Introduction
Uric acid is the end product of the metabolism of proteins and purines in the body. Purines are part of DNA and are either ingested through food or released after the normal destruction of body cells and their replacement. Normally, there is a balance between the production and excretion of uric acid. However, an increase in its levels in the blood, a condition referred to as hyperuricemia, can be observed, either due to increased production or due to reduced excretion, which is usually the result of some kidney disease. In recent years, the number of people with hyperuricemia has been increasing, mainly due to the adoption of a more Western-style diet based on excessive consumption of red meat, processed carbohydrates (white grains, pastries, cakes, cookies, etc.), sweets and soft drinks, as well as a reduced intake of fruits and vegetables. More specifically, based on data published by NHANES (National Health and Nutrition Examination Survey) up to 2016, 20.2% and 20.0% of men and women in the global population, respectively, had elevated blood uric acid levels. People with hyperuricemia often develop crystals in the joints (gout) and in the kidneys (nephrolithiasis). In addition, this condition often coexists with other diseases such as metabolic syndrome, hypertension, cardiovascular disease and excess weight.
Risk factors
There are several factors, environmental and non-environmental, that affect blood uric acid levels. These include:
- Gender: Men are more likely to develop hyperuricemia than women, as estrogen plays a protective role by promoting the removal of uric acid from the kidneys. Postmenopausal women have the same risk of developing hyperuricemia as men, due to reduced estrogen production.
- Family History: The presence of family members with hyperuricemia or gout is directly related to blood uric acid levels.
- Lifestyle: Purines from the diet are responsible for 1/3 of the daily production of uric acid.
- Obesity: Uric acid levels increase with an increase in the Body Mass Index (BMI) of individuals and the development of overweight and obesity.
- Metabolic Syndrome: Overweight, insulin resistance, increased levels of triglycerides and cholesterol in the blood, as well as increased blood pressure that characterize metabolic syndrome tend to increase uric acid levels in the blood.
- Chronic kidney disease: Although uric acid is not produced to a large extent, its levels increase in the blood due to a reduced ability of the kidneys to remove it from the body.
- Medication: Some medications can cause an increase in uric acid in the blood. These include diuretics, aspirin, epinephrine, norepinephrine and cortisone.
Dietary management
Most of the above risk factors, such as obesity and metabolic syndrome, are the result of individuals’ dietary habits, affecting the risk of developing the disease. Changing these dietary habits is important to maintain or even improve blood uric acid levels. Although the exact purine content of foods is not clear, as it is also affected by processing processes, there are some foods that have been shown to have increased uric acid content and should be avoided or even prohibited by people with hyperuricemia.
Forbidden foods:
- All processed meats (cold cuts, sausages), offal, game meats (hare, rabbit and duck) as well as sauces derived from them.
- Mussels, oysters and scallops
- Herring, sardines, haddock
- Roe
Foods to limit:
- Shrimp, cod, mackerel and sole
- Tomatoes, spinach, mushrooms and asparagus
- Dried and fresh beans
- Almonds
- Ripe fruits, honey and high fructose soft drinks (mainly in the form of corn syrup). Studies show that both natural and added fructose in foods is associated with increased levels of uric acid in the blood
- Alcohol and more specifically beer
Freely consumed foods:
- Starch-based products, namely pasta, rice, bread, toast, cereals, corn and potatoes.
- Dairy products, the preference for low-fat dairy products seems to act protectively due to the proteins they contain and which remove uric acid from the bloodstream.
- Fruits and vegetables, especially fruits with a high vitamin C content such as oranges, strawberries and pineapple, reduce uric acid levels and can help prevent the onset of gout.
- The egg.
Patients with uric acid, in addition to their dietary habits, should also follow a healthy lifestyle. Adequate hydration is recommended throughout the day, especially after some kind of exercise, as well as meeting the daily needs of up to 8 glasses per day for women and 10 for men respectively. In the case where the body is dehydrated, uric acid in the blood is increased and the breakdown of purines is favored, since the body’s cells are destroyed more quickly, and their removal by the kidneys is not favored. To relieve joint pain, which is a frequent characteristic symptom of patients with gout, aerobic exercise is mainly recommended on a daily basis. Aerobic exercises include walking, swimming and cycling. The recommended duration is the same as that recommended for the general population, namely 150 minutes per week. These activities are considered the most friendly to the joints, since there is not so much burden and therefore the risk of injury. In case the symptoms of gout are very intense, it would be advisable to avoid any form of movement and to follow a physiotherapy program until the symptoms subside.
Conclusion
In conclusion, uric acid is a product of metabolism that directly affects the health profile of individuals and special emphasis should be given, especially to individuals with an existing predisposition due to gender, family history or taking specific medication. The adoption of a balanced diet that excludes specific foods and by extension a lifestyle based on good hydration and exercise is capable of positively affecting both the health and quality of life of individuals.
