What is a low-histamine diet?
Histamine is not just about allergy. Nutritionist Kerry Torrens explores what histamine is, why it’s important for health, and what problems may arise if you have too much of it.
What is histamine?
Histamine is a chemical typically associated with allergy, but it has other important functions in the body, including communicating with the brain, triggering the release of stomach acid, and dilating blood vessels to lower blood pressure. We all need histamine, especially when we graze a knee or suffer a bee sting. Histamine is found throughout the body, and is mainly stored in immune cells called mast cells and basophils. It performs its role by attaching to specific receptor cells at key locations.
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When is histamine a problem?
When levels get too high or we can’t break it down properly, histamine can start to affect normal bodily functions. This can lead to allergy-like symptoms, including itching, sneezing, headaches, joint pain, irritable bowel and nausea. You may not experience all of these symptoms, all of the time but with an accumulation of histamine you may find symptoms worsening. Studies suggest the condition is more common in women, especially those at mid-life. Anti-histamine drugs and certain supplements may be used to block histamine activity and relieve some of the symptoms. Sadly, the condition which is often referred to as 'histamine intolerance' has a number of underlying mechanisms, and no reliable test for diagnosis.
How does histamine build up in the body?
Our mast cells release histamine in response to certain triggers, and we get some histamine from the foods we eat. Our diet plays a key role, because some foods contain histamine, some foods are thought to promote the release of histamine (known as histamine liberators), and some foods do both. An example is alcohol – it contains histamine and encourages our bodies to release histamine.
The body breaks down histamine using certain enzymes, with the Diamine Oxidase (DAO) enzyme being responsible for dealing with the foods we eat. How efficient this enzyme is depends on our genetics, diet and the health of our gut. It can also be affected by painkillers, anti-depressants and other medication. For women, oestrogen levels may influence the amount of histamine circulating in the body, and in turn may make the break down enzyme, DAO, less effective.
Why is assessment so difficult?
Histamine intolerance is unlike other allergies or sensitivities, in that it is not a reaction to the histamine itself, but to the fact that we’ve too much of it. This can make recognising and managing the condition very difficult. Whether you experience symptoms or not will also depend on whether your personal tolerance level has been breached. Often referred to as your histamine ‘bucket’, once this capacity is met and exceeded, your bucket starts to overflow and your symptoms become more challenging.
There are numerous factors that will influence how full your histamine ‘bucket’ might be. These include genetics, medication, diet, time of year, nutritional deficiencies, stress levels, hormones, gut health and your environment, including whether you suffer from environmental allergies like pollen, dust mites etc.
Histamine intolerance has many underlying mechanisms and to complicate matters further, levels of histamine in foods will vary dependent on age, storage time and processing. This means histamine levels can differ even for the same food or product. Generally speaking, fresh, 'young' foods tend to have less histamine, while aged and fermented foods have more. This means even some healthy foods, like kefir, yogurt and sauerkraut, may be problematic to those with a histamine intolerance.
How to manage histamine levels?
One of the most useful tools in assessing whether histamine intolerance is relevant for you and to understand your personal threshold is to follow a low-histamine diet. It’s important to emphasise that this is not a long-term treatment option, because following such a restrictive diet is unlikely to be nutritionally adequate. You will need to work with a registered dietician to remove foods that are high in histamine or histamine-releasing. Using a food diary, you will be advised to record your reaction to foods as you slowly reintroduce them, while carefully assessing tolerance levels and considering other relevant factors. Guided by your dietician and following this initial assessment, you will be able to establish a long-term eating plan that is balanced and suitable for your needs.
To help get you started, here are some common foods and their likely histamine effects. You should be aware that histamine levels may vary, so this is given for guidance only:
Keeping a food diary is an important component of this approach, because it helps you identify problem foods and pinpoint preparation and cooking methods that may need to be adapted. Keeping a diary can be quite revealing and might suggest some foods, even those usually considered healthy, may be a problem.
In the first instance, when aiming to reduce symptoms, eliminating alcohol, dairy and fermented foods may be helpful, because these foods contain histamine and some promote the release of histamine. Other foods block the activity of the DAO enzyme and as such should also be avoided, including caffeinated drinks.
Foods that promote the release of histamine and are known as histamine liberators, include:
- Tomatoes, avocado and Brussels sprouts
- Pulses and legumes, including peanuts
- Bananas, strawberries, pineapple, papaya, citrus and kiwi
- Seafood and shellfish
- Cocoa and chocolate
Some nutrients and plant compounds act as natural antihistamines, inhibiting the build-up of histamine in the body. These include vitamins C and D, quercetin and curcumin. Including foods that are rich sources of these may be helpful. Other nutrients support the activity of the DAO enzyme, including the B vitamins, such B6, and minerals such as copper, zinc and manganese.
Some examples of foods that act as natural antihistamines include:
- Watercress and onions
- Apples and blueberries
- Fresh herbs, including tarragon, thyme and chamomile
- Fresh ginger, galangal and turmeric
What can I do today?
Buy and cook from fresh – aim to shop little and often, because the fresher your food, the less histamine it is likely to contain. Cooking from fresh rather than using leftovers or prepared foods may also prove beneficial. It is better to freeze leftovers for use another day rather than storing them in the fridge. Meal composition and the time between your meals may also affect your symptoms.
Look at your lifestyle – for example, if environmental allergens are relevant for you, minimise your exposure. Aim to manage stress levels, and explore which forms and levels of exercise are beneficial for you, because this can vary. If you're experiencing a hormonal shift, for example puberty or peri-menopause, and are experiencing symptoms suggestive of a histamine intolerance, check with your GP for guidance.
If you are considering attempting any form of change to your normal eating plan, please consult your GP first to ensure you can do so without risk to health.
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This article was published on 24 July 2020.
Kerry Torrens BSc. (Hons) PgCert MBANT is a Registered Nutritionist with a post graduate diploma in Personalised Nutrition & Nutritional Therapy. She is a member of the British Association for Nutrition and Lifestyle Medicine (BANT) and a member of the Guild of Food Writers. Over the last 15 years she has been a contributing author to a number of nutritional and cookery publications including BBC Good Food.
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