Have we found a way to combat cancer and enable space travel using… “light” water? You couldn’t tell the difference between tap water and deuterium-depleted water—not even with a microscope. Still, the other one promises to protect you against cancer, radiation, and more. We decided to see if it may be the future of health and wellness or if it’s just another fad.

What is Deuterium-Depleted Water?

A water molecule contains 2 atoms of hydrogen and 1 atom of oxygen (H2O).

Hydrogen exists in different forms, called isotopes, depending on the number of neutrons–neutral particles–in its core. The isotope without neutrons (H – protium) is the most abundant, but water molecules also contain a small amount of deuterium (D or hydrogen-2).

Deuterium, having 1 neutron, is about 2 times heavier than regular hydrogen. Thus, we call water with reduced deuterium content “light water” or deuterium-depleted water (DDW).

The natural deuterium levels in water depend on different factors such as [R+, R]:

  • Temperature—warm waters contain more deuterium
  • Altitude—high mountain waters contain less deuterium
  • Source—freshwaters contain less deuterium than oceans
  • Latitude (distance from the equator)—water on the poles has the least deuterium

A standard concentration of deuterium in water is 150 ppm (parts per million) or 1 atom of deuterium per 6400 atoms of regular hydrogen. In other words, each quart (or liter) of water contains only a few drops with deuterium [R, R].

Deuterium-depleted water (DDW), in comparison, contains 1-120 ppm of deuterium [R, R+, R].



  • Stimulates cell growth and recovery
  • Boosts detox and metabolism
  • May help fight cancer
  • May prevent heart disease and depression
  • May protect the liver


  • Not well-researched
  • May be toxic to stem cells
  • Production is expensive and energy-consuming

Why Deuterium-Depleted Water?

Humans and all life on earth adapted to relatively stable amounts of rare isotopes like deuterium. Anything that increases their levels can set this balance off [R].

High concentrations of deuterium in water can impair the growth and division of human stem cells. They lose energy-generating activity, change shape, and become scarred [R].

In animals, heavy water (with more deuterium) can damage the nervous system and cut the number of blood cells [R].

Interestingly, deuterium levels are 5 times higher on Mars than on Earth. Shrimps and bacteria exposed to these conditions grow slower and live shorter. Apparently, it is something any future interplanetary space missions would need to take into account [R].

Usually, too much or too little of anything is not good, and scientists assumed the same would be true for deuterium. High levels are bad but extremely low levels probably can’t be good either, right? To their surprise, it turned out that low levels of deuterium might not have typical negative effects–on the contrary [R].

Initial findings led scientists to closely examine the health effects of deuterium-depleted water in search of its potential uses.

How Does It Work?

Unlike heavy water, deuterium-depleted water (DDW) may have positive health effects.

In human and animal trials, it blocked the expression of cancer-promoting genes and inhibited the growth of cancer cells [R, R, R, R].
In rats, DDW was able to decrease deuterium concentration in blood (by 35%) and tissues (by 15%). As a result, the rats’ metabolism and immunity improved. It also protected them from oxidative stress and boosted their growth [R, R].

In another animal study, DDW stimulated energy and detox pathways [R].

Human and animal cells exposed to this water were more active, grew faster, and suffered less genetic damage [R, R, R].

Based on studies on bacteria, DDW might also work by triggering hormesis–acting as a mild stressor that increases resilience to bigger stressors and shifts functioning to a state of enhanced performance. This is still largely speculative, though, as it relies on the response of bacteria, not humans [R].

In summary, deuterium-depleted water may:

  • Block the spreading of cancer cells
  • Boost the immune system and metabolism
  • Protect from oxidative damage
  • Stimulate cell growth and recovery
  • Activating hormesis

Manufacturers and retailers claim deuterium-depleted water can treat diabetes and high blood pressure, enhance sports performance and strength, and combat the effects of stress and aging. However, limited evidence supports only a fraction of these claims.

Can Deuterium-Depleted Water Fight Cancer?

Only the anti-cancer effects of deuterium-depleted water have been studied in humans, aside from being researched in animals and cells. Although clinical studies have been carried out, many of them suffer from glaring flaws. With this in mind, their findings should be viewed with healthy skepticism.

Clinical Studies

In a clinical study on 44 patients with prostate cancer, the addition of deuterium-depleted water (DDW) to standard treatment [R+]:

  • Increased the chance of partial treatment success by 7 (7 vs. 1 patient)
  • Reduced prostate volume
  • Relieved unpleasant urination symptoms
  • Cut the levels of PSA, a marker of disease progression
  • Increased 1-year survival 4.5 times (2 vs. 9 deaths)

The same research team conducted an observational study on 91 prostate cancer patients (46 with metastases) who consumed deuterium-depleted water. Their average survival time was 11 years, but it’s unsure whether DDW contributed to the results [R+].

