Health effects of tea and coffee

Even though prevailing evidence shows water is always the best choice of beverage, a lot of us choose to drink other beverages, and here we look at some of health effects of coffee and tea.

Tea contains less caffeine than coffee and therefore you have a lower risk of becoming addicted to it. Additionally, tea and coffee may help with weight loss, cardiovascular health and increased bone formation.

Is coffee good for us?

Coffee is the most widely-consumed stimulant in the world. Coffee was, and largely still is, viewed as a tonic with revitalizing properties for the sick and the weary. However, it is not a health drink. It is clearly addictive and there are many better sources of phytonutrients.

So what effects is the coffee fix having on our health?

In fact, the effects of coffee are mixed, probably because it is a complex mixture of different compounds from the bean as well as generated or excluded in the processes of fermentation, roasting and preparation.

Some of these may be beneficial for human health, like vitamins, antioxidants and minerals. Others, like acrylamide and diterpene are noxious chemicals.

Coffee beans grown using sustainable organic practices and in the absence of synthetic pesticides, herbicides and fertilizers also have number of positive effects.

The most well known component is caffeine, the main stimulant in coffee. It acts by blocking receptors in the brain whose job it is to dull brain activity. So by preventing dulling, it stimulates. This may seem useful on Monday mornings or when we’d rather be in bed. But it also increases our blood pressure and metabolism, stiffens our arteries and makes us go to the toilet more.

If we drink caffeine regularly, even as little as a cup a day, we can suffer withdrawal symptoms if we stop. The more coffee we drink, the more likely we will experience the need for a cup! Some of the feeling we get from our morning ‘fix’ of coffee is relief of this withdrawal.

How does coffee impact our health?

Overall, a regular, moderate intake of coffee (2-3 cups a day) does not appear to be harmful to our health.

A regular coffee may slightly reduce the risk of heart disease, diabetes, Parkinson’s disease, Alzheimer’s disease, hip fracture and liver disease. For heart disease and diabetes, at least, this is not the caffeine, as the same benefits are also seen in those who drink decaffeinated coffee, especially when prepared in the absence of chemical solvents (e.g. the Swiss Water method).

It could be that there is something about coffee drinkers that protects them (e.g. they have less stress in the mornings or the social ritual, for example).

Health benefits of tea

Tea is second only to water in its global consumption. About half of the adult population drinks 2-3 cups a day. In western countries, the most widely drunk tea is black tea, prepared from fermented and oxidized leaves.

By contrast, oolong tea is only partially oxidized, while green tea is minimally processed before drying. This creates a range of different flavors, astringencies and caffeine content, which is generally greater the less processing.

You then steep the tea leaves in hot or boiling water to release the complex mixture of chemicals they contain.

The health properties of tea are readily confused with the stimulant effects of its caffeine content. Black teas contain about half the caffeine of most coffees, while many green teas contain more caffeine than coffee.

Contained within the tea leaf are also a number of biologically active compounds such as flavonoids, antioxidants, catechins or tannins, vitamins and minerals. Some of these, but not all, are lost or transformed during prolonged drying and oxidization when making the tea leaves black.

Adding milk to black tea may also reduce the availability of antioxidants.

Some health benefits have been described in adults drinking 2-3 cups of tea a day. For example, a regular cup of tea is associated with a small reduction in the risk of heart attack and stroke. This may be because in many people who aren’t eating fresh fruit and vegetables on a regular basis, their tea can be a major source of dietary antioxidants.

Green tea and disease prevention

Because they are less oxidized, green teas have a greater antioxidant potential, and potentially greater benefits for human health. This is why many people think they have even more benefits for human health than standard black tea.

Studies have have shown having regularly consuming green tea and reduce the rates of some cancers, heart disease and cognitive decline with advancing age.

It’s important not to brew green tea with boiling water, as this can damage some of its antioxidants, as well as increase the release of caffeine and other bitter tasting compounds.

Not everyone likes the taste or has time to drink three cups a day, so you can take extracts in pill form that contain 80% total polyphenols and 55% epigallocatechin gallate.

Last reviewed 15/May/2017

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Dr Merlin Thomas

Professor Merlin Thomas is Professor of Medicine at Melbourne’s Monash University, based in the Department of Diabetes. He is both a physician and a scientist. Merlin has a broader interest in all aspects of preventive medicine and ageing. He has published over 270 articles in many of the worlds’ leading medical journals

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