Increased Protein Digestion Reduces Food Intolerances

Food intake, considered a pleasure by most, also represents a health hazard in situations where metabolism is altered or if food proteins are recognized as harmful by the immune system. In the latter case, IgG, IgE and IgA antibodies are produced by the immune system in response to the food “attack”.  The number of food-allergic patients is increasing, as is the severity of the reactions. The effects range from mild rashes, diarrhea, and/or migraine headaches to all-out systemic dysfunction.

One of the functions of the digestive tract is to change food into a substance that won’t trigger the immune system to launch an attack.

Several methods are used in the body to accomplish this task.   Stomach acid denatures food proteins.  Denaturation removes the “glue” holding the structure of the food protein together and often results in loss of any function associated with the protein.

However, even denatured proteins can be allergenic.   The next and most definitive step for rendering food proteins harmless is enzymatic degradation that begins in the stomach but predominates in the small intestine.  Denaturation actually sets up the protein for optimal break down by protease enzymes.

The immune system in the gut is triggered by a number of factors but size of the offending protein is the most predominant.  The larger the protein, the more likely it is to set off the alarm for IgG antibody production.  Conversely, smaller proteins or fragments are able to slip under the radar for immunity activation.  Research from several labs demonstrate that when protein digestion is compromised, antibody production to that food protein increases (1 – 3).

A compromised digestive system can occur easier than one may think.

The simple act of taking an antacid reduces the activity of pepsin, the major protease enzyme in the stomach, by raising the pH of the stomach over 5.0.  Many on H2-receptor blockers have increased food allergy symptoms because the resulting low stomach acid fails to activate the pepsin enzyme system.

Larger food protein fragments are then passed on to the intestinal tract and have the potential to become allergens (2 – 4).  Conversely, research indicates that pre-treatment of food proteins with protease enzymes results in a less allergenic potential (5 – 6).  Heating of a protein alone will not break down a food protein sufficiently, so cooking is no guarantee of allergy prevention.

The World Health Organization proposed in 2001 that food proteins be tested for the allergenic potential.  One of the parameters for consideration is the resistance to enzymatic digestion by some food proteins (7).  A positive association was found between resistance to digestion and development of food allergy.  Food proteins with a high content of proline amino acids, like gluten, are very difficult to digest by human digestive enzymes.

What does this mean for the consumer?  Obviously, increasing the digestion of food proteins decreases the chances of potential allergy development.  Unfortunately, our own digestive enzymes are not always sufficient.

By supplementing with additional acid-stable enzymes from fungal, microbial, or plant sources, we can increase the chance of food proteins being sufficiently degraded.

These “outside” sourced enzymes are compatible with our digestive systems but have additional properties that provide us with more thorough digestion.  The use of supplemental enzymes increases the bioavailability of food nutrients to our system, provides a healthier environment for the probiotic bacteria in our gut, and eliminates the unwelcome side effects of unhealthy digestion, such as fermentation, gas, and bloating.

Oral tolerance of food proteins is an important aspect of our digestive and immune system.  The use of over-the-counter enzyme supplements specifically formulated for protein digestion (such as AFP-Peptizyde from Houston Enzymes) may further increase digestion of food proteins. Broader spectrum enzyme products, such as TriEnza from Houston Enzymes, benefit not only protein digestion, but breakdown of carbohydrates, starches, and fats is also increased.


1. Anthoni S, Savilahti E, et al. Milk protein IgG and IgA: The association with milk-induced gastrointestinal symptoms in adults. World J Gastroenterol 2009; 15:4915-4918.

2. Schmidt DG, Meijer RJ, et al. Raising the pH of the pepsin-catalyzed hydrolysis of bovine whey proteins increases the antigenicity of the hydrolysates. Clin Exp Allergy 1995; 25(10):1007-17.

3. Untersmayr E, Scholl I, et al. Antacid medication inhibits digestion of dietary proteins and causes food allergy: a fish allergy model in BALB/c mice. J Allergy Clin Immunol 2003; 112(3):616-23.

4. Untersmayr E and Jensen-Jarolim, E. The role of protein digestibility and antacids on food allergy outcomes. J Allergy Clin Immunol 2008; 121(6):1301-10.

5. Kim SB, Ki KS, et al. Peptic and tryptic hydrolysis of native and heated whey protein to reduce its antigenicity. J Dairy Sci 2007; 90(9):4043-50.

6. Burks AW, Williams LW, et al. Allergenicity of peanut and soybean extracts altered by chemical or thermal denaturation in patients with atopic dermatitis and positive food challenges. J. Allergy Clin Immunol 1992; 90(6 Pt 1):889-97.

7. Bannon G, Fu T-J, et al. Protein digestibility and relevance to allergenicity. Environ Health Perspect 2003; 111:1122-24.

Note: These statements and/or products have not been evaluated by the FDA and are not meant to diagnose, cure, treat, or prevent any illness.