Tequila … increases the lifespan of Drosophila melanogaster”—so, fruit flies. I pictured swarms of tipsily staggering little flies, but unfortunately: no. “Tequila” is just a name that a creative fly geneticist gave to a fruit-fly gene. Tequila (the liquor) doesn’t give fruit flies a longer life, then, but what about us?

As it turns out, alcohol consumption ranks seventh among risk factors for global mortality and leads to the deaths of millions every year. Alcohol costs three times more healthy life-years than all illegal drugs combined. About half of all alcohol-related deaths have immediate causes such as car crashes; the other half play out more slowly, with alcohol-related liver damage in first place. In the United States, alcoholism has risen by about 50 percent in the last 20 years, as have ER admissions due to alcohol and alcohol-related deaths.

There is agreement that binge drinking, drinking during pregnancy, and high alcohol intake are bad, but what about “moderate” alcohol consumption? With regard to aging, in vitro experiments showed that even the amount of alcohol in one to two drinks lowers NAD+ levels and the activity of the protein sirtuin in human brain cells. On the other hand, alcohol is converted in our bodies into acetic acid, which activates AMPK. Unfortunately, though, a toxic intermediate product is produced before the alcohol is fully converted to acetic acid, namely acetaldehyde, and that is a known carcinogen. That could be why alcohol is blamed for the increased risk of various cancers, such as breast and colon cancer—even in people who consume no more than one alcoholic drink a day.

Yes, alcohol may be an addictive, numbing carcinogen that causes birth defects, but what role does it play for the heart? Might it help lower the risk of heart disease, especially since alcohol consumption has been shown to raise HDL, the supposedly good cholesterol? Unfortunately, HDL is no longer thought to have a protective function, since Mendelian randomized studies found that lifelong high HDL levels do not lower heart disease risk (whereas lifelong reduction of the bad LDL cholesterol by the pure chance of having good genes does in fact lower risk).