The internet is inundated with articles on how much water people should drink. Both healthcare professionals and non-healthcare individuals offer a range of opinions without any scientific facts. For the longest time, the dogma has been that all healthy humans should drink lots of water every day.
The popular advice to ‘drink at least 8 glasses of water a day’ originated not from primary research, but from the U.S. Food and Nutrition Board in 1945, which recommended daily water intake of 2.5 liters per day and stated that the majority of this intake “could come from food sources.”
Unfortunately no one has challenged this dogma, until recently.
There is no question that water is necessary for humans. Water is essential for the maintenance of blood pressure, ensuring the circulation of blood cells, need for cellular function and metabolism and playing a vital role in the excretion of toxins and waste products via the kidney. The intake and output of water in the human body is intricately controlled by a hormone called antidiuretic hormone.
This hormone will become activated when the person is thirsty. If the person drinks too much fluids, the hormone will be inhibited so that the excess water is excreted by the kidneys. The hormone also plays a vital role in the activation and inhibition of the thirst center in the brain.
Thus, when a person is thirsty, he or she will automatically drink water. If he or she is not thirsty then one will not drink any more fluids. What this means is that some people may be perfectly fine drinking one or two cups of water a day and others may drink more. It is impossible to drink more water if one is not thirsty.
There are many external and internal factors that determine how much water a person needs. Some people need to drink more and some need to drink less. For example, people who exercise in hot weather may need to drink more water. In addition, women who breastfeed and individuals who develop diarrhea may need to consume more water.
Further, drinking water helps lower the risk of kidney stones and prevents constipation.
Despite this well established physiological process that has been known for half a century the internet is full of all sorts of advice on how much water people should drink- most of the data is junk science without any scientific validity.
Over the past few decades, healthcare workers have also been encouraging people with kidney disease to drink more water in the belief that the excess water will prevent kidney stones, excrete toxins from the body and maintain kidney function. Individuals with kidney disease have often been advised to drink 8 or more cups of water a day. But is this helpful?
The latest study
A recent Canadian study showed that drinking more water did not slow down the decline in patients with stage 3 kidney disease. The participants in the study were followed for nearly 12 months and there was no difference in the kidney function between participants who were coached to drink more water compared to those who were not coached. These results were a major surprise because previous studies had shown that drinking more water was associated with better kidney function and also resulted in fewer kidney stones.
So how much water should an individual with kidney disease drink?
Based on some current data the individual with kidney disease should:
- Drink fluids as long as there are no restrictions on water intake
- Drink water when he or she is thirsty
- Drink water when he or she exercises and feels thirsty
- Use common sense when it comes to drinking water. If one is not thirsty, then do not drink water
Polycystic Kidney Disease
With polycystic kidney disease more water may provide benefits. Early research has shown a positive benefit with more water consumption and pkd. Currently large trials are being conducted to determine water consumptions impact on PKD.
Change lifestyle
People with kidney disease should change their lifestyle in order to protect their kidneys. Just drinking water is not a magic bullet. This means doing the following:
- The individual should limit the amount of salt in the diet
- Ensure proper control of blood pressure
- Ensure proper control of blood sugar
- Eat a healthy diet that is rich in veggies, fruits, nuts, whole wheat and seafood.
- Limit the intake of red meat
- Take medications as prescribed
- Follow up with a kidney specialist and get regular blood work to determine the status of the kidneys.
Healthy Kidney Inc Water Recommendations
Dehydration is very bad for the kidneys and I have seen better results in kidney health when people drink more water. I recommend 60-80 ounces of water per day depending on your body weight. Herbal teas without added sugar can be counted towards water intake. Check with your doctor to make sure you have no fluid restrictions.
References
High Water Intake and Progression of Chronic Kidney Diseases. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4737661/
Can water intake prevent CKD? A brief review of the evidence
https://www.thelancet.com/campaigns/kidney/updates/can-water-intake-prevent-ckd
