Lauren Williams had a problem. The registered dietitian nutritionists at Cook Children’s Health Care System in Fort Worth, Texas had a few patients with the rare condition familial chylomicronemia syndrome, which in the absence of an approved therapy, is treated by diet.
FCS results from a genetic mutation that prevents people with the condition from being able to metabolize long-chain fatty acids. The consequence of this is that people with the condition can develop high triglyceride levels and suffer stomach pain, fatigue, brain fog, and potentially life-threatening bouts of pancreatitis.
The condition is difficult to diagnose. It is thought to afflict one in 1 million people, but people can suffer from the symptoms without ever getting a diagnosis. Though there are drugs in development, the only way to treat someone with the condition today is through a restrictive diet.
But here’s the problem. Even if a patient is diagnosed, no one ever bothered to draw up agreed upon dietary guidelines for people with the condition. “Whenever I did research, I came up at a loss,” said Williams. “At the time there wasn’t much information about FCS in general.”
Now, thanks to Williams and her colleagues, that’s changing. In a recently published article in the Journal of Clinical Lipidology, Williams and other experts constructed dietary guidelines based on existing evidence-based science for people with FCS.
Having such guidelines available to FCS patients matters for a number of reasons. The first is that like other rare disease patients, FCS patients may receive care from a variety of providers. “It’s helpful if everyone can be on the same page,” Williams said.
The other issue, though, is that eating a low-fat diet, as is prescribed for people with FCS, may not be as obvious as it seems. It is highly restrictive—people with FCS should limit their fat intake to less than 15 to 20 grams per day—about 10 to 15 percent of their daily caloric intake.
But the solution is not just adhering to a protein-rich diet because, as the article illustrates, meats and nuts contain fat. Also, such things such as alcohol and simple carbohydrates can be problematic too. Excess calories from simple carbohydrates and sugar are metabolized into fat. And alcohol is known to raise triglyceride levels as well. Even vanilla extract can be problematic because it contains alcohol.
There are fats that are available that can be safely used by FCS patients known as MCTs, or medium-chain triglycerides. These fats are metabolized differently than LCTs. However, while they can be found in grocery stores, Williams advises that FCS patients should only use pharmaceutical grade MCTs because oils sold in grocery stores may lack the necessary purity and be mixed with other long-chain triglycerides, or LCTs. MCTs may work for a salad dressing, but they burn at too low a temperature to be used for cooking.
Though it may be easy to prescribe such a restrictive diet, Williams is sensitive to the reality that FCS patients face and the fact that the diet can affect their overall quality of life, as well as their psycho-social wellbeing.
Because of that, she said it’s important for these patients to connect with other FCS patients (The FCS Foundation is one place to start). In addition to getting support, fellow patients can provide recipes, cooking tips, and kitchen gadgets that may be helpful for living with a low-fat lifestyle and adhering to the diet.
“It is a very difficult diet to follow, but it’s not impossible,” said Williams. “It’s important to not only have a medical team, but to connect your patient with the FCS community as well. Connecting with others that have FCS helps with lots of things.”
July 9, 2018
Lauren Williams, clinical dietician at Cook Children’s Health Care System