A Tolerance Kitchen article.
The below content has been created with the input of a range of dietitians and sources. Following a low histamine diet should always be done alongside a qualified dietitian. Your own unique intolerances may make you more susceptible to certain foods than others, and long term adherence can lead to deficiencies in other important nutrients. You can find a list of trusted histamine dietitians here, all of whom offer 1:1 online sessions to help you get started and work with you to create a personalised diet.
Shopping With Confidence At The Fish Counter
The fish counter at a supermarket, or even better at your dedicated local fishmonger, should represent healthy, delicious meal options. That can quickly turn into a source of anxiety however when you're managing a histamine intolerance. You know that fish is a fantastic source of nutrients, particularly omega-3 fatty acids, but you have also learned it can be a significant source of histamine.
The good news is that, much like your local butcher, a good fishmonger can be one of your greatest allies. The key to successfully navigating fish and seafood is understanding one simple principle: freshness is everything. This guide is designed to arm you with the knowledge and the exact questions to ask, turning a potentially stressful trip into an empowering one.
Why Freshness is the Only Thing That Matters
Unlike some foods that are naturally high in histamine, freshly caught fish contains virtually none. Like the old expression goes, the problem literally begins the moment you take the 'fish out of water'. Bacteria on the fish's skin and in its gut start to convert an amino acid called histidine, which is naturally present in the fish's flesh, into histamine. The longer the fish sits, the more this conversion happens, and the higher the histamine level becomes.
This is why aged, cured, smoked, and tinned fish are almost always on high-histamine food lists. The time involved in their processing allows for significant histamine development. When you buy from a fish counter, your goal is to get that fish as close to its 'just-caught' state as possible, minimising the amount of histamine that ends up in your Histamine Bucket.
Your Script for the Fish Counter
Having a few clear, simple questions ready can make all the difference. It shows the person behind the counter that you know what you are looking for and helps them to help you. Here are four key questions to have in your toolkit.
1. "What came in fresh today?"
Polite and direct, this is the perfect opening question. Most fishmongers are passionate about their produce and will be happy to point you towards the very best of that day’s catch. It immediately narrows down your options to the freshest fish, saving you from having to guess.
2. "Has this been previously frozen?"
You will often see fish on ice at the counter that was delivered frozen and has been thawed for display. While this is a common practice, it is important information for you. Once thawed, the clock on histamine production starts ticking again. If a fish has been previously frozen, you need to treat it as having a very short shelf life and cook it that same day. This leads to the next, very important, question.
3. "Do you have any fish that was frozen at sea?"
For many people managing histamine intolerance, 'frozen-at-sea' (also known as individually quick frozen, and often displayed on supermarket packaging as IQF), which is the gold standard. This means the fish was caught, processed, and flash-frozen on the boat within hours. As we explore in our guide to freezing and histamine, this process acts as a pause button, stopping histamine development in its tracks. Buying fish that is still frozen solid, which you can find either at the counter or in the freezer aisles, is often the safest and most reliable option. You control the thawing process at home, just before you cook.
4. "Could I have a piece from the whole fish at the back?"
If you can tolerate a little bit of histamine and have chosen a fresh, never-frozen fish, this is a great final step. The pre-cut fillets at the front of the display have more surface area exposed to air and have been sitting out for longer. Politely asking for a new fillet to be cut from a whole fish at the back of the display ensures you are getting the freshest possible piece.
Remember that while awareness of histamine intolerance is low, it is not something that you should be ashamed of. Never feel like you are being difficult or picky by asking questions that will help you better manage your diet. Building up a relationship with your local fishmonger will help you feel more at ease over time, especially as your confidence levels grow.
When You Get Your Fish Home
Once you have your beautifully fresh fish, you still need to act quickly so as not to undo your hard work. Histamine will continue to develop as long as the fish is fresh (not frozen).
- Cook it today: The best plan is to cook and eat your fresh fish on the day you buy it. Do not let it sit in the fridge overnight
- Freeze it immediately: If your plans change or you have bought extra, portion it up and put it straight into the freezer. Remember, you can freeze fresh fish, but you should never refreeze fish that was previously frozen and then thawed
- Be careful with leftovers: As with all foods, leftover fish will be higher in histamine than the original meal. It is often best to cook only what you need
A Note on Oily Fish and Shellfish
Some types of seafood require extra caution. You can find a more detailed breakdown in our complete guide to fish and seafood, but here are the key points:
- Oily Fish: Species like tuna, mackerel, and sardines are naturally higher in the amino acid histidine. This means they have the potential to create histamine more quickly and in greater amounts than white fish. For these, absolute freshness is non-negotiable
- Shellfish: Prawns, mussels, and other shellfish spoil extremely quickly. The safest way to buy them is often frozen (ideally raw and frozen) and to cook them directly from frozen or immediately after thawing
Your journey with histamine intolerance is personal, and finding what works for you is a process of discovery. For those with a diagnosed DAO deficiency, managing dietary histamine is a key part of the puzzle. For some, this may include supporting their body's ability to digest external histamine. It is possible to make up for a lack of natural DAO by taking DAO supplements, such as our Aperitif, which are designed to be taken prior to ingesting histamine-rich food or drink.
By approaching the fish counter with a little knowledge and a few simple questions, you can feel confident in your choices and continue to enjoy the many benefits of including fresh fish in your diet. As always, we recommend discussing any significant dietary changes with a registered dietitian or qualified healthcare professional.
This article is for informational purposes only and does not constitute medical advice. Please consult a qualified healthcare professional for advice specific to your situation.