Drinking Hot Water: Health Benefits and Risks

Benefits and Risks of Drinking Hot Water

The benefits of hot water are based on anecdotal reports, but there is some emerging and tangentially related scientific research in this area. Some people report feeling benefits from hot water drinking, especially first thing in the morning or right before bed.

The diagram below shows some potential benefits of drinking hot water, including the promotion of better digestion, help with weight reduction, positive effects on the functioning of the central nervous system and blood circulation, improved metabolism, and help in protecting the kidneys while diluting waste materials in the blood. It is specifically beneficial for people suffering from heartburn and acid reflux.

Health Benefits of Hot Water

By hot water, we mean between 54° and 71°C (130° and 160°F). Hotter than this can cause tissue damage. Staying hydrated is important regardless of the temperature of the water, but there is sufficient evidence to support the health benefits of drinking hot water to make it a worthwhile low-cost practice at least some of the time.

Drinking plain hot water is an essential part of life for most people in Asian countries, especially China and Japan. Many people in China carry a thermos of hot water wherever they go because they strongly believe drinking hot water is good for health.

Table of Contents

What Are the Benefits of Drinking Hot Water?

These are the benefits of drinking hot water.

  1. Hot water promotes better digestion.
  2. Body detoxification is aided by hot water.
  3. Blood circulation is aided by hot water.
  4. Weight loss is aided by hot water.
  5. Drinking hot water can assist to relieve discomfort.
  6. Hot water is strong against colds.
  7. Stress can be relieved by drinking hot water.
  8. Drinking hot water may help the central nervous system work better.
  9. You can stay hydrated by drinking hot water.

While there is little scientific research into the benefits of hot water to date, there are varying degrees of agreement around these points by health and wellness experts, as well as on the general benefits of water.

1. Hot Water Promotes Better Digestion

A 2003 study found that switching from cold water to hot water promotes digestion. It was entitled Water-Induced Thermogenesis and carried out by Michal Boschmann et al. from the Humboldt University in Germany.

The study followed 14 healthy men and women and found that drinking 500 ml of water before a meal can increase metabolism by 30%. The researchers concluded that the increase occurs within 10 minutes, and lasts for 30-40 minutes after hot water consumption, with the optimum time being the beginning of the day. This chart from the study’s results shows how much more energy the body uses before and after drinking hot water.

Effect of Drinking Water on Metabolism

Drinking hot water helps break down food faster than drinking cold or warm water. Drinking cold water can harden the oil in foods and create a fat deposit in the intestine, unlike when you drink hot water. The opposite happens when you drink hot water. Hot water also dilates blood vessels in the gut which acts as a catalyst and aids digestion. The study goes on to note that hot water aids in regularizing bowel movements, thereby reducing the risk of constipation.

2. Body Detoxification Is Aided by Hot Water

Hot water aids body detoxification by raising body temperature to cause sweating, which then allows the body to expel waste through sweat. Sweat glands help the skin filter toxins out of the body, allowing it to expel blood waste materials at an increased rate and cleanse itself.

Detoxification is a chain of events - the liver cleanses the system by changing the chemical nature of many toxins, and the kidneys filter toxins out of the blood into the urine.

Some toxins can be easily removed but some require additional intervention. The presence of water improves the functions of the liver and kidneys to help dilute toxins in the bloodstream and make it easier to expel the waste material from the body. This diagram shows different parts of the process by which toxins enter, are processed, and are removed by the body.

Process of Detoxification in Body
 

There are no direct studies to verify the broad claim that body detoxification is aided by hot water. However, a 2016 Chinese study undertaken by the Institute of Environmental and Chemical Engineering in Zhenjiang to monitor levels of heavy elements in residents’ blood, noted that people who exercised regularly recorded lower levels of toxin. They also found traces of heavy metals in sweat and urine samples, with a higher concentration in sweat. Presumably, as a result, physically active residents showed about 10% less lead in their blood.

