Storage Protein Allergies (2S Albumin, 7S Globulin): Using Biomarkers to Predict Severe Nut Reactions
For anyone living with a suspected or confirmed nut allergy in the UK, understanding the difference between a mild reaction and a potentially severe one is a significant concern. Storage protein allergy biomarkers — specifically 2S Albumin and 7S Globulin — are helping to bring greater clarity to that question. Through targeted blood testing, it is now possible to identify which specific proteins within nuts an individual's immune system is responding to, offering a more detailed picture of risk than a standard allergy panel alone.
This educational guide explains what these biomarkers are, how they differ, what results may suggest, and who might benefit from this type of component-resolved allergy testing.
What Are Storage Protein Allergies? A Clear Definition
Storage protein allergies refer to immune responses triggered by specific structural proteins found within nuts and seeds. Unlike minor surface proteins, storage proteins are deeply embedded within the food matrix, making them heat-stable and resistant to digestion. This stability means they can provoke immune reactions even after a food has been cooked or processed.
The two most clinically significant storage protein groups in nut allergy assessment are:
- 2S Albumins – compact, highly stable proteins associated with a higher likelihood of systemic allergic reactions
- 7S Globulins – larger seed storage proteins linked to moderate-to-severe allergic responses
These proteins survive gastric acid and digestive enzymes, which means sensitisation to them may carry a higher risk of reaction severity compared to sensitisation to proteins that break down during digestion.
Practical Insight: A standard total IgE or broad nut allergy test tells you that a reaction may be occurring. Storage protein component testing can begin to suggest what kind of reaction and how severe it might be.
2S Albumin vs 7S Globulin: Understanding the Difference
| Feature | 2S Albumin | 7S Globulin |
|---|---|---|
| Stability | Highly heat and acid stable | Moderately stable |
| Common Sources | Peanut (Ara h 2, Ara h 6), Sesame (Ses i 1), Brazil nut (Ber e 1) | Peanut (Ara h 1), Walnut (Jug r 2), Cashew (Ana o 1) |
| Associated Risk | Higher likelihood of systemic reaction | Moderate-to-severe reaction risk |
| Digestion Resistance | High | Moderate |
| Clinical Relevance | Often found in those with more pronounced reactions | Associated with broad multi-nut sensitisation |
| Example Biomarkers | Ara h 2, Ara h 6, Ses i 1 | Ara h 1, Jug r 2, Ana o 1 |
Sensitisation to Ara h 2 (a 2S Albumin found in peanuts) in particular has been widely studied within European allergy research and is considered one of the more clinically significant biomarkers when assessing peanut allergy severity risk.
Practical Insight: Not all nut-reactive individuals will have raised storage protein antibodies. Some may have sensitisation only to PR-10 proteins (such as Ara h 8), which are far less stable and more often linked to mild, localised reactions — particularly in those with birch pollen allergy.
Why Standard Allergy Testing May Not Be Enough
A total IgE test or a broad multi-allergen panel can confirm that an immune response to nuts is present. However, it cannot reliably differentiate between sensitisation that carries a higher risk of systemic reaction and sensitisation that is more likely to result in minor oral symptoms.
This distinction matters considerably. Two individuals may both return a positive peanut IgE result, yet one may be sensitised primarily to Ara h 8 (a birch-related protein, typically associated with mild oral allergy syndrome) while the other is sensitised to Ara h 2 (a 2S Albumin associated with more significant systemic responses).
Component-resolved diagnostics (CRD) uses individual biomarker testing to identify precisely which proteins within a food are triggering an IgE response. This level of detail is not available from whole-allergen extract testing alone.
Explore our full range of allergy blood testing options to understand what types of panels are available at our nurse-led clinic.
Who May Benefit from Storage Protein Biomarker Testing?
This type of specific component testing may be worth considering for individuals who:
- Have received a positive result on a standard nut allergy panel and want more detail about which proteins are involved
- Experience variable reactions to nuts and want a clearer picture of their immune profile
- Have a personal or family history of nut-related reactions and are seeking a baseline assessment
- Are managing a known nut sensitivity and wish to understand whether their immune reactivity profile has changed over time
- Are based in London or elsewhere in the UK and have limited access to detailed allergy assessment through NHS pathways
In a busy urban environment like London — where eating out, international cuisine, and processed foods are all part of daily life — having detailed biomarker information can support more informed lifestyle decisions around food choices and avoidance.
Practical Insight: This testing does not replace professional allergy assessment, but it does provide a detailed, measurable data point that individuals can discuss with an appropriate healthcare professional.
If you are unsure which panel is most suitable, our allergy testing guide provides educational support on choosing the right test for your situation.
How Often Should Storage Protein Testing Be Considered?
There is no universal fixed interval for repeat component-resolved allergy testing. However, the following general considerations may apply:
- Initial assessment – A baseline panel can help establish a starting profile for those with known or suspected nut sensitivity
- Periodic review – Some individuals choose to repeat testing every 12–24 months to monitor any changes in their IgE reactivity profile over time
- Following a significant change in health, diet, or reaction history – A repeat test may offer updated data to discuss with a healthcare professional
Testing frequency should always be guided by individual circumstances and discussed with an appropriate healthcare professional rather than followed as a fixed schedule.
