Beware of this useful yet dangerous substance

What are purines?

Purines are natural substances found in almost all foods and perform important functions in the body. They are essential for cell structure and function because they are components of genetic information and are involved in the formation of new cells. The body can synthesise purines itself and also takes them in through the diet, particularly from animal products.

When purines are broken down, uric acid is produced, which is normally excreted by the kidneys. If this process is disturbed, for example in people with impaired kidney function or a predisposition to gout, uric acid levels in the blood can rise. People with elevated uric acid levels or kidney disease should avoid purine-rich products to avoid placing additional strain on the body. A conscious diet can help minimise symptoms in these cases.

What happens to purines in the body?

Purines play important roles in the human body as building blocks of DNA and RNA as well as of enzymes and molecules involved in energy metabolism. They are taken in through food and are also synthesised by the body. They are also produced as a by-product of cell breakdown. Since the body cannot excrete purines directly, they are broken down in several steps to uric acid.

The majority of uric acid is excreted via the kidneys, with a smaller proportion passing through the gut. However, if excretion is insufficient or too many purines are produced, blood uric acid rises. At a level of around 6.8 mg/dl, uric acid can crystallise. These crystals tend to deposit in cooler areas of the body such as joints or tendons and can cause inflammation. Typical outcomes include conditions such as gout or painful joint inflammation.

The balance between purine intake, production and breakdown can be disturbed by genetic factors, illnesses, certain medications or diet. Purine-rich foods such as meat, legumes and certain types of fish, as well as excessive alcohol consumption, promote increased uric acid production. Kidney dysfunction can also impair uric acid excretion.

Uric acid can act as an antioxidant and protect against free radicals. However, a concentration that is too high is detrimental to health. To minimise the risk of gout and other complications, uric acid levels should be monitored regularly and regulated by dietary or medicinal measures.

Which foods contain purines?

They occur in many products, particularly in animal products. Meat and processed meat products are particularly high in purines, as are fatty meats such as goose or pork. Processed meats like sausages, salami and mettwurst also contain significant amounts of purines. Fish and seafood are likewise among purine-rich foods. 

Plant-based products such as legumes — especially peas, beans and lentils — also contain purines. Soy and soy products such as textured soy are affected too, though to a somewhat lesser degree.

Another important factor is the consumption of alcoholic beverages, especially beer, which can significantly raise uric acid levels, as well as stronger alcoholic drinks such as wine and spirits. Non-alcoholic beer is not free of purines either and should be consumed in moderation. Yeast products such as yeast extract and instant bouillon cubes also have a high purine content and should be used with consideration in the diet.

Which foods do not contain purines?

For gout it is important to include low-purine foods in the diet, as they can help lower uric acid levels. Purines are components of cellular DNA and occur in almost all foods, though in varying amounts. However, there are many foods that are low in purines and therefore well suited to a gout-friendly diet.

Low-purine foods include many fruits and vegetables. Fresh fruits such as apples, berries (e.g. strawberries and blueberries), plums and apricots are particularly recommended. These fruits not only contain few purines but also many vitamins that can support recovery in gout. Some fruits like pears and persimmons, which have a high sugar content, should however be eaten in moderation.

Dairy products are also a good source of low-purine foods. Milk, low-fat yogurt, quark and cheese contain virtually no purines. Low-fat variants are especially recommended as they can additionally help lower uric acid. Eggs are also considered low in purines, provided they come from humane rearing. Wholegrain products such as wholegrain bread, brown rice and wholegrain pasta are also a good choice because they are low in purines and provide valuable fibre. Nuts such as almonds, walnuts and hazelnuts are likewise recommended, as they are low in purines and supply healthy fats.

Industrial processed foods, convenience meals and sugary products should be avoided, as they often contain high amounts of unhealthy fats and sugars that can negatively affect uric acid levels. In particular, high-fructose corn syrup, found in many convenience products, is problematic in gout.

How are gout and diet linked?

Gout is caused by a high level of uric acid in the blood, which can deposit in the joints as painful crystals. Diet has a decisive influence here, since certain foods and drinks affect uric acid levels. In particular, a diet high in fat, low in fibre and with excessive added sugars can contribute to the development of gout, as it promotes inflammatory processes and reduces the body's ability to excrete uric acid.

A specific focus on nutrient-rich, plant-based foods that are high in antioxidants and have anti-inflammatory properties helps regulate uric acid levels and prevent gout attacks. At the same time, combining fibre, healthy fats and adequate fluid intake can help prevent uric acid accumulation.

How best to manage purines: useful tips

• Choose lean meats without skin or fat, as they contain fewer purines. Avoid offal like liver and kidneys, which are particularly high in purines.
• Limit consumption of sardines, sprats and herring. Instead, favour lean fish such as plaice or smoked pollock.
• Prefer plant-based protein sources such as quinoa or amaranth, which contain fewer purines.
• Choose plant-based alternatives. Particularly recommended are bell peppers, tomatoes, kohlrabi, cucumbers, carrots and pumpkin. They contain almost no purines and provide valuable nutrients. Bitter salads such as arugula or dandelion are also a good choice.
• Sugary soft drinks, sodas and fruit juices with added fructose can raise uric acid levels. Instead opt for water, unsweetened teas and diluted fruit spritzers.
• Avoid fatty dishes and favour low-fat preparation methods such as grilling or steaming. Reduce consumption of convenience foods.
• For cooking, plant oils like olive oil and linseed oil are recommended because they are purine-free and contain healthy fats. 
• During cooking, purines can migrate into the cooking water, which should then be discarded to reduce the purine content.
• Fruits and fruit juices containing vitamin C can lower uric acid levels. Enjoy them in moderation.
• Drink at least two litres of water or other low-purine beverages daily to promote uric acid excretion.
• Maintain a healthy body weight to reduce the risk of gout. Lose excess weight gradually and avoid sudden dieting.
• Have a plan drawn up by a doctor or dietitian that takes your specific needs into account.

Purines are necessary for various bodily functions but in excessive amounts can cause health problems such as gout. A balanced diet and control of purine intake help prevent health issues.