Sweating is a potential method for eliminating toxins in the body according to scientific research. Drinking hot water to the point of inducing sweat may help remove toxins. There are differing opinions on the extent of detoxification, but most experts including Manhattan-based functional medicine physician Jeffrey Morrison agree that sweating aids in removing impurities. "The primary detox organs are the liver and kidneys, but sometimes they’re not able to get rid of certain toxins”. He goes on to explain, “What doesn’t leave gets stored in the fat, so the body gets rid of it through a secondary system, which is sweat".

Drinking hot water can also minimize if not eliminate discomfort caused by acid reflux. Acid reflux occurs when the valve that connects the stomach to the esophagus, or food pipe, is weakened and the stomach acid flows back into the food pipe.

According to a 2008 controlled trial conducted by the Department of Internal Medicine-Propaedeutic at Attikon University General Hospital in Greece, water increased the gastric pH levels after one minute, which was much faster than the time medications took to give relief.

3. Blood Circulation Is Aided by Hot Water

Hot water is a vasodilator. Meaning it expands blood vessels, relaxes the muscles, and positively impacts circulation. Even brief improvements in circulation can support better blood flow to muscles and assist in health maintenance, from cardiovascular function to muscle pain relief. This diagram illustrates how the expansion of blood vessels supports better blood flow.

Blood Vessel Expansion Increasing Blood Flow

There is limited scientific proof to substantiate the claim that the act of drinking hot water will have this effect. However, according to a review of 13 studies undertaken by the Department of Nursing at Kyung-In Women’s University in Korea entitled The Thermal Effects of Water Immersion on Health Outcomes, immersion in warm water appears to improve blood flow in patients.

Applying this same logic to the consumption of hot water is currently the only possible tenuous scientific support to the notion that drinking hot water may improve circulation.

4. Weight Loss Is Aided by Hot Water

Scientific research supports the claim that weight loss is aided by drinking water before meals, but results regarding the temperature of the water are mixed.

According to a study by Michael Boschmann and Jochen Steiniger entitled Water-induced Thermogenesis, drinking 500 ml of water before a meal increased metabolism by 30 percent. This metabolic step-up lasted for 30-40 minutes, following water consumption. The study states that drinking hot water is a “cost-free intervention that can be a useful adjunctive treatment in overweight and obese individuals for attaining an increase in energy expenditure”. Raising water temperature from 22 degrees to 37 degrees Celsius produced a smaller increase in metabolism, however. The following plot from the study shows this effect.

Effect of Water Temperature on Metabolism

In contrast with the previous study, drinking hot water positively impacts blood pressure in ways helpful for weight loss. David Robertson, one of the researchers at Vanderbilt University Medical Center has shown that ordinary water increases the activity of the nervous system, which raises alertness, blood pressure, and energy expenditure.

5. Drinking Hot Water Can Assist to Relieve Discomfort

Drinking hot water can assist in relieving discomfort according to a study done by a trio of Turkish specialists. Nefise Çalışkan, Hülya Bulut, and Ali Konan conducted a randomized trial on 60 patients who had undergone surgery and noted that drinking hot water assisted in relieving gastrointestinal spasms. They went on to conclude that drinking hot water may have favorable effects on intestinal movements and gas expulsion. The results of this study regarding patient comfort and time to return to normal bowel function are plotted below.

Effect of Postoperative Warm Water Intake

6. Hot Water Is Strong against Colds

A 2008 study by A Sanu and R Eccles of the Cardiff School of Biosciences in the UK notes that you can get lasting relief from a runny nose, coughing, sore throat, and tiredness by drinking hot drinks. The specialists monitored 30 subjects with symptoms of cold and flu and found that the hot drink was more effective than the same drink at room temperature. The graphs below show the effects of warm versus room temperature drinks on various cold symptoms, as reported in this study. Hot water transiently increased nasal mucus velocity.

Effects of Drinking Water on Cold Symptoms

7. Stress Can Be Relieved by Drinking Hot Water

Findings from a 2015 study by Suchita Patel et al. entitled Amazing Wonders Of Two Stages Of Water indicate that drinking hot water is a useful tool in managing stress, especially because it helps alleviate stress-induced hypertension or high blood pressure. Hot fluids warm your body, help increase blood flow, and may lower blood pressure.