Although the above study had flaws, it did include a control group that drank equal amounts of regular water. Both groups also received the same conventional treatment.

In another clinical trial, 129 patients with lung cancer consumed DDW along with their conventional treatment (chemo and radiation). On average, they survived 2-4X longer than expected, especially female patients (74 months vs. 26 months). However, this study did not include a control group that drank regular water. Strong placebo effects are a possibility [R].

An observational study followed 232 women with breast cancer who replaced “normal” water with DDW for at least 3 months. Patients in the early stage survived 18 years on average, but most patients with metastases didn’t reach a 5-year survival. Those who took at least 2 rounds of DDW treatment (>6 months) survived the longest (~24 years) [R].

According to one review of clinical trials, drinking deuterium-depleted water could [R]:

  • Block the growth of cancer cells
  • Prolong the survival of patients
  • Improve their quality of life

Being an observational study, there is no way to tell which effects were due to low deuterium, which were a placebo effect, and which were a result of other supplements, factors, or interventions.

That said, all the above studies have small sample sizes and other serious flaws that cast doubt on their findings (see “Limitations and Caveats” for more details).

Case Reports

According to case reports, adding deuterium-depleted water for at least 3 months to standard treatment helped 4 lung cancer patients with brain metastases. This combination removed metastases in 2 patients and reduced them in 1 patient. It also caused remission or shrank lung tumors in all patients [R].

Animal Studies

One review of animal studies revealed that deuterium-depleted water (DDW) could kill cancer cells and fight different types of cancer in dogs, cats, and lab animals [R].

In studies on mice with various types of cancer, deuterium-depleted water [R, R, R] :

  • Blocked cancer-promoting genes
  • Eliminated or reduced the tumors
  • Increased the animals’ lifespan

Cell Studies

Cell studies support the cancer-fighting properties of deuterium-depleted water. It prevented the growth of human cancer cells, including [R, R, R, R, R, R]:

  • Prostate cancer cells
  • Colon cancer cells
  • Breast cancer cells
  • Stomach cancer cells
  • Lung cancer cells
  • Nose and throat cancer cells

In one study, deuterium-depleted water couldn’t block the growth of cancer cells on its own, but it boosted the effects of chemotherapy [R].

The above findings point to the anticancer potential of deuterium-depleted water, but they are far from conclusive. Well-designed clinical trials should examine this further.

Potential Health Benefits with Limited Evidence

The following health effects of deuterium-depleted water have only been examined in animal and/or cell studies.

1) May Protect Against Radiation

Deuterium-depleted water (DDW) was able to protect mice from the damaging effects of radiation. It boosted their immune system and the production of blood cells. As a result, animals had a 36% higher chance of survival (65% vs. 25%) [R].

Another study on mice confirmed this effect, especially in combination with polyphenols [R].

In cell experiments, deuterium-depleted water strengthened and helped repair DNA, protecting it against radiation-induced damage [R+].

Anticancer and radioprotective effects of deuterium-depleted water may improve cancer treatment response, on the one hand. But on the other, these properties may also enable future space travel.

Any astronauts venturing to Mars would be exposed to extreme levels of radiation in the flight, and high deuterium levels on the planet. Although not commonly talked about, this is an exciting area of research. Scientists have considered that ensuring a deuterium-depleted water supply may play a crucial role in protecting the crews from cancer in future space missions to Mars [R, R].

2) Liver Protection and Detox

Animal studies hint at the ability of deuterium-depleted water (DDW) to protect and stimulate the liver. In animals, DDW was able to [R, R, R, R]:

  • Repair oxidative damage in the liver
  • Boost the production of protective compounds, such as glutathione
  • Decrease the levels of inflammatory molecules (COX-2, PGE2)
  • Prevent liver infection and injury
  • Boost detox pathways

In worms, it was able to reverse the toxic effects of manganese (Mn) and restore normal lifespan [R].

4) Mood & Memory

In a study on mice, deuterium-depleted water (DDW) reduced signs of depression and stress. Interestingly, it stimulated the brain’s memory center and increased wakefulness. These effects were similar to SSRI (antidepressant) drugs [R].

In rats, drinking deuterium-depleted water enhanced long-term memory, but it didn’t impact short-term memory and movement [R].

5) Diabetes and Heart Disease

In healthy rats, deuterium-depleted water (DDW) [R]:

  • Cut the levels of cholesterol and blood lipids
  • Improved insulin secretion
  • Protected the heart

In rats with high blood pressure, however, it only slightly increased insulin production. More research is needed to clarify this potential benefit.

