Cross-Contact
(Cross-contamination)

A Guide for People with Alpha-gal Syndrome

Cross-Contact and Alpha-gal Syndrome (AGS)

Some people with alpha-gal syndrome (AGS) react to food contaminated by mammalian meat or other mammalian products (1). This group can include people who tolerate dairy and other moderate risk foods. Contributing factors to the risk posed by cross-contact (also called cross-contamination) include:

  • The heat stability of alpha-gal which, unlike protein allergens, is not denatured at normal cooking temperatures (2,3)
  • Unlike protein allergens, alpha-gal is incorporated into glycolipids, and mammalian fats are thought to be its primary source (4).
  • Fat from cooking meat can be aerosolized and dispersed by air, as has been demonstrated in several studies (5) and which anyone who has ever cooked meat can confirm.
  • Fat tends to cling tenaciously to surfaces and can be difficult to completely remove.

Common Sources of Cross-Contact at Home and When Eating Out

Some of the more common sources of alpha-gal contamination include:

  • Contaminated cutting and preparation surfaces
  • Contaminated knifes and other kitchen cutlery, when not cleaned between uses
  • Grills, pots, pans, spatulas, and other cooking utensils
    • Grills are a common  problem, and many people with AGS have two grills: one for cooking foods that contain alpha-gal and a separate grill for cooking other foods. In restaurants, avoid grilled foods unless they are cooked on a grill that is not used for cooking mammalian meat.
    • Pots, pans, spatulas, and other cooking utensils used in the preparation and cooking of mammalian meats and other mammalian products need to be thoroughly cleaned before being reused or they can be contaminated with mammalian fat.
    • Wooden, plastic, and heavily-scratched cooking utensils can trap fat even when cleaned and may need to be replaced (6).
    • Cast-iron pans may need to be scrubbed and re-seasoned (6)
  • Droplets of fat from splatter or airborne droplets from cooking meat
  • Sponges used to clean items contaminated with mammalian meat and other mammalian products
  • Improper storage of food in refrigerators
    • Store mammalian meat on the bottom shelf or in a separate refrigerator drawer.
  • Ovens and microwaves contaminated with mammalian grease

Additional Sources of Cross-Contact at Markets and in Restaurants and Manufacturing Facilities

Additional sources of contamination at markets and in restaurants and manufacturing facilities include:

  • Fry oil
    • Sometimes mammalian fat is added to fry oil for flavor, but even when it’s not, oil used to fry mammalian meats or other mammalian products may be contaminated with alpha-gal.
  • Meat grinders and sausage making equipment
    • Ground poultry and poultry sausages are frequently contaminated with other meats.
  • Deli meat slicers
    • Sliced turkey and cheese (for those who tolerate it) can be contaminated when sliced on slicers that are also used to slice mammalian meat.
  • Butchers and meat departments
    • Cross-contact can occur during handling
  • Gloves, if not changed after handling mammalian products
  • Shared processing lines/facilities

Resources

Find more information about cross-contact and how to avoid it on the FARE Avoiding Cross-Contact page.

Darcie Clements’ article “Reducing Environmental Alpha-gal Exposure” explains how to reduce your exposure to alpha-gal from cross-contact and other environmental sources.

References

1. Commins SP. Diagnosis & management of alpha-gal syndrome: lessons from 2,500 patients. Expert Review of Clinical Immunology. 2020 Jul 2;16(7):667-77.

2. Hilger C, Fischer J, Swiontek K, Hentges F, Lehners C, Eberlein B, Morisset M, Biedermann T, Ollert M. Two galactose‐α‐1, 3‐galactose carrying peptidases from pork kidney mediate anaphylactogenic responses in delayed meat allergy. Allergy. 2016 May;71(5):711-9.

3. Apostolovic D, Tran TA, Hamsten C, Starkhammar M, Cirkovic Velickovic T, van Hage M. Immunoproteomics of processed beef proteins reveal novel galactose‐α‐1, 3‐galactose‐containing allergens. Allergy. 2014 Oct;69(10):1308-15.

4. Wilson JM, Platts-Mills TA. The oligosaccharide galactose-α-1, 3-galactose and the α-Gal syndrome: insights from an epitope that is causal in immunoglobulin E-mediated immediate and delayed anaphylaxis. Eur Med J. 2018;3:89-98.

5. Poudel BK, Choi J, Park JH, Doh KO, Byeon JH. In vitro exposure of simulated meat-cooking fumes to assess adverse biological effects. Scientific reports. 2017 Sep 7;7(1):1-9.

6. Clements, D. Adapting to AGS Part 1: Understanding Tolerance Levels. Alpha-gal Syndrome blog. 2018 Jan.

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