While no research to date has definitively linked hot water consumption to stress or pain relief, people do use heat packs and hot water bottles to reduce pain. Gerard A Malanga and his team conducted a study in 2014 to look into the efficacy of heat therapy and concluded that it provides short-term reductions in pain and disability for patients with musculoskeletal injury as well as an increase in blood flow, metabolism, and elasticity of connective tissues. Drinking hot water may provide similar internal relief.

Similarly, a 2014 study by researchers at Forenap Pharma in France recommends having a cup or two of hot water as an easy way to get blood flowing and keep stress at bay.

8. Drinking Hot Water May Help the Central Nervous System Work Better

Researchers at the Department of Psychology at Swansea University tried to assess the adverse consequences of dehydration on physical and mental performance, blood pressure, and heart rate and came to a clear conclusion. Task-related activity in the autonomic network of the brain was reduced when subjects were not drinking enough water. Whether this also impacts the central nervous system is not yet established, but for those who prefer drinking hot water, it can be just as effective as cold water at preventing the negative effects seen in the study.

9. You Can Stay Hydrated by Drinking Hot Water

Drinking water at any temperature will help you stay hydrated. People who prefer having a hot drink such as tea or coffee in the morning are getting the hydration benefit of the hot water as well. If they replace the coffee by drinking hot water, they will also reduce the negative effects of caffeine.

Hydration benefits of caffeine versus water

As a renowned physician with McFarland Sports Medicine, Dr. Sarah Bancroft says, “All of the musculoskeletal system needs hydration to make sure it is working properly”.

What Are Some Misunderstandings about Hot Water?

Some misunderstandings about hot water are that the following claimed benefits are proven when in reality they have little or no scientific backing.

  1. Body detoxification is aided by hot water: there is limited scientific backing.
  2. Weight loss is aided by hot water: there is limited scientific backing.
  3. Blood circulation is aided by hot water: there is no direct scientific backing.
  4. Drinking hot water may help the central nervous system work better: there is no scientific backing.

Given the research on the benefits of hot water remains limited, these benefits may yet be proven, but for now, it is a misunderstanding to think they are.

What Are the Risks of Drinking Hot Water?

The risks of drinking hot water include tissue damage, reduced thirst signals that can cause you to not drink as much as you should, and increased sweating that may require more hydration than normal when exercising.

The optimal drinking temperature for hot fluids is 58°C (136 °F) as per a 2008 study conducted by the Department of Mechanical Engineering at The University of Texas. This temperature is optimal for reducing scald burn hazards and improving consumer satisfaction. The study goes on to note that 71°C / 160°F is the maximum for serving hot beverages including hot water. This diagram shows key water temperatures relevant to drinking hot water.

Temperatures for Warm Drinking Water

According to a 2015 study published in the European Journal of Pharmaceutical and Medical Research, drinking hot water can potentially damage the tissue in the mouth and esophagus. This is specifically pertinent if the temperature of hot water is higher than the body temperature.

According to another study by the US Army Research Institute of Environmental Medicine that looked at the effects of water temperature on drinking patterns, drinking hot water makes you less thirsty. This can be detrimental on days you are exercising and losing water through sweat. If you opt to drink hot water, be aware that you may not feel thirsty as often as you should.

A 2013 study published in the International Journal of Clinical and Experimental Medicine found that drinking hot water makes the body sweat more in comparison to drinking room temperature or cold water. The body needs to retain extra hydration during an intense workout, so switch to cooler temperature water when doing strenuous activities.

Can Drinking Hot Water Cause Miscarriage?

Drinking hot water can not cause miscarriage. There has been no scientific research showing this to be the case. There have been several studies with a tangential relationship, including one conducted in 2003 by the Kaiser Foundation Research Institute in Oklahoma that found no connection between hyperthermia (overheating) on a fetus from any external source of heat.

What Is The Ideal Temperature to Drink Water?

The ideal temperature to drink water depends on whether it is for tasting, thirst-quenching, rapid hydration, feeling refreshed, health, weight loss, or enjoying hot drinks.

