Black teas are well known in the U.S. for their robust flavors and energy-boosting caffeine effects but, what most consumers don’t know, is that black teas are quite beneficial for maintaining cardiovascular health. Black teas originate from the leaves of a plant called camellia sinensis and are the product of an enzyme-driven oxidation process that ends in the leaves being dried before becoming the robust teas we know and love.
Black tea contains molecules called polyphenols, that act as antioxidants scavenging free oxygen radicals (naturally produced or introduced to the body) to keep your immune system in check and reduce free radical cellular damage. Over the past few years, more studies have added up to provide sufficient evidence to the claims that black tea can improve cardiovascular health by reducing the effects that free radicals have on our bodies.
Back in 2010, a group of researchers from the Netherlands assessed 37,514 healthy males and females over the course of 13 years starting from 1993 and found that the risk of mortality from coronary heart disease was decreased by daily consumption of 3–6 cups of black tea .
In 2013, researchers in the U.K. had shown black tea, in particular, to help lower risk factors for cardiovascular disease (CVD) including low-density lipoprotein (LDL) cholesterol, and systolic/diastolic blood pressures. Having high levels of LDL cholesterol is particularly dangerous for those with a high risk for cardiovascular disease .
Why you may ask? Well, when LDL cholesterol and free oxygen radicals interact in the bloodstream, the LDL cholesterol molecules become oxidized and migrate into the lining of the arteries causing inflammation and recruitment of the immune system cells . The results are not pretty and can lead to plaque build up in the arteries leading to various health conditions such as coronary heart disease (heart attack), peripheral vascular disease, and cerebrovascular disease (stroke).
A meta-analysis conducted by researchers from Zhejiang University in 2015, looked at 411 participants in 10 different studies and concluded that, while black tea consumption had no remarkable effects on total or high-density lipoproteins (HDL), there was a significant decrease in LDL cholesterol, especially in subjects with initial higher cardiovascular risks .
The positive effects of polyphenols found in black tea span beyond LDL cholesterol, as researchers in Japan showed in a study published in 2011 looking at diet-induced obesity in mice fed a high-fat diet. Results showed that black tea polyphenols were also able to inhibit intestinal fat absorption, thus reducing weight gain . Such indications are interesting to note, as obesity increases the risk of developing a number of heart problems.
When it comes to black tea, one of the main concerns often raised is in relation to the caffeine levels in black tea and how this could negatively affect those with high blood pressure. High blood pressure is one of the most important risk factors for cardiovascular disease as approximately 54% of strokes and 47% of coronary heart diseases are attributable to high blood pressure worldwide . Nonetheless, studies have been showing that black tea actually helps reduce high blood pressure and with more than one cup! Researchers from Australia showed that 3 cups per day of black tea over 6 months, supplying approximately 429 mg/day of polyphenols, resulted in lower systolic blood pressure and diastolic blood pressure between 2 and 3 mm Hg .
As with most things in life, balance is key, so one thing to keep in mind with black tea is that it has about 2 to 3 times the caffeine content of green tea. At about 40-60 mg of caffeine per serving, 5 cups (1.2 L) of black tea starts to add up. Remember that 300mg/day is the caffeine threshold you want to watch out for, as the side effects of consuming too much caffeine could actually end up doing your heart more harm than good. So be smart, moderate your caffeine levels based on your individual intake, and delight in a delicious black tea, like Blue Mountain Nilgiri, English Breakfast, or Earl of Grey to mix things up!
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