The excess consumption of some foods is harmful and damaging for the kidneys. In this article, we will discuss the most harmful foods for kidneys and foods to avoid with kidney disease.
What Are Kidneys?
Kidneys are the natural filtering system of the body. These bean-shaped organs purify the blood and pass the waste products as urine. The kidneys perform various important functions like:
- They produce hormones that help in the production of red blood cells.
- They regulate blood pressure and enhance bone health too.
- Kidneys help in the removal and excretion of waste materials from the food and drugs.
- Kidneys maintain the overall fluid balance.
- They prevent the excretion of minerals and other important components in the urine.
As kidneys perform so many vital functions in the body, any damage caused to this pair of organs can create a havoc in the body.
Link Between Diet and Kidney Health
Kidneys are the filters of the body. Any damage caused to these natural filters of the body may lead to accumulation of toxic substances in the body. It may further affect the health negatively. Therefore, the foods we eat and drink have a huge impact on the natural filtering system of the body.
Eating machine-made and processed foods may exert an additional pressure on the kidneys, damage the kidney cells and hamper the overall functioning of the kidneys.
A kidney-friendly diet includes natural and wholesome foods, low sodium and sugar intake, moderate protein intake, restriction of foods containing chemicals, preservatives and artificial colors and flavors.
Harmful Foods for Kidneys
Here is how improper diet and lifestyle habits can damage the kidneys:
High Sodium Intake
Eating a high sodium diet for a prolonged period of time causes enlargement of the kidneys and their cells.
It further leads to fibrosis of the kidneys, which results in hardening of the kidneys, loss of kidney function, ultimately leading to kidney failure.
Excess sodium intake also reduces the ability of the kidneys to filter the waste products.
Moreover, a high sodium diet may blunt the effect of drugs that help in the management of hypertension. This results in high blood pressure, which further damages the kidney.
Studies have further observed that restriction of sodium intake is an important step in preventing the kidney damage.
Foods high in sodium include:
- Canned meats
- Frozen foods
- Canned beans
- Packaged foods
- Salad dressings
- Ketchup and chutney
- Ready-to-eat foods
- Broths and stocks
- Processed foods (1, 2)
Consuming drinks high in sugar increases the risk of obesity. All we get from sugar is ‘calories’ and no nutrients.
An interesting study found that drinking more than 2 sugar soft drinks per day is associated with faster kidney function decline.
It reduces the glomerular filtration rate, which is an important indicator of kidney function. Such a reduction lowers the ability of the kidney to excrete waste substances from the body.
Furthermore, carbonated beverages are also linked to kidney stone formation. Such beverages are acidified with phosphoric acid, that causes urinary changes, which promote kidney stones.
Therefore, it is best to restrict the intake of carbonated beverages and diet colas. White or refined sugar should be replaced with organic honey or low glycemic index organic coconut sugar. (3, 4, 5)
High Protein Diet
One interesting study reported that daily red meat consumption over years may increase the risk of chronic kidney disease. Whereas intake of white or lean meat and dairy proteins appear to have no such effect and plant proteins may be renal protective.
High protein diet can add stress to the kidneys because the kidneys need to work harder to clear the metabolites of protein from the body.
A higher proportion of calories from protein in healthy adults may cause kidney injury and increase the glomerular filtration rate (GFR). This may lead to excretion of important nutrients that are otherwise required by the body.
Healthy sources of protein include:
- Pulses, legumes and beans
- Soy and soy products like tofu
- Low-fat milk and milk products
- Chicken and turkey
- Fish and shellfish
- Nuts and oilseeds
Eating Unhealthy Fat
It is very well known that eating unhealthy fat is bad for the heart, but this unhealthy fat can even damage your kidneys.
Research has found that hyperlipidemia is associated with progressive kidney failure. Dietary fat can influence kidney structure and function.
The glomerulus is a structure present in the kidney that filters the blood to form the urine. Eating a diet rich in saturated fat reduces glomerular number and size. This interferes with the filtration of blood, which results in accumulation of toxic substances in the blood. This can be dangerous and life-threatening.