  • The ideal water temperature for tasting flavors is 20°C / 68°F (room temperature). According to water sommelier Martin Riese, cold water numbs the cells in the mouth and doesn't allow full taste sensations. Water at room temperature provides a balance between cooling refreshment and taste.
  • The ideal water temperature for thirst-quenching is 40°C / 104°F (lukewarm). Research done by the US Army Research Institute of Environmental Medicine found that fluid consumption was reduced by 29% when warm water (40°C) was provided. This indicates that drinking warm water correlates directly with feeling less thirsty.
  • The ideal water temperature for rapid hydration is 16°C / 61°F (slightly chilled). Research on water temperature published on The National Center for Biotechnology Information (NCBI) website in 2013 showed that a water temperature of 16°C is the optimum point for dehydrated athletes or other subjects. This is because slightly chilled water induces higher rates of water consumption and results in lower rates of sweating, increasing the body's ability to hydrate efficiently.
  • The ideal water temperature for feeling refreshed is 6°C / 43°F (cold). A 2016 research paper about oral cooling published by the NCBI explains that when feeling overheated, cold water around 6°C provides a feeling of energizing refreshment.
  • The ideal water temperature for health is your personal preference. The best water temperature is the temperature that encourages a person to stay hydrated. It is a matter of personal preference. Ordinary water is generally considered the best solution for keeping a sick body hydrated.
  • The ideal water temperature for weight loss is your personal preference. When losing weight, there is no evidence that water temperature is relevant. Engage in physical activity, eat well, and enjoy drinking water at the temperature you like. Drinking hot water does aid in weight loss but staying hydrated is more important.
  • The ideal water temperature for hot drinks is 58°C / 136°F (hot but not enough to burn tissue in the mouth). The benefits of drinking hot water include the promotion of better digestion, help with weight reduction, positive effects on the functioning of the central nervous system and blood circulation, and improved metabolism.

What Is the Temperature of Hot Drinking Water?

The temperature of hot drinking water should ideally be 58°C / 136°F and not more than 71°C / 160°F. Water hotter than 71°C can scald the throat and mouth.

Ayurvedic medicine does make a different claim. Ayurveda expert and author Mira Manek says a rule of thumb is to avoid drinking water that is higher than your body temperature. "If you drink water that's about the same temperature as your body, you're not disrupting the body's optimal state or interfering with food absorption."

What Can You Mix with Hot Water to Make It More Beneficial?

You can mix garlic, lemon, and honey with hot water to make it more beneficial, though researchers at the Linus Pauling Institute of Oregon State University report that to date it cannot be shown to have a major impact on treating any disease. The three ingredients together are often referred to as garlic tea, with ginger sometimes added. Each ingredient has specific benefits and a few items to be careful about.

  • Garlic in hot water is rich in antioxidants and can help improve kidney function. The National Institutes of Health says that garlic is safe for most people in typical amounts, but it can increase the risk of bleeding if you take a blood thinner or when undergoing surgery.
  • Lemon in water helps prevent kidney stones because of its citrate content. Researchers have also found benefits for immune system support and against diabetes.
  • Honey has antioxidant and anti-inflammatory properties, along with antimicrobial, anticancer, antidiabetic, antiviral, and antiparasitic impacts. Honey also helps protect the cardiovascular, nervous, respiratory, and gastrointestinal systems. These properties are best at room temperature, though beneficial effects certainly remain when hot, so adding it to hot water is only beneficial.

Ayurvedic medicine makes some claims about the benefits of garlic as a builder of natural immunity against infections. Garlic benefits for the immune system have been backed up by scientific research by researchers at Aachen University in Germany, Instituto de Investigaciones Biomédicas in Mexico, and several other universities in Mexico, Germany, and Canada.

Ayurvedic practitioners claimed in a 2010 report in the Ayurvedic journal AYU that honey heated to 60°C can turn toxic. This claim generated headlines, but the research does not back it up. It assumed a compound known as HMF which increases when honey is heated is toxic.

HMF is common in foods including baked goods, coffee, and fruit products. A 2011 study by the German Federal Institute for Risk Assessment found “no relevance for humans concerning carcinogenic and genotoxic effects can be derived” in relation to HMF. HMF also has positive health aspects, with a 2005 study from the Children’s Hospital of Philadelphia showing potential in therapy for sickle cell disease.

