There’s something fishy about fish oil supplements.

Each time we interview a nutrition expert, we like to ask this question: What is the one item marketed to athletes that you absolutely will not eat, or that totally irritates you? We’re always surprised by the answers, like former professional Ironman athlete Brendan Brazier telling us chocolate milk gets his goat (milk). FN recently talked with Paleo diet expert Diane Sanfilippo, author of “Practical Paleo” and the “21 Day Sugar Detox.” Here’s what she could live without.

FN: There is a huge amount of money being made off of athletes and nutrition- gels, powders, chews. What is one item, food or product that you will absolutely not eat or that totally irritates you as a nutritionist?

DS: Fish oil.

FN: We didn’t see that one coming. Tell us why.

DS: Fish oil really irritates me because you should be getting fish oil from eating fish. My lunch today was a tin of BPA-free sardines with hot sauce and olive oil. Fish oil in and of itself—when it is in fish, from nature—is a great food; and it’s rich in Omega-3s, which are anti-inflammatory. I don’t think that people consider how fish oil supplements are made. Fish oil is a healthy thing to have in your diet, so yes, you should be eating it. But anytime you isolate nutrients from the food source, you don’t know how beneficial it will be, and you should get it in a whole food form so that you don’t risk overdosing on it. Fish oil is a poly-unsaturated fat, which is highly susceptible to oxidative damage. When produced, there is a risk for oxidation. Then people refrigerate them and you risk oxidation again. If people want something to supplement with, go with cod liver oil. It has some omega-3s and vitamins A and D. It’s made from a cold fermentation process, not a refining process. This cold fermentation process has been done historically as a way to preserve the nutrients in fish livers. People and athletes are looking for the shot in the arm to make them better, they have this mindset that more is better, and it’s not about eating a fish oil pill. Really the best way to go is to just eat fish a couple of times a week. One note- Diane Sanfilippo did mention that fermented cod liver oil tastes fairly bad, so look for a flavored one, such as cinnamon. She said the cinnamon smell is what is most helpful for covering up the taste, and smell, of the cod liver oil.

For more information on Paleo diet expert, Diane Sanfilippo, visit her website: balancedbites.com