Fancy a cuppa? UP study finds tea to be as antioxidant-rich as fruit and veg

University of Pretoria (UP) researchers have found that the antioxidant content of certain types of tea can be likened to that found in recommended portions of fruit and vegetables.

For the study, which was published in Toxicology, Professor Zeno Apostolides of UP’s Department of Biochemistry, Genetics and Microbiology in the Faculty of Natural and Agricultural Sciences measured the amount of antioxidants in fruit, vegetables and tea against the amount found in a standard 200mg vitamin C tablet.

The result: an equivalent amount ­– and a compelling reason to incorporate tea into your diet.

“This does not mean that you can ditch your healthy eating habits,” Prof Apostolides cautions. “While tea made from the Camellia sinensis plant has considerable health benefits, tea should not be used as a substitute for fruit and vegetables under any circumstances, and should simply be used to supplement your diet.”

Prof Apostolides’ research was conducted on 15 types of non-herbal tea and 10 types of herbal tea found in supermarkets, as well as a variety of fruit and vegetables. The findings showed that just half a cup of black tea, oolong tea or green tea contained the same amount of antioxidants with radical scavenging capabilities (RSC) as that of a 200mg vitamin C tablet. RSC refers to a substance’s ability to neutralise harmful free radicals – unstable molecules that can cause cell damage. Antioxidants are compounds that counteract free radicals, preventing and slowing down the cell damage and cell death caused by them.

Furthermore, one cup of black, oolong or green tea contains the same amount of RSC as four servings of fruit or 12 servings of vegetables.

Different foods contain different types of antioxidants, and a variety of antioxidants is needed to combat the negative effects of free radicals.

“Free radicals are highly reactive, unstable molecules that are produced as a by-product of the body’s natural metabolism processes,” Prof Apostolides explains. “They only live for a fraction of a second, but during their short lifespan, they can damage the DNA inside your body’s cells.”

The damage that they cause can increase the risk of developing cancer and heart disease, among other health conditions. Free radicals are produced after the body has been exposed to harmful compounds in the environment, such as tobacco smoke, toxic chemicals or air pollution, or prolonged exposure to sun and ultraviolet light. A nutrient-poor diet can also produce free radicals.

“Free radicals can be either harmful or helpful, but a build-up of harmful free radicals (known as oxidative stress) can cause significant damage to the body’s cells,” Prof Apostolides says.

Oxidative stress causes damage to cell membranes, proteins, lipids and DNA. This damage negatively affects how the body’s cells work and how they replicate. A negative effect on cell replication can cause mutations in DNA, thereby increasing the risk of developing cancer.

“The results of the study also showed that tea made from the Camellia sinensis plant contained a significantly larger amount of RSC than the amount found in herbal teas,” Prof Apostolides says. “Rooibos tea, however, is still a close second, with one and a half cups containing as much RSC as that of a standard vitamin C tablet.”

Researchers

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  Professor Zeno Apostolides

  Professor Zeno Apostolides completed his undergraduate studies at the University of Pretoria (UP), and part of his PhD at the University of Delaware in the US, where he developed and evaluated computer simulations for teaching biochemistry, similar to the popular flight simulators used for pilots.

  He joined UP as a lecturer in 1980 and has been doing research at the University for 44 years. For Prof Apostolides, UP offers a broad range of disciplines with which to collaborate, such as chemistry, veterinary, human medicine and computer science.

  “My work aims to support or refute ethnobotanical claims of medicinal plants,” Prof Apostolides says. “We search for medicinal plants that may be used as teas, herbs or spices and that have ethnobotanical claims for treating type 2 diabetes. Many countries have pharmacopoeias that list medicinal plants, especially Britain, Germany, Russia, India, China and the US. The first African herbal pharmacopeia was published in 2010.”

  Type 2 diabetes affects about 10% of the global population. It has a higher prevalence in low-income countries where people consume high-starch diets that are rich in cereals such as rice or maize. 

  “We analyse the constituents of medicinal plants with computer simulations and laboratory experiments to investigate how effective they are in inhibiting amylase and glucosidase, which are starch-digesting enzymes.”

  According to Prof Apostolides, there are good inhibitors in green and black tea, basil and cinnamon. These plants are easily available in most countries at low prices. His team is developing derivatives of the active compounds in these plants, which may be stronger inhibitors of starch-digesting enzymes, and patentable.

  “So for a little higher price, we may be able to provide much stronger inhibitors of the above enzymes. This will better the world we live in, especially for low-income countries. I am the leader in this discipline. I am leading this research in collaboration with UP’s Faculty of Health Sciences.”

  Finding good correlations between computer simulations and laboratory work is a highlight for Prof Apostolides.  

  “Over the past two years, we’ve started using more advanced computer simulations, called molecular dynamics. These programs are available at the Centre of High-Performance Computing, which is supported by the national Department of Science and Innovation.”

  Prof Apostolides adds that he’s been inspired by Prof Yukihiko Hara of Japan, who wrote a book on the health benefits of green tea and conducted several clinical trials with tea extracts.

  “Prof Hara and I are working together to improve the health benefits of black tea,” Prof Apostolides says.

  He hopes to develop a new derivative of a lead compound from green tea that will be a strong inhibitor of starch-digesting enzymes.

  Prof Apostolides says his research matters because it integrates fieldwork on tea farms to improve the yield and quality of tea with the fundamental discipline of biochemistry to understand medicinal plants and their effects on human physiology.

  “With computer simulations, we can dive deep into the structure of molecules and understand them on the level of individual atoms,” he says.

  Prof Apostolides encourages students who are interested in developing new medicines, for animal or human diseases, to consider a degree in biochemistry. People with these skills, he emphasises, are highly sought after by pharmaceutical companies worldwide.

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