Understanding Refsum Syndrome and Phytanic Acid
Refsum syndrome, also known as classic Refsum disease, is a rare autosomal recessive genetic disorder that affects the body's ability to metabolize phytanic acid, a branched-chain fatty acid. This deficiency is typically caused by mutations in the PHYH gene, which provides instructions for the enzyme phytanoyl-CoA hydroxylase. Without a functional enzyme, phytanic acid cannot be properly broken down and instead accumulates in the blood, tissues, nerves, and organs. This toxic buildup is responsible for the wide range of symptoms associated with the condition, including peripheral neuropathy, retinitis pigmentosa, ataxia, and hearing loss.
The human body does not produce phytanic acid internally in significant amounts; nearly all of it comes from dietary sources. Phytanic acid is a derivative of phytol, which is part of the chlorophyll found in plants. Ruminant animals, like cows and sheep, convert the chlorophyll from the plants they eat into phytanic acid, which is then stored in their fat and passed on to humans through meat and dairy consumption. This metabolic pathway is why dietary restriction is the most effective long-term treatment for controlling phytanic acid levels and mitigating symptoms.
The Low Phytanic Acid Diet: Core Principles
Adhering to a low phytanic acid diet is the cornerstone of managing Refsum syndrome. The goal is to reduce daily phytanic acid intake to less than 10 milligrams. Successfully managing this diet requires careful meal planning and awareness of the principles that prevent a rapid release of stored phytanic acid from the body's fat tissues.
Foods to Avoid or Restrict
Ruminant Meats: Products from grazing animals are a major source of phytanic acid. This includes beef, lamb, and goat.
Dairy Products: Dairy fat from ruminant animals is high in phytanic acid. Patients must avoid butter, cheese, full-cream milk, and yogurt unless a special low-phytanic-acid product is used.
Certain Fish: While not all fish are high in phytanic acid, specific fatty and oily fish should be avoided. This includes cod, salmon, and haddock.
Baked Goods with Animal Fats: Many baked goods, including cakes, cookies, and pastries, are made with butter and other animal fats and should be avoided.
Some Nuts and Oils: Some nuts and oils, such as flaxseed oil and fish oil, have been shown to contain higher levels of phytanic acid. It is generally recommended to avoid them unless testing has proven otherwise.
The Importance of a High-Calorie, High-Carbohydrate Diet
One of the most critical aspects of managing Refsum syndrome is maintaining a stable energy supply and avoiding rapid weight loss. When the body is deprived of calories, it begins to break down its fat stores for energy. Because phytanic acid is stored in the body's fat tissues, this process releases a flood of the toxic fatty acid into the bloodstream, exacerbating symptoms.
To prevent this, patients must maintain a consistently high carbohydrate intake (at least 200g per day) and eat regular meals and snacks. This provides a steady supply of glucose, preventing the body from metabolizing fat stores. Any planned weight loss or fasting for medical procedures must be closely supervised by a medical and dietetic team to manage phytanic acid levels safely.
Dietary Comparison: High vs. Low Phytanic Acid Foods
| High Phytanic Acid Foods (Avoid) | Low Phytanic Acid Foods (Permissible) |
|---|---|
| Beef, Lamb, Goat | Chicken, Turkey, Pork |
| Butter, Cheese, Full-Cream Milk | Plant-based milk (almond, soy), most margarine |
| Oily Fish (Salmon, Cod) | White Fish (e.g., Tilapia), Shellfish |
| Baked goods with dairy/animal fats | Baked goods with vegetable oil, fruit-based desserts |
| Some nuts, flaxseed oil, fish oil | Vegetable oils (olive, sunflower), most seeds |
| Rapid weight loss or fasting | Consistent meals, regular snacks, controlled weight management |
Safe and Recommended Foods
- Lean Proteins: Chicken, turkey, pork, and most shellfish are generally safe alternatives to ruminant meat.
- Plant-Based Options: Legumes, tofu, and other plant-based protein sources are encouraged.
- Carbohydrates: Starches like bread, pasta, potatoes, and rice are vital for energy supply.
- Fruits and Vegetables: Most fruits and vegetables are safe, though testing for phytanic acid content is ongoing for some.
- Vegetable Oils: These are important sources of essential fatty acids for those on a restricted diet.
Seeking Professional Guidance
Managing a restricted diet for a rare metabolic condition is challenging and requires expert help. It is essential for patients with Refsum syndrome to work closely with a medical team and a registered dietitian specializing in metabolic disorders. Regular monitoring of blood phytanic acid levels and other nutritional markers (e.g., vitamins D and B12) is necessary to ensure the diet is effective and does not lead to nutritional deficiencies.
Conclusion
For individuals with Refsum syndrome, the low phytanic acid diet is not merely a recommendation but a critical, lifelong treatment. By systematically eliminating high-phytanic acid foods and focusing on a consistent, high-carbohydrate intake, patients can effectively manage their symptoms and improve their prognosis. Avoiding rapid weight loss and seeking continuous guidance from healthcare professionals are also vital components of successful management. For more information, the National Organization for Rare Disorders (NORD) provides resources and support: Refsum Disease - Symptoms, Causes, Treatment | NORD.