What Might Results Suggest? Understanding Your Biomarker Profile
Results from storage protein testing are reported as specific IgE levels measured in kUA/L. These numerical values are used to indicate the degree of immune sensitisation to a particular protein component. It is important to note that:
- A higher specific IgE value to a storage protein such as Ara h 2 or Ses i 1 may suggest a greater degree of sensitisation to that protein
- A positive result does not confirm that a reaction of any particular severity will occur — it indicates immunological sensitisation
- A negative result to storage proteins with a positive result to other components can suggest that the reaction profile may be associated with lower-risk proteins
Results are best interpreted in the context of an individual's reaction history and overall clinical picture, ideally discussed with an appropriate healthcare professional or allergy service.
For a broader overview of how specific IgE levels are interpreted, visit our understanding allergy test results resource.
Nut Allergy Testing in London: Access and Awareness
London has one of the most diverse food cultures in the world, making nut allergy awareness especially relevant for residents. Cross-contamination risks in restaurant settings, hidden allergens in international food products, and the prevalence of tree nuts in cuisines from South Asia, the Middle East, and the Mediterranean are all daily considerations for those with nut sensitivities.
Despite this, NHS allergy services in the UK remain under significant demand, with waiting times for allergy assessment varying considerably by region. Private nurse-led clinics offering component allergy blood testing provide an accessible route for individuals who wish to obtain biomarker data without long delays.
At Allergy Clinic, our nurse-led team provides allergy blood testing and detailed written reports. We do not offer prescriptions, medical treatment, or specialist clinical management — but we do provide clear, actionable testing data that individuals can use in conversation with their healthcare team.
FAQ: Storage Protein Allergies and Biomarker Testing
1. What is a storage protein allergy?
A storage protein allergy is an immune response to stable, digestion-resistant proteins found within nuts and seeds. These proteins — including 2S Albumins and 7S Globulins — are embedded within the seed structure and may be associated with more significant immune reactions compared to surface or PR-10 proteins.
2. What is the difference between 2S Albumin and 7S Globulin in allergy testing?
2S Albumins such as Ara h 2 are highly compact and heat-stable, and sensitisation to them is considered particularly clinically relevant. 7S Globulins such as Ara h 1 are larger proteins associated with moderate-to-severe sensitisation profiles. Both are measured through specific IgE component blood testing.
3. Can a storage protein blood test tell me how severe my nut allergy is?
It can provide a more detailed picture of which proteins you are sensitised to, which may indicate a higher or lower risk profile. However, no blood test can definitively predict the severity of a future reaction. Results should always be discussed with a healthcare professional.
4. Is storage protein allergy testing available on the NHS?
Component-resolved diagnostics are available through some NHS allergy centres, though access varies significantly by region. Many individuals in the UK choose private nurse-led testing to access this level of detail more promptly.
5. Which nuts are associated with 2S Albumin biomarkers?
Peanuts (Ara h 2, Ara h 6), Brazil nuts (Ber e 1), and sesame (Ses i 1) are among the most studied sources of 2S Albumin proteins. These biomarkers can be measured individually through specific IgE blood panels.
6. Do I need a GP referral to book storage protein allergy testing?
At our nurse-led clinic, you do not require a GP referral to book a blood test. We provide testing and written results reports, which you can then share with your GP or healthcare provider.
7. Is a positive Ara h 2 result always serious?
A positive Ara h 2 result may suggest sensitisation to a clinically significant peanut storage protein. However, result interpretation always requires individual clinical context. Sensitisation does not automatically confirm a particular reaction pattern and should be discussed with a qualified healthcare professional.
8. Can storage protein testing help with multi-nut sensitisation?
Yes. Component panels can test multiple nut and seed proteins simultaneously, helping to identify whether an individual is sensitised to proteins across different nut species — for example, walnut (Jug r 2) alongside peanut (Ara h 2) — which may support a more detailed understanding of their sensitivity profile.
9. How is a storage protein allergy test performed?
Testing involves a standard blood draw from a vein, with results typically returned within a few days. At our nurse-led clinic, all samples are taken by trained nurses and sent to an accredited laboratory for analysis.
10. Where can I book a storage protein allergy blood test in London?
You can book directly through Allergy Clinic without a referral. Our nurse-led service provides testing and detailed written reports from our London-based clinic.
Taking a Proactive Approach to Allergy Awareness
Understanding your allergy biomarker profile — including storage proteins such as 2S Albumins and 7S Globulins — is one of the most informed steps you can take if you are concerned about nut sensitivity. Detailed component-resolved testing offers a level of insight that a standard panel cannot match, helping to build a clearer picture that you can explore further with a healthcare professional.
If you are based in London or anywhere in the UK and would like to access nurse-led allergy blood testing in a comfortable, professional setting, we welcome you to explore the services available at Allergy Clinic.
EEAT Authority Statement
This article has been prepared by the Allergy Clinic editorial team in accordance with UK medical editorial standards. All content is grounded in established immunological principles relating to component-resolved diagnostics and IgE-mediated allergy. Clinical terminology reflects current European allergy research and UK public health communication standards.
This content has been reviewed for compliance with GMC advertising guidance, CQC patient communication standards, and ASA guidelines governing health-related editorial content.
Disclaimer
This article is intended for educational and informational purposes only. The content does not constitute medical advice, diagnosis, or treatment, and should not be used as a substitute for professional medical assessment. Individual symptoms, health concerns, or blood test results should always be evaluated by an appropriately qualified healthcare professional. Allergy Clinic is a nurse-led testing and screening service; we do not offer medical treatment, prescriptions, or specialist clinical management. No outcomes are guaranteed from any screening or testing service. If you experience a severe allergic reaction or acute symptoms, please seek urgent medical care immediately.
