Purines, Gout and Huel

What is gout?

Gout is regarded as the most common form of arthritis, affecting approximately 5% of the Western population at some stage of their adult life^[1]. Gout is characterised by causing sharp pain, redness and swelling that is often accompanied by intense heat around the affected joint. The most common affected areas are the joints in the foot, especially the big toe (metatarsophalangeal joint), followed by the knee, elbow, wrist and finger joints^[2]. Gout can flare up quickly and, if untreated, can last for prolonged periods of time and can be debilitating. However, if the attack is treated quickly, symptoms can be minimised^[3].

Acute gout attacks are traditionally treated with pharmaceutical drugs, such as non-steroidal anti-inflammatory drugs (NSAIDs), corticosteroids and colchicine which reduce the painful symptoms and swelling^[4]. However, the most effective and proven methods of gout treatment and prevention are changing dietary habits and increasing physical activity, which can significantly reduce gout onset and flare-ups^[5]. The major causes of gout are excessive consumption of purine-rich foods, high blood pressure and obesity^[6]. Lifestyle changes have been shown to have the highest positive effect on the long-term management of gout, along with a calorie-controlled diet that is abundant in phytonutrients, antioxidants and vitamin C^[4-6].

What are purines?

Purines are naturally occurring compounds found in the body, a lot of foods and some drinks^[7]. Purines include the nucleobases adenine and guanine, which are essential for the formation of RNA and DNA^[8]. Other purines are the nucleotides adenosine and guanosine, hypoxanthine and xanthine which are essential for the production of enzymes such as coenzyme A, adenosine triphosphate (ATP) for energy production, cell transcription, cyclic adenosine monophosphate (cAMP) and nicotinamide adenine dinucleotide (NADH) for cell signalling and antioxidant reactions and the synthesis and oxidation of fatty acids^[8].

Another common dietary purine is caffeine which is chemically related to adenine and guanine. However, research has indicated that those who regularly drink coffee are at no greater risk of developing gout^[9]. Research even suggests that moderate coffee consumption is associated with a reduced gout risk, particularly with regular ingestion of fully-caffeinated coffee due to the antioxidant content and caffeine’s effect on circulation^[10].

A moderate purine intake is key to the maintenance of normal uric acid levels for those prone to gout. Frequent and high intakes of purine-rich foods enhance serum uric acid levels, which is involved in the process of gout^[11].

What is uric acid?

The cause of gout stems from having too much uric acid circulating in the bloodstream. Uric acid is an important antioxidant that helps to prevent damage caused by free radicals, and a continuous supply of uric acid is important for protecting blood vessels^[12]. Uric acid is a waste product that is created from the breakdown of dietary purines. If levels of uric acid are too high for prolonged periods of time, crystals can form within the joint tissues causing them to swell and become painful^[12].

The susceptibility to having elevated blood uric acid levels can develop acutely from inflammation brought on by a common virus or infection^[13], chronically from kidney disease^[14] or can be inherited^[15], all of which lead to the body’s inability to efficiently remove excess acid levels.

Increasing evidence points to gout flare-ups being heavily influenced by lifestyle and dietary habits^[4-6]. Gout is also more common in people who are overweight and have type 2 diabetes, even when uric acid levels are within the normal range, as excess weight adds additional strain to joints and insulin resistance lowers the tolerance of uric acid^[16].

How diet can impact gout

Diet has a significant role in both causing and reducing the likelihood of suffering further painful attacks of gout. For someone who already suffers from gout or has multiple risk factors, eating a diet that is lower in purines can result in a reduction of gout attacks. The British Society for Rheumatology recommends limiting purine-rich foods and increasing vitamin C intake to protect against elevating uric acid levels^{[17, 18]}.

General dietary guidelines to prevent and manage gout are in line with those of a general healthy eating diet, such as the DASH diet, which is aimed at reducing high blood pressure and creating a cardiovascular health eating style^[19]. The DASH diet is a plan that is rich in fruit, vegetables and whole grains, includes fat-free or low-fat dairy products and encourages the consumption of fish, poultry, beans and nuts^[20].

One of the main risk factors for the onset of gout is being overweight, and studies suggest that just reducing excess body fat and taking the strain off joints, even without lowering the intake of high purine foods, will reduce circulating uric acid levels and therefore reduce gout flare-ups^[21].

