Latin name: Spinachia oleracea
Source material: Freeze-dried spinach
Common names: Spinach, Savoy spinach
The Spinach plant is indigenous to the Middle East. Spinach was subsequently grown in Spain from the 8th century, and it was the Spaniards who eventually introduced it to the United States. Spinach is now produced widely throughout the world for its edible leaves. It is the only edible vegetable in the Chenopodiaceae (Spinach) family. Two varieties exist: Savoy (wrinkled-leaf) and Semi-Savoy (flat-leaf).
The plants are grown from seed and harvested while young and tender. Varieties differ in their leaves from smooth and broad to arrow-shaped to savoyed or wrinkled, but all leaves are non-hairy. Their colour tends to be dark green. Since winter-hardy varieties of this annual are available, Spinach can be eaten year-round.
Spinach is not known in the wild. Large quantities are grown commercially for canning and freezing, as well as for fresh consumption. Spinach may be used raw in salads, or cooked (usually by boiling or sautéing) as a vegetable or as part of another dish. Many dishes that have Spinach as an integral ingredient are described with the phrase à la Florentine. The seeds can be eaten raw or cooked, or can be sprouted and added to salads. Spinach is a rich source of iron as well as of vitamins A and C. But because Spinach contains oxalic acid – which inhibits the body’s absorption of calcium and iron – the nutritional value is somewhat diminished. Some modern varieties have been developed that are low in oxalic acid. Spinach contains high levels of histamine; reactions may be indistinguishable from an IgE-mediated reaction.
The plant is carminative and laxative. In experiments, it has been shown to have hypoglycaemic properties. It has been used as a remedy for a variety of complaints.
Chlorophyll extracted from the leaves is used as an edible green or yellow dye.
Spinach extract contains a 20 and a 25 kDa protein, as well as 14-18 kDa proteins (minor bands on blot). One or more proteins appear to be heat-stable (1). A cross-reactive 30 kDa protein has also been detected (2).
The following allergen has been characterised:
An extensive cross-reactivity among the different individual species of the genus could be expected, as well as to a certain degree among members of the family Amaranthaceae (4). Cross-reactivity has been reported between Spinach and Chard, as might be expected (5, 6).
A single report was made of anaphylaxis to Spinach and concomitant oral allergy syndrome to Mushroom. Cross-reactivity was demonstrated between these 2 foods, and the authors suggest that this may be due to common epitopes (1). A subsequent study identified a 30 kDa protein in each food, which inhibition assays confirmed to be related and a relationship was demonstrated between allergy to moulds (Alternaria alternata, Cladosporium herbarum and/or Aspergillus fumigatus) and positive skin prick tests with Mushroom (Agaricus bisporus) and/or Spinach (2).
A study reports on the possible cross-reactivity between Spinach and Latex (two cases of cross-allergenicity between Latex and Spinach have been reported previously) (6-8). The authors suggest that there may be a common epitope (9-10).
Spinach can induce symptoms of food allergy in sensitised individuals (1,5-6,10).
Oral allergy syndrome induced by Spinach has been reported (5).
Two anaphylactic episodes to Spinach occurring in a 31-year-old were reported. She also developed oral allergy syndrome to Mushroom, and cross-reactivity was demonstrated between these 2 foods. Skin reactivity was not detected to commercial extract of Spinach, but instead to fresh raw and boiled Spinach (1).
Exercise-induced anaphylaxis associated with food allergy to Spinach has been reported (10).
A 54-year-old female working as a vegetable farmer presented with painful pruritic skin lesions on both hands. Physical examination showed hyperkeratotic fissured eczema. RAST, prick, and patch testing revealed type I and IV hypersensitivity to Spinach, ruccola, and chives, so that a protein contact dermatitis was diagnosed (11).
A 51-year-old woman developed hypersensitivity pneumonitis to Spinach powder used as a food dye (12). A 30-year-old man with chronic occupational rhinitis and asthma as a result of exposure to Spinach powder in a factory was described. Spinach-specific IgE was 15.4 kUA/l. Ten minutes after handling the dried Spinach powder, he experienced the onset of dyspnoea. Eight hours later, there was recurrent dyspnoea and another decrease in FEV1, accompanied by fever and arthralgia (13).
Phytodermatitis due to contact with Spinach has been reported (14).
Spinach contains a high level of histamine, and the differentiation of IgE-mediated reactions from pseudoallergic reactions caused by the histamine is important (5).
Due to the presence of oxalates, people with a tendency to rheumatism, arthritis, gout, kidney stones or hyperacidity should use special caution if including this plant in their diet, since it can aggravate their condition.
Compiled by Dr Harris Steinman, developer of Allergy Advisor, http://allergyadvisor.com
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