Besides this, high intake of saturated fat causes albuminuria, which is excess protein in the urine. A healthy kidney doesn’t let the proteins pass from the blood into the urine. But, damage caused by saturated fat to the kidneys causes loss of proteins into the urine. Sources of saturated fat include:
- Processed Meats
- Palm oil
- Whole milk
- Cakes, pastries and other bakery products (8, 9)
So, you should take whole milk, butter and creams in moderate. Other foods listed above should be limited or stopped.
Cigarette smoking is injurious to health. It not only affects the lungs, but it also exerts a harmful effect on the kidneys.
Scientific studies have reported that cigarette smoking is a risk factor for the development and progression of chronic kidney disease. Smoking induces a direct damage to the kidney cells and filtering units of the kidneys.
It deteriorates the kidney function by increasing the risk of albumin and protein excretion into the urine.
Smoking is associated with elevated levels of inflammatory markers, suggesting inflammation may contribute to kidney dysfunction, says research.
Inflammation increases the generation of reactive oxygen species, which damage the kidney cells. It also affects the arteries of the kidneys by damaging the inner lining and promoting the formation of plaques in the arteries. This obstructs the flow of the oxygen and nutrient-rich blood towards the kidneys, which may lead to kidney damage. (10)
Acute as well as chronic alcohol consumption can compromise kidney function. Alcohol directly affects the kidneys by altering the structure and function of this pair of organs.
Excess alcohol consumption causes enlargement of the kidney tubules. An animal study observed that alcohol-fed group experienced kidney swelling and reduced kidney function.
Alcohol consumption may also lead to the excretion of essential ions and electrolytes. This happens because alcohol intake damages the kidneys, which reduces the ability of the kidneys to reabsorb the important ions and electrolytes. Loss of such important components causes their deficiency, which further exerts a negative effect on the body.
An important function of the kidneys is to maintain the homeostasis of the body. Alcohol consumption can cause an imbalance and disturb the homeostasis. This can affect the way the body functions and reacts.
Individuals with diabetes mellitus and hypertension are at an increased risk for kidney damage. Alcohol consumption in such individuals further pushes them towards faster kidney dysfunction.
Being physically active not only has an impact on the on the outer structure of the body, but it also affects the health of the inner body organs.
Low physical activity and sedentary behavior are associated with poor kidney function and kidney damage, says research. A sedentary behavior is associated with adverse kidney function and kidney damage, whereas physical activity is associated with more favorable kidney function and less damage.
Studies have also found that uninterrupted sitting periods of 30 minutes or more can negatively affect kidney function.
A sedentary lifestyle may contribute to the development of endothelial dysfunction, that is damage to the inner lining of the blood vessels of the kidneys. It also reduces the density of the capillaries, which results in poor flow of oxygen and nutrient-rich blood towards the kidneys.
Besides this, a sedentary lifestyle is associated with an increased risk of hypertension, type 2 diabetes mellitus and dyslipidemia. All these health conditions have a direct negative impact on the kidney function. (11)
Low Water Intake
Drinking water in moderate amount helps in the clearance of excess sodium and toxins from the body. The build-up of waste products can cause damage to the kidneys.
Not drinking enough water can make the urine concentrated with minerals and waste products. This increases the risk of kidney stone formation.
Mild dehydration can even reduce the flow of blood towards the kidneys and cause kidney damage. Some studies have shown that frequent mild dehydration may lead to permanent kidney damage.
Therefore, it is important to keep yourself hydrated. However, individuals with low kidney function or kidney failure need to ask their doctor about their fluid intake. (12)
Overuse of Drugs
Anything in excess is unhealthy. Though the drugs may heal your health problems, they can harm your kidneys.
Drugs may have a direct nephrotoxic effect or elimination of drugs through the kidneys can damage them.
Certain drugs scar the kidney’s blood vessels and cause injury to this pair of organs. Such an injury can lower the kidney function.
Prolonged administration of such drugs, especially painkillers can cause structural abnormalities and renal dysfunction.
An overdose of drugs increases oxidative stress in the kidneys and destructs the kidney cells. Certain drugs are even responsible for several renal complications.
Hence, individuals must always consult their doctor before self-prescribing any drug. (13)
Article edited by Dr. Jagdev Singh.