Consuming a diet rich in a variety of fruits, vegetables and whole grains has been shown to reduce gout attacks, largely linked to the vitamin and antioxidant content. Carbohydrate-rich foods that are lower in the glycaemic index (GI) have less inflammatory-causing properties^{[17, 21]}. The intake of foods such as processed white bread, cakes, confectionery, beverages containing sugar and products with high-fructose corn syrup are all associated with increased risk and prevalence of gout^[22].

By maintaining optimal hydration, the clearance of circulating uric acid is aided through excretion via the kidneys^[23]. Limiting alcohol consumption is also important to reduce gout attacks, as the metabolism of alcohol increases uric acid production. In addition, large intakes of alcohol can contribute to dehydration, high blood sugar and a build-up of by-products that can cause DNA damage^{[24, 25]}.

Reducing the intake of overly processed animal products and animal fats and avoiding the excessive intake of dairy products has been shown to have a positive reaction to gout flare-ups and risk, even though dairy products have low purine content^[26]. This is also seen by limiting the intake of animal proteins, particularly organ meats^[26]. However, the fatty acids found in salmon, flaxseed, olive oil and nuts have anti-inflammatory benefits and therefore a balanced intake is essential; but, affecting levels differ from person to person^[27].

Whilst some vegetables, for instance asparagus, spinach, peas, cauliflower and mushrooms, are high in purines, these vegetables do not increase the risk of gout or recurring gout attack due to their content of phytonutrients^[28]. Indeed, some people find that foods such as citrus fruits, tomatoes and nuts can trigger gout, even though they are not high in purines, and this can make management tricky^{[29, 30]}.

Consuming dark berries has been shown to lower purine conversion into uric acid and further reduce inflammation^[31]. This is due to them containing flavonoids and anthocyanins, both of which are antioxidants that enhance the collagen content of tendons and cartilages surrounding affected joints^[11].

Studies have shown that diets high in vitamin C and that are low in acid-forming foods (such as fruits, vegetables, herbs and spices) are less likely to develop gout^[32].

Vitamin C and gout

Vitamin C protects against gout by lowering serum uric acid, and this is thought to be due to greater removal of uric acid through the kidneys^[32]. A broad range of research has been focused on vitamin C’s protective properties. Whilst some research did not produce statistically significant results, the research did see gout attacks, flare-ups and incidence reduce when vitamin C is increased^{[19, 30, 32]}. One particular study over 20 years followed 47,000 participants and observed gout was significantly reduced, managed and limited when vitamin C intake was 500-1,000mg per day: 6-12.5 times higher than the official recommended daily intake of 80mg^[33-36]. Studies have shown that higher amounts of vitamin C in the bloodstream can significantly help to increase the amount of uric acid that is expelled through urine^[37]. Because vitamin C is an antioxidant, it may also help to reduce inflammation^{[35, 38]}.

Gout and Huel

Oats and flaxseed contribute moderate levels of purines. However, laboratory tests of Huel v3.0 Powders and Black Edition have come back below the level of detection and Hot & Savoury at 0.05%. Huel Powder v3.0 has a very high vitamin C content (60mg per 100g, equating to 300mg per 2000kcal) which helps to protect the body from gout attacks by aiding the reduction of circulating uric acid. Huel Powder v3.0 also has a high omega-3 fatty acid content, which aids the reduction of inflammation. Furthermore, as obesity is increasingly becoming the recognised exacerbating factor for gout, a calorie-controlled, nutrient-rich diet is advantageous to reduce symptoms, flare-ups and occurrence. Huel Powder v3.0 has a clear advantage here (view the nutritional profiles of Huel Powders (v3.0) here).

For those who are particularly prone to recurrent gout attacks due to poor uric acid clearance, it would, however, be prudent to gradually introduce Huel Powder v3.0 into the diet to see how it’s tolerated. Indeed, those who are notably susceptible to the negative effects of purines on their gout should limit their intake of Huel Products.

Balancing the literature and research, looking at the levels of purines vs the vitamin C, phytonutrient, antioxidant and omega-3 content as well as the GI of Huel Powder v3.0, which has a low GI of 16^[39]) it is credible to conclude that a regular intake of Huel Powder v3.0 will not increase the risk of developing or exacerbating the symptoms of gout.

Table 1: Percentage of purines in commonly consumed foods^{[17, 18, 22, 28, 29, 37]}

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