Peanut butter is a food that should not be lacking in the pantry of every home in the United States of America and certain European nations. It possesses a high mixed caloric value, that is lipidic and glucidic, deriving both from the nature of the seed itself and from the sugary (sucrose) and oily (palm oil) component introduced during the manufacturing process. It is also an excellent source of protein (average content 25g/100g), so much so that in the nineteenth century it was commonly called “the meat of the poor”. Its mineral content such as zinc, copper, calcium, magnesium, potassium is remarkable, without considering that of phosphorus (mainly as phospholipids). Among the most represented vitamins are niacin or vitamin PP, and vitamin E. While for the latter there is no need to remember its antioxidant properties, for vitamin PP perhaps not many know that it also performs this action after its conversion to NAD (an enzyme cofactor) in our body.
In its constitution polyphenolic molecules are included, with a known antioxidant activity, which are present both in the seed and in the cuticle. Finally, it is among the very few natural products to contain coenzyme Q10, a molecule that cells (especially cardiac) use for their breathing. But if on the one hand the nutritional properties of this seed are to be praised, the same can not be said of its intrinsic allergenic properties on certain individuals. Given that peanut allergy is considerably less common than gluten allergy, milk protein or eggs, it can be said that it occurs in 92% of cases in children within 7 years of age, with an incidence of almost 12%, posing as a third cause of food allergy after milk and eggs. The allergy also has a prevalence of 1.4% among American children, 3.2% in the British and seems to remain for life, which is not the case for previous foods.
In the United States of America, there are an average of 200 deaths every year due to severe allergic reactions caused by peanut-based foods. The specific allergic reaction can occur by contact, inhalation but especially by ingestion, with symptoms that can range from simple skin or mucosal reactions to an asthmatic attack, to angiogenic edema to arrive at a potentially fatal anaphylactic shock. In the Mediterranean area, more than half of those sensitive to peanuts show a curious reaction to the labial and oral mucosa, which very rarely extends to actual symptoms. Although the problem of this allergy concerns specific areas of the globe, the growing spread of peanuts and other dried fruit as an ingredient for confectionery products or snacks, has allowed the identification of subjects who were not aware of the problem. Those responsible for peanut allergic manifestations are its proteins.
Their main characteristics are resistance to thermal denaturation, followed, for some of them, by the attack on digestive proteases. Thirteen identified so far, but the highest percentage of presence is divided between Ara-h1, -h2 and -h3. Ara-h2 has direct anti-trypsin activity, thus interfering with the digestion of the proteins themselves. As it has been established that the digestive proteases (pepsin, trypsin, chymotrypsin) have no effect on the abolition of their allergenic capacity, it has been attempted to macerate peanut seeds with papain (papaya juice) and bromelaine-type proteases (from pineapple juice). The posthumous analysis of proteins showed that a more extensive proteolysis had occurred, such as to justify a loss of a good part of their antigenicity.
The other directions explored, although anti-economic in their immediate feasibility, are the production of modified peanuts with genetic engineering. Knowing the basic proteomics of peanut proteins, it has been speculated that the variation of some DNA bases in specific segments of their sequence, could lead to the synthesis of their variants with greatly reduced antigenic power. The abolition of the expression of the most allergenic proteins has been excluded a priori, given their preponderance of seed constitution (almost 70%). In this way, the food properties of the peanut can be preserved, which, once again, are considerable. Apart from their richness in glutamine, cysteine and arginine, Ara proteins also contain a good quantity of essential amino acids such as lysine, leucine, phenylalanine and tryptophan.
Given the importance of this type of allergy, and of the types of peanut-based food products that are becoming increasingly widespread, various solutions have been proposed to the problem. There are preventive solutions, both screening kits for the detection of a safe predisposition, and suitable pharmacological preparations. These consist of cocktails of two or three molecules able to counteract as quickly as possible the onset of the most serious clinical symptoms (anti-histaminic and ultra-fast steroids). Some research groups have focused their efforts towards classical immunotherapy, based on the administration of antigenic fragments (peptides) of the Ara proteins, in order to evoke an antibody response comparable to that obtainable with a classic vaccine.
The approval by the US Food and Drug Administration (FDA) of Palforzia in January 2020, the first drug approved for FA in the form of peanut oral immunotherapy (OIT), is a first step towards safe and effective treatments for FA. Palforzia is a highly characterized and standardized peanut OIT formulation, produced by removing fats (defatting) from peanut flour. There have been two small studies on this drug involving complexively 670 people. In the first study, 50% of the patients aged 4 to 17 could tolerate 1 mg of peanut protein with only mild symptoms, compared with 2% of those who received placebo. In the second study, 58% of 4- to 17-year-olds could tolerate the same dose of peanut protein with only mild symptoms compared with 2% of those who took placebo. However, research into further optimization of peanut OIT for efficacy, safety and ability to improve participants’ quality of life is still ongoing.
Finally, it is known that it has long been mandatory for food industries to highlight the presence of peanuts, either as an ingredient of their products or as a possible contaminant. The latter case usually occurs when the production plant uses peanuts for other products that have shared the same production line. On the market there is the possibility of finding peanut butter substitutes, prepared with a base of rice flour and legume extract, then flavored with soy lecithin, hazelnut, etc. Until now, waiting for a food solution that is as genuine and original as it is safe, the only possibility for people suffering from allergy to this seed is the exclusion from the diet of any food containing peanuts as an ingredient and, with caution, try to avoid them when present in small quantities.
- edited by Dr. Gianfrancesco Cormaci, PhD, specialist in Clinical Biochemistry; and Dr. Danilo Ciciulla – Food Technologist and Auditor.
Sharma V et al. PLoS One. 2020 Dec 3; 15(12):e0241648.
Blumchen K et al. J Allergy Clin Immunol Pract. 2019; 7:479.
Vickery B.P., Vereda A. N Engl J Med. 2018; 379:1991–2001.
Loh W, Tang MLK. Int J Environ Res Publ Health. 2018; 15:2043.
Burbank AJ et al. Immunol Allergy Clin. 2016; 36:55–69.
Iqbal A et al. Food Nutrition Res 2016; 60:28945-952.
Fleischer DM et al. J All Clin Immunol 2015; 136(2):258-61.
Bublin M et al. Curr. Allergy Asthma Rep 2014; 14:426.
Ratnaparkhe MB et al. Genome Biol. Evol. 2014; 6(9): 2468.
Xu YS et al. Allergy Asthma Clin Immunol 2014; 10(1):38.
Bublin M et al. Int Arch Allergy Immunol. 2014; 165:179-94.
Starkl P et al. Clin Exp Allergology 2012; 40(2):1408-12.
Albrecht M et al. J Allergy Clin Immunol 2009; 124(2): 328.
Mills et al. Trends Food Sci Technol 2003; 14:145-46.