Ask Tufts Experts: January 2023

Elimination diets … Fish oil and heart arrythmia


Q: What is an elimination diet? Can it be used for weight loss? 

A: Alicia Romano, MS, RD, CSNC, a registered dietitian/nutritionist with the Frances Stern Nutrition Center who specializes in gastrointestinal diseases and food allergies, answers: “I’m glad you asked this question! Elimination diets are sometimes used as diagnostic or treatment tools. They are not for weight loss.

“For several important reasons, elimination diets should be conducted under the guidance of an experienced medical professional (like a doctor or registered dietitian). First, long-term elimination of a wide range of foods from your diet can lead to inadequate nutrient intake, so guidance is essential to ensure you stay healthy. An expert will also point out where to find hidden ingredients, additives, or food components that could be triggering your symptoms.

“In general, there are three main steps in an elimination diet:

1. Remove all traces of the suspected problem food(s) for a period of time and see if symptoms resolve. The health-care professional will ask you to keep a record of all food intake and symptoms.

2. Add foods back one at a time and watch for a return of symptoms.

3. Adjust your dietary intake to cut back on or eliminate problem foods or food components as necessary, while maintaining adequate nutrient intake.

“The duration of elimination varies considerably based on the root cause, as do the required dietary modifications. For example, someone who may be sensitive to a high FODMAP foods (like wheat and foods containing lactose and fructose) may only need to reduce intake or avoid foods for a short time with the potential to add them back in. Those with food sensitivities may also find there is a threshold at which they can tolerate a certain food. Food allergies are different and should be diagnosed under the supervision of a physician.

“There are many elimination-style diets out there that lack standard protocols. Assuming a food intolerance or sensitivity is the culprit for one’s health issues can perpetuate an unhealthy relationship with food, so I strongly advise people not to self-diagnose, and to seek professional help.”

Image © LeventKonuk | Getty Images
Some studies have associated fish oil supplement intake with increased risk for heart arrhythmia.

Q: I recently heard that fish oil supplements can cause the heart problem AFib. Is this true? Should I stop taking them?

A: Dariush Mozaffarian, MD, DrPH, a cardiologist, dean for policy at the Friedman School, and Tufts Health & Nutrition Letter editor-in-chief, answers: “Some clinical trials have suggested omega-3 fatty acid supplements (like fish oil) may be associated with an increased risk for atrial fibrillation (AFib), a common heart rhythm disorder that increases stroke risk. In an analysis of five randomized controlled trials, omega-3 fatty acid supplementation in doses ranging from one to four grams per day was associated with a significantly increased risk for AFib compared to people who did not take the supplements. Participants in these studies had elevated blood triglyceride levels and either had cardiovascular disease or were at high risk.”

“On the other hand, observational studies generally suggest that regular consumption of fish is associated with lower risk of AFib. It is also important to note that at least some of the trials in the review mentioned above also showed that omega-3 supplements reduced risk of heart attacks, strokes, and deaths.

“Talk to your health-care provider about risks versus benefits if you currently take fish oil supplements or plan to start.”



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