You will probably recognize that one of the more recent trends in the world of foods and beverages is understanding what is healthy for the body. A quick search online reveals that there is much to know, not only about the body but also about the impact various substances have on it. The idea behind green tea is that it's healthy, and for some, this healthy component brings up important distinctions such as "catechins".
This article will review another area of green tea and our bodies, namely whether green tea is healthy or unhealthy for your kidney(s).
What do you know about your kidney(s)?
You have two kidneys, and they are approximately bean-shaped organs. The size of a fist that is situated below your rib cage on each side of your spine. Each kidney is made up of roughly a million units called nephrons. Each of your nephrons has a filter called the glomerulus and a tubule. The glomerulus filters your blood, and the tubule returns what is necessary to your blood. Blood flows to your kidneys via the renal artery, which is a large blood vessel that splits until your blood reaches the nephrons. Your kidneys filter approximately 150 quarts of blood a day; most of it is returned to your body.
In fact, your kidneys have higher blood flow than your brain and liver. It is a unique organ given that most of us start out with two yet only require one-half of a kidney to filter our body’s blood. In an odd relationship with your liver, your kidneys may also produce vitamin D if the liver cannot. Another important component of our kidneys is that they make hormones that directly help control blood pressure, create red blood cells, and keep your bones healthy.
Healthy kidneys are important. Due to the functions kidneys perform and the harmful substances that may move through them, they are susceptible to a number of issues, including kidney failure, kidney stones, uremia, and chronic kidney disease, among many others.
Green tea and your kidneys
Of course, drinking green tea affects your kidneys, but how?
We talked briefly about catechins and their impact viz-a-viz the liver. Let us spend a few more minutes on the most common catechin found in green teas and its support in preventing Chronic Kidney disease: Epigallocatechin-3-gallate, or EGCG. When discussing chronic kidney disease, we have a form of kidney disease that slowly yet progressively leads to a loss in renal function. One of the more common causes of chronic kidney disease is, yes, diabetes (As a quick note, green tea may actually help lower the risk of type-2 diabetes). However, it may also include hypertension, obstruction, and other issues. Kidneys can be exposed to harm like any other organ in the body. In fact, the kidneys of many people are at high risk of oxidative stress.
Oxidative stress can lead directly to chronic kidney disease and its progression. None of this sounds good, but EGCG has been shown to support your kidneys and help stave off renal decline. Further, The American Journal of Clinical Nutrition has also shown that green tea may actually help regulate blood sugar, which is not only good for staving off chronic kidney disease but also assists diabetics in their own struggles with blood sugar levels.
According to the Chinese Medicine Journal, a 2010 literature review noted that green tea consumption has been linked to the prevention of cancer in the kidneys (among many other parts and organs of the body). This is largely due to the sheer number of polyphenols, which are antioxidants. In this review, the authors also highlight that green tea has been linked to lower blood pressure, which directly benefits the overall functionality of our kidneys. Conversely, the Heart and Stroke Foundation states that over a given amount of time, relatively high blood pressure can cause the arteries around the kidneys to narrow, weaken, or harden. This may lead to an inadequate amount of blood being sent to the kidneys.
Of course, there are concerns related to kidney stones and green tea. A recent study in the journal Nutrients concluded that green tea consumption does not lead to kidney stones. Chinese researchers, in reply, have found that green tea extract, for example, changes the shape of calcium oxalate and makes it less likely to band together, making it easier to move through the kidneys. In fact, studies have shown that there is no link between the substance in green tea and damage to one’s kidneys.
Do I need to worry about its impact on my kidneys?
Green tea can, in fact, damage your kidneys. Like green tea and its impact on your liver, for example, too much green tea or green tea extract can be toxic. The harmful effects of green tea are often due to three major factors: Its caffeine content, the presence of aluminum, and, according to Chinese Medicine’s review, "the effects of tea polyphenols on iron bioavailability." Green tea should be avoided if your doctor states so or if you’re suffering from heart conditions or major cardiovascular problems. It is recommended that pregnant and breastfeeding women limit their green intake to two cups a day.
For those suffering from renal failure, high levels of aluminum can lead to neurological disease. For the more popular, up to 10 small cups of green tea a day is likely fine, according to Chemical Biology and Pharmacognosy Professor Chung Yan. At the end of the day, chances are most of us tea lovers do not need to worry, but it is important to know what impact green tea does have on the body!
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Hi Mike,
Thank you for the comment and it’s a good question after reading our blog post. First, bioavailability means a medicine, drug or other substance’s ability to be absorbed by the body.
About iron bioavailability as one of the three major factors of harmful effects, this is in short, iron deficiency or lack of iron absorption because green tea contains tannins that prevent your body from absorbing iron. When you are iron deficient, the doctor will probably say to avoid drinking tea just before, during, and just after your meal since tannins will block iron from your meals.
About the presence of aluminum, it means there is aluminum in the green tea plant (Camellia Sinensis), and too much drinking of green tea will lead to many aluminum in the body that can lead to Alzheimer’s or any neurological disease.
After reading the article I am more confused… it’s good! …but not really! …it’s good! …but not really… “presence of aluminum”, suggests reduced “iron bioavailability” …there is no firm conclusion. I don’t like that.