seafood intolerance food

Shellfish Sensitivity and Intolerance

Fish and shellfish consumption has seen a steady rise in the past decade as more Americans add it to their diets. Whether it’s a shrimp scampi or a summer clambake, shellfish can be a great way to get Omega-3 and 6 fatty acids into your diet. But not everyone’s body reacts well to seafood. If you have an intolerance or sensitivity (defined by YorkTest as a food-specific IgG reaction), eating these shellfish may actually be a problem food. Could your stomach cramps actually be a sign of shellfish sensitivity?

What causes shellfish intolerance?

A shellfish intolerance occurs when your digestive system does not have the appropriate enzymes to break down shellfish protein, producing an inflammatory response and difficulty digesting. This is different from a shellfish food allergy which induces adverse reactions by the body’s immune system. These reactions tend to be more serious and could be life threatening especially if they cause an anaphylactic reaction affecting the respiratory system.

Whilst you need to actually eat shellfish to experience intolerance symptoms, with a shellfish allergy you can experience symptoms from just touching or cooking shellfish depending on  the severity of the food allergy.

It’s also important to note that one off digestive reactions to shellfish could also stem from food poisoning rather than a food intolerance if the shellfish is appropriately prepared or not fresh. It is for this reason that it’s a good idea to keep a food diary to monitor offending foods.

Signs of shellfish intolerance

Shellfish sensitivity intolerance can appear up to 72 hours after eating shellfish and can range from mild symptoms to hypersensitive reactions. If you are suffering from a seafood or shellfish intolerance, it is important to discover which particular seafood is the offending food.

Digestive symptoms of shellfish sensitivity may include:

  • Abdominal pain
  • Bloating
  • Nausea
  • Vomiting
  • Diarrhea

Premium Food Sensitivity Test


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The Premium Food Sensitivity Test measures your IgG reactivity to 200 foods and drinks. Get answers on which foods could be triggering your IBS symptoms, headaches, bloating, tiredness, and more.  Simply collect your finger-prick blood sample at home. Mail it to our laboratory for testing. Then receive your results online within 7 days!

  • 200 ingredients tested
  • Tests are HSA and FSA accepted
  • Analyzed in our accredited laboratory
  • Clear, color-coded results show your IgG reactivity score for each ingredient

Customers must be aged 18 years or over to take this test. For under 18s, take our
Junior Food Sensitivity Test. This test is not available to customers who are pregnant or breastfeeding.

Testing for Shellfish Sensitivity

In order to find out whether your symptoms are indeed tied to a shellfish sensitivity, we recommend taking a food sensitivity test to determine whether a sensitivity to shellfish is to blame and whether there are other ingredients that are also affecting you at meal times. At YorkTest, we analyze your IgG antibodies 1-4 through a finger prick blood sample, one of the most accurate methods of testing available. 

The blood test looks at over 200 ingredients to which you may have food sensitivities and their severity in an easy-to-understand traffic light system. Once you have your results, our team can help guide you to understand your food sensitivities, as well as advise you on your food and wellness journey.

seafood intolerance

Where to Look for Shellfish

Although there are easy ways to avoid eating shellfish, it’s still very important to read through food labels to fully avoid any accidental seafood consumption.

Make sure to familiarize yourself with the various types of seafood and shellfish below if you have a shellfish sensitivity:

  • White fish: Examples include cod, plaice, sole, coley, haddock, pollock, monkfish
  • Oily fish: Mackerel, tuna, sardines, anchovies, salmon, pilchards, herring, trout
  • Mollusks: Clams, mussels, oysters, snails, scallops, squid, octopus
  • Crustaceans: Shrimp, Crab, Lobster, Crayfish
egg sensitivity

Food swaps when you have a shellfish sensitivity

The USDA recommends eating around 8 ounces a week of a variety of seafood as part of a balanced diet. As seafood and shellfish contain a range of good nutrients such as the omega-3 fatty acids, EPA and DHA which can be found most notably in oysters amongst other fish.

To make sure you don’t miss out on these nutrients, try including the following food swaps for a healthy diet:

  • Leafy greens such as spinach
  • Avocado
  • Walnuts, brazil nuts, hazelnuts and pecans
  • Olive oil and flaxseed oil
  • Eggs
  • Sesame butter, pumpkin seed butter
  • Tofu
  • Coconut oil


routine elimination diet

If you suspect you have an underlying food sensitivity to shellfish, a Premium Food Sensitivity Test  may help you gain back control of your health and relationship with food. With your test results in hand and in line with professional medical advice, you can find a successful diet that helps put your digestive system at ease. YorkTest’s nutritional therapists can also help you take out the guesswork and optimise your daily food choices.

Other Intolerances