When Is the Best Time to Drink Hot Water?

The best time to drink hot water is first thing in the morning according to experts. Sarah Krieger, a registered dietitian nutritionist from Florida, states this is because “you don't drink while you're sleeping and you wake up already dehydrated. Having water can get you back up to your baseline”.

2015 guidelines in the European Journal of Pharmaceutical and Medical Research by Suchita Patel et al. on the benefits of hot water recommend drinking one or two glasses early in the morning, before brushing teeth. The study notes that it is good to drink one glass at least 15-30 minutes before eating. Drinking hot water before sleep was also recommended by the study. These recommended times are illustrated on the chart below.

Suggested Water Drinking Schedule

Dr. Michael Picco a board-certified doctor in internal medicine and gastroenterology is of the opinion that drinking water after eating aids digestion. He goes on to explain that water and other liquids help break down food so that your body can absorb the nutrients. Water also softens stool, which helps prevent constipation.

Should You Drink Hot Water Daily?

Yes, you should drink hot water daily. This is because drinking hot water increases blood circulation, alleviates stress and inflammations, helps decrease complications associated with cramps and indigestion, aids in weight loss, and encourages detoxification.

However, it can also disrupt the body’s thirst sensors and cause dehydration, requiring increased awareness of hydration needs, especially during and after exercise. Hot water helps with lowering body temperature after extreme exercise and boosts metabolism.

The European Journal of Pharmaceutical and Medical Research gives a word of warning: “always check with your prescribing physician before drinking warm water if you’re on any medications because that could impact the efficacy of your medications”.

What Kinds of Water Can You Drink Hot?

You can drink all types of potable water hot. This includes tap water, spring water, mineral water, reverse osmosis water, artesian water, distilled water, well water, mist water, rainwater, and all types of arctic water including iceberg water. “Potable” water is a keyword here as, depending on the specific source of the water, you may need to filter or boil it first to ensure it is safe.

What Are the Reasons People Prefer Drinking Hot Water?

The reasons people prefer drinking hot water are that they believe it has health benefits. Science does support that drinking hot water improves digestion, aids weight loss, and helps you stay hydrated.

Ayurvedic medicine, traditional Chinese medicine, and Japanese water therapy also believe that drinking hot water produces health benefits, some of which are supported by science and others are not. The map below shows some regions where warm or hot water has traditionally been consumed for health reasons.

Regions Where Hot Water is Consumed for Health
 

Chinese medicine considers hot or warm water essential for maintaining the body’s balance. Chinese culture strongly promotes drinking a glass of warm water in the morning to help kick-start the digestive system and improve circulation. The theory behind this is that increases in blood circulation help remove or dilute waste material in the body.

The Chinese consider hot water a cure for everything from a sore throat to painful muscle cramps, whereas cold water is believed to slow down organ function and cause muscle contractions. Some Chinese people also believe that mixing hot food with cold water can create an imbalance of temperature in the body and thus prefer drinking hot water over cold.

Chinese people have been drinking hot water since at least the 4th century B.C. This is so entrenched in the mindset that it was included in the 1934 Nationalist Guidebook Essentials of the New Life Movement, a collection of doctrines and principal beliefs. aimed at promoting hygienic and behavioral attitudes to revitalize the Chinese way of life. A typical factory in China has lockers for the workers to store their belongings as well as racks to keep the thermos of hot water that almost every worker carries.

Ayurveda, a natural system of medicine that originated in India more than 3,000 years ago also recommends drinking water that is warm to hot. According to Ayurveda, regularly drinking warm to very warm water, especially in the morning, can heal your body, improve digestive power and reduce the metabolic waste that can build up in the immune system.

Japanese Water Therapy involves drinking very warm water on an empty stomach supposedly to cleanse the system and heal a variety of conditions. Advocates of this system claim that cold water is harmful because it can cause fats and oils in food to harden in the digestive tract.


1 comment

  • Kobusingye Margaret

    Thanks


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