Up to 70 percent of the human body consists of water. It is present on both the inside and outside of the cells.
Water or fluid retention refers to an excessive buildup of fluid in the circulatory system, body tissues, or cavities in the body.
It can occur in many different areas of the body and for different reasons. This MNT Knowledge Center article will look at the causes of water retention in each area individually.
Fast facts on water retention:
- Up to 70 percent of the body is made of water.
- Symptoms of water retention include stiff joints and skin discoloration
- Treatment includes diuretic pills and keeping the legs raised 3 to 4 times a day.
Symptoms will occur in the affected area in which water is being retained.
These symptoms include:
- discolored skin
- areas of skin that stay indented when pushed in with a finger, known as pitting edema
- aches and tenderness in the limbs
- stiffness in the joints
- weight gain
Treatment for water retention depends on several factors, including the root cause. However, most cases will resolve without treatment.
Visiting a doctor would only be necessary if symptoms do not clear up.
They may then prescribe medications, such as diuretics. These cause the kidneys to remove fluid from the blood. A limited course is recommended, as taking them for too long can lead to dehydration, worsen water retention, and cause kidney damage.
Treatment for leaky capillaries
In this case, tissues retain both water and protein. Diuretics would cause the kidneys to remove fluid faster from blood, while the protein in the tissue spaces would continue drawing fluid from the blood into the tissues. This results in dehydration of the blood. Eventually, diuretics can make water retention worse.
A doctor will treat the cause of the leaky capillaries. As they are often linked to a protein problem, medications will be given that help to break up the protein in the tissue space.
It can be difficult for a doctor to distinguish between water retention caused by leaky capillaries and retention due to other causes.
There are many possible causes of water retention.
A complex system of hormones and hormone-like substances called prostaglandins are used by the human body to regulate water levels. This means that excess water can be excreted quickly from the kidneys in the form of urine. Likewise, drinking less fluid means that less urine will be produced.
Water retention can occur due to changes in this regulatory system, or a range of other triggers.
Fluid rich in nutrients, vitamins, and oxygen continuously passes from tiny blood vessels into surrounding tissues. This fluid is known as interstitial fluid.
Interstitial fluid nourishes cells and eventually makes its way back to the capillaries. Water retention may occur if the pressure inside the capillaries changes.
Water retention is also possible if the capillary walls become too leaky. If something goes wrong with pressure or the wall becomes too leaky, excess liquid will be released into the spaces between cells.
If too much fluid is released, more of it will remain in the tissues, rather than returning to the capillaries, resulting in swelling and water retention.
The lymphatic system
The lymphatic system drains a fluid called lymph from tissues and empties it back into the bloodstream. However, if too much fluid is released in the first place, the lymphatic system can become overwhelmed. It is unable to return fluid fast enough, and this builds up around the tissues.
Sometimes, if the lymphatic system is congested, the rate at which fluid is returned to the bloodstream may change. This means that fluid might remain in the tissues, causing swelling in various parts of the body, including the abdomen, ankles, legs, and feet.
Normal pressure within blood vessels is partly maintained by the pumping force of the heart. However, if the heart starts to fail, there will be a change in blood pressure, which often results in serious water retention.
Typically, the legs, feet, and ankles will swell. Fluid will also build up in the lungs, giving the patient a long-term cough or breathing difficulties.
Blood is filtered through the kidneys. Waste, fluids, and other substances are extracted and cross into tiny tubules. From there, the bloodstream reabsorbs anything the body can reuse. Any waste is excreted in urine.
In most cases, kidneys can eliminate all waste materials that the body produces. However, if the blood flow to the kidneys is affected, problems can occur. For instance, in kidney failure, waste material, including fluids, cannot be eliminated from the body properly, resulting in fluid retention.
The weight of the uterus on the major veins of the pelvis can cause a buildup of fluid in the body during pregnancy. In most cases, it is nothing to worry about and generally resolves after the baby is born.
Exercise helps the leg veins return blood to the heart. If the blood does not circulate often enough, it will begin to accumulate in the legs, causing higher pressure in the capillaries.
This higher pressure means that fluid will leave the capillaries at a faster rate. The increased pressure also makes it harder for fluids to come back later on.
Exercise is necessary to stimulate the lymphatic system to carry out its function of regulating overflow, bringing fluids back into the bloodstream at rates that may regulate body water levels. Very long periods of physical inactivity, such as a long-haul flight, increase the risk of water retention.
During a long-haul flight, even minor physical movements, such as standing up on tiptoes a few times, rotating the ankles, and wiggling the toes, can help reduce fluid retention.
Humans require a certain level of proteins for effective water balance. An individual with severe protein deficiency may find it harder to get the water from the tissue spaces back into the capillaries. The enlarged abdomen of someone who is starving is mainly caused by a lack of protein in their diet.
When inflammation is present in the body, histamine is released. Histamine causes the gaps between the cells of the capillary walls to widen, making them leakier. The aim is to make it easier for infection-fighting white blood cells to quickly get to the site of inflammation.
However, if the inflammation persists for a long time, water retention can become a problem.
Medication-caused water retention
Some medications can cause water retention, including:
- Drugs that contain estrogen: These can reduce water retention. Examples include birth control pills or hormone replacement therapy (HRT).
- Non-steroidal anti-inflammatory drugs (NSAIDs): These are medications with pain-reducing, fever-reducing effects. In high doses, they are actually effective in reducing inflammation. Examples include aspirin, ibuprofen, and naproxen.
- Beta-blockers: These are used to treat abnormal heart rhythms and prevent tachycardias.
Premenstrual water retention
This can cause bloating and breast tenderness. Experts say this is due to hormone imbalances and some nutritional factors, including:
- Malnutrition and bad diet: A poor diet low in protein result in low levels of albumin, which may also play a part in developing water retention.
- Salt, or sodium: Sodium-rich foods may cause water retention.
- Allergies: Some foods and insect bites may cause edema in susceptible people.
- Thyroid disease: People with a disorder of the thyroid gland commonly experience water retention.
There are some solutions to water retention that can be carried out at home. The effectiveness of each depends on the location and severity of the condition.
Keeping the legs raised for three or four times each day can help to improve circulation and shift fluid. Sleeping with the affected limb raised above the level of the heart can also be helpful.
A massage may also help the affected area when stroked firmly in the direction of the heart. This may help move the fluid. It is important that the hand movements do not cause pain.
There are a few ways to manage water retention through the diet.
reducing the intake of sodium, or salt
more magnesiumfrom different sources, such as beans, nuts, whole grains, and leafy greens
more foods that contain vitamin B6, such as bananas, walnuts, and potatoes
The following steps may help reduce or prevent the symptoms of water retention:
- weight loss
- regular exercise
- wear supporting stockings if the water retention occurs in the lower limbs
- avoid sitting and standing still for too long
- take breaks from sitting and walk regularly when completing long journeys by car, train, boat, or plane
- avoid extreme temperatures, such as hot baths, showers, and saunas
A balanced, healthy lifestyle will help keep water retention to a minimum.