Rice in the top three cereals
In many developing countries, rice cultivation provides food security and is the main source of livelihood. China and India are among the largest producers, followed by Indonesia, Vietnam, Bangladesh and Thailand [1]. Rice, together with wheat and maize, accounts for about 90% of all cereal crops produced worldwide [1].
Each region has its own variety of this cereal, which has distinct nutritional values [1]. Rice comes in 25 species and as many as 120,000 varieties – with different colours, flavours, grain thicknesses [2]. The most common species is Oryza sativa (seed rice). In Europe we know mainly:
- white rice,
- black rice
- brown rice,
- basmati rice,
- jasmine rice,
- wild rice,
- golden rice [1].
White is rich in carbohydrates, brown in fibre, black in anthocyanins, wild in antioxidants, golden in vitamin A [1]. However, it is worth knowing, the rice available in Polish shops, is unlikely to come from Asia. For the most part, it is rice from European crops (Italian, Spanish, French) [2].
Rice allergy – not just in Asia
If there was a list of the best-rated foods, rice would certainly be on it. It is associated with an easily digestible diet, so we immediately reach for it when we have stomach problems [9]. It also often appears in weight loss diets, as some of its varieties are extremely low in calories [1]. Products made from rice are also very popular. Rice gruel was until recently an integral part of infant diets. However, at the moment, its contribution to young children’s diets has decreased significantly due to reports related to arsenic contamination [13,14].
Thus, eating rice does not always and does not benefit everyone. It has been proven in scientific studies that this type of cereal can cause or exacerbate:
- IgE-dependent food allergy,
- food protein-induced inflammation of the small intestine and colon (FPIES), which is a type of IgE-independent food allergy (rice, cow’s milk, soy and oats are among the foods most likely to cause FPIES symptoms) [6,10].
In Western Europe, rice is considered to be weakly allergenic (hypoallergenic). Therefore, it was recommended for a very long time to people with atopy (especially severe atopy) [3]. However, studies in Japan have shown that rice (and with it other rare allergens, e.g. chocolate, coffee) can exacerbate the changes that occur in atopic dermatitis [3,5]. In addition, it has been found that rice sensitisation is more common in allergic asthma patients than in other allergic individuals [3].
Cases of confirmed rice allergy are few – despite such a high proportion of this cereal in the diet of people worldwide. They mainly occur in regions that are famous for rice cultivation, in Asian countries, but also outside Asia, such as in Europe (northern Italy) [6].
Rice – allergens, cross reactions
Hypersensitivity reactions to rice may result from cross-reactions with other cereals. The risk of such reactions applies mainly to those allergic to wheat (wheat cross-reacts with rye, rice, barley and soybean) [3].
In addition, the most clinically relevant rice allergen – from the lipid transfer protein (LTP) group – shows strong similarity to the Pru p 3 protein, the main allergen of peach. Allergic reactions to rice can therefore occur in people with peach allergy [6].
Symptoms of rice allergy
The most common symptom of this type of allergy is contact urticaria caused by raw rice [7]. Respiratory symptoms (rhinitis, asthma attack, dyspnoea) can occur after inhaling raw rice dust or cooked rice fumes, as well as after eating rice. In addition, eating rice by an allergic person can cause gastrointestinal symptoms (nausea, abdominal pain, diarrhoea) and generalised reactions (affecting the whole body), e.g. anaphylaxis, angioedema. With rice allergy, exercise-induced anaphylaxis (FDEIA) also occurs in rare cases [11].
How to diagnose?
The primary method for diagnosing rice allergy, like any other food allergy, is an oral provocation test (performed by a doctor) [12]. To check for a reaction to the allergens contained in rice, skin tests are also performed. On the other hand, sIgE antibody levels can be checked by diagnostic blood tests, such as panel or multiparameter tests. For people in whom rice causes symptoms on skin contact, patch (epidermal) tests are performed for diagnostic purposes.