Side Effects & Precautions

In clinical trials, deuterium-depleted water (DDW) had no major side effects. Out of 44 patients with prostate cancer, only 1 patient experienced nausea and weakness due to drinking it [R, R+].

Observations didn’t associate any risk with drinking deuterium-depleted water long-term [R, R+].

However, in one cell study, deuterium-depleted water was toxic to human stem cells in the long run. This study confirmed that the best way to store stem cells is an environment with typical deuterium levels–but it does not provide us with much toxicity information when it comes to living beings [R].

Studies haven’t evaluated the safety of deuterium-depleted water in childhood, pregnancy, and lactation. These sensitive groups should stay on the safe side and avoid consuming it.

Ultimately, the long-term effects of drinking deuterium-depleted water are still unknown. Large clinical studies would be needed to determine them.

Safety for Pets

In different animal studies, deuterium-depleted water had no significant side effects. It was also safe for cats and dogs. In Hungary, deuterium-depleted water is a veterinary addition to cancer treatment. However, the data are still very limited [R+, R, R, R].

Drug Interactions

Researchers reported no drug interactions of deuterium-depleted water in clinical trials.

According to one cell study, deuterium-depleted water may impact hydrogen-potassium exchange or the “proton pump”. Popular acid-suppressing drugs, proton-pump inhibitors (PPIs), may thus interact with DDW, but no studies have confirmed this [R, R+].

As reported, this water may possibly enhance the effects of cancer treatment [R, R, R].

Limitations and Caveats

Research on deuterium-depleted water (DDW) is scarce. Most health benefits are limited to a couple of animal or cell studies, and we can’t draw solid conclusions from them.

Clinical trials about the anticancer effects of DDW come with big caveats, such as [R, R, R+]:

  • Lack of a control group–drinking enough regular water alone is very important, while the placebo effect can be powerful (even in people with cancer) [R, R]
  • Suspicious randomization
  • Small sample size
  • Vague interpretation of results

One team of Hungarian doctors have conducted the majority of clinical and animal trials on DDW and cancer. Some of them are involved in DDW commercial production and marketing, which points to a massive conflict of interest [R, R, R, R, R].

Products & Dosage


In clinical trials, cancer patients replaced their daily water intake with deuterium-depleted water (DDW). Doctors calculated the exact dosage depending on patients’ body weight and the concentration of deuterium in DDW [R, R+, R].

The range that will make water “low” in deuterium (D) is quite broad — from 1 to 120 ppm D. Some clinical studies used water with 10-20 ppm D, another gradually decreased deuterium content from 105 to 25 ppm, while the remaining one used water with 65-105 ppm D. In comparison, regular water contains ~150 ppm D [R, R+, R].

Available Products

Only a handful of brands manufacture and distribute deuterium-depleted water. It’s available in 0.5-1.5L bottles with different deuterium concentrations (25-125 ppm).

Prices range from $4 to $20 per liter, with lower concentrations of deuterium being more expensive.

Reviews & User Experiences

User experiences with deuterium-depleted water are limited. There are some dubious claims of successful cancer treatment that seem to promote a particular product.

Deuterium-Depleted Water Production

Deuterium-depleted water is a byproduct of “heavy water” (D2O) production. Heavy water has applications in organic chemistry, drug development, and nuclear reactors.

Mass production requires complex distillation, electrical, or chemical reactions. Up to date, all methods are expensive, consume much energy, and pollute the environment. So-called Girdler Sulfide (GS) process is the most efficient, but it uses toxic chemicals.

A team of Chinese scientists reported a new energy-efficient method that may improve the production of deuterium-depleted water in the future [R].

How to Make Your Own

Deuterium-depleted water (DDW) boils and freezes at slightly higher temperatures than regular water. In theory, you could use this feature to make DDW with partial distillation or freezing: water with deuterium would evaporate slower or freeze faster [R+].

Given that 1 liter of tap water contains only a few drops with deuterium, it’s practically impossible to separate it and make DDW on a small scale.


Deuterium (D) is a heavier form of hydrogen (H) that has 1 neutron in its nucleus. High concentrations of deuterium are toxic to cells and living organisms.

Deuterium concentration in natural water is about 150 ppm (parts per million), which equals a few drops per liter. Deuterium-depleted water, also known as light water, contains less deuterium (1-120 ppm).

Several clinical trials have shown the anticancer potential of DDW, but they all had serious design flaws. According to animal studies, DDW may protect against radiation and liver damage; prevent depression and cardiovascular diseases; enhance long-term memory and detox. In Hungary, veterinarians use it to treat cancer in pets.

Potential applications of DDW range from disease prevention to space travel, but we need much more evidence before jumping into conclusions.


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