概述

食物过敏是指进食特定食物不久后出现的免疫系统反应。即使是一丁点致敏食物也会导致荨麻疹、气道肿胀和消化问题等症状。有些人的食物过敏可能会导致严重症状，甚至出现全身性过敏反应这的一种危及生命的反应。

约 8% 的 5 岁以下儿童和约 4% 的成人患有食物过敏。食物过敏尚无治愈方法，但有时会随儿童年龄的增长而自愈。

人们很容易将食物过敏与更常见的食物不耐受反应混淆。食物不耐受虽然令人烦恼，但并不累及免疫系统，相对并不严重。

症状

对有些人来说，对某种特定食物的过敏反应可能引发不适感，但并不严重。但对其他人，食物过敏反应可能会令人恐惧，甚至危及生命。食物过敏症状通常在食用致敏食物后几分钟到两小时内出现。在极少数情况下，症状可能延迟数小时出现。

最常见的食物过敏症状包括：

  • 口腔麻刺感或发痒。
  • 荨麻疹、瘙痒或湿疹。
  • 嘴唇、面部、舌头和咽喉或身体其他部位肿胀。
  • 腹部疼痛、腹泻、恶心或呕吐。
  • 哮鸣、鼻塞或呼吸困难。
  • 头晕、头重脚轻或昏厥。

Anaphylaxis

A food allergy can trigger a severe allergic reaction called anaphylaxis. This can cause life-threatening signs and symptoms, including:

  • Tightening of the airways.
  • A swollen throat or the sensation of a lump in your throat that makes it hard to breathe.
  • A drop in blood pressure.
  • Rapid pulse.
  • Confusion or other changes in mental status.
  • Dizziness, lightheadedness or loss of consciousness.

Emergency treatment is critical for anaphylaxis. Untreated, anaphylaxis can be fatal.

何时就医

如果您进食后不久出现食物过敏症状，请咨询医疗护理专业人员或过敏症专科医生。如有可能，在出现过敏反应时到医疗护理专业人员处就诊。这有助于作出诊断。

如果出现以下任一严重过敏反应的症状，请寻求急救护理：

  • 气道收缩导致呼吸困难。
  • 休克且血压急剧下降。
  • 脉搏过快。
  • 头晕或头重脚轻。

病因

如果您出现食物过敏，免疫系统会误将某种特定食物或食物中的某种特定物质识别为有害物质。作为回应，免疫系统会触发细胞产生一种被称为免疫球蛋白 E（IgE）的抗体，以识别致敏食物或食物成分（称为过敏原）。

下次再食用这种食物时，哪怕只是最小份量，IgE 抗体也能感知。它们随即向免疫系统发出信号，让免疫系统向血流中释放一种被称为组胺的化学物质以及其他化学物质。这些化学物质会引起过敏症状。

大多数食物过敏是由下列物质中的某些蛋白质引起的：

  • 虾、龙虾和螃蟹等甲壳类水生动物。
  • 花生。
  • 核桃和美洲山核桃等坚果。
  • 鱼类。
  • 鸡蛋。
  • 牛奶。
  • 小麦。
  • 大豆。

Pollen-food allergy syndrome

People who are allergic to certain pollens may be allergic to certain raw plant foods. But people usually have no reaction if the food is cooked or processed. This condition is called pollen-food allergy syndrome or oral allergy syndrome. The following plant allergens are linked to possible food allergies.

Birch pollen. If you are allergic to birch pollen, you also may have a reaction to several foods.

Fruits

  • Apple
  • Apricot
  • Cherry
  • Peach
  • Pear
  • Plum

Nuts and legumes

  • Almond
  • Hazelnut
  • Peanut
  • Soybean

Herbs and seeds

  • Aniseed
  • Caraway seed
  • Coriander
  • Fennel
  • Parsley

Vegetables

  • Carrot
  • Celery

Ragweed pollen. If you are allergic to ragweed pollen, you also may have a reaction to some foods.

  • Banana
  • Cantaloupe
  • Cucumber
  • Honeydew
  • Watermelon
  • Zucchini

Grass pollens. If you are allergic to grass pollens, you also may be allergic to several foods.

Fruits

  • Cantaloupe
  • Honeydew
  • Kiwi
  • Orange
  • Tomato
  • Watermelon

Legumes

  • Peanut

Vegetables

  • Swiss chard
  • White potato

Mugwort pollen. If you are allergic to mugwort pollen, you also may be allergic to several foods:

Fruits

  • Bell pepper
  • Grape
  • Peach
  • Lychee
  • Mango

Herbs and seeds

  • Aniseed
  • Black pepper
  • Caraway seed
  • Coriander
  • Fennel
  • Paprika
  • Mustard
  • Parsley
  • Sunflower seeds

Vegetables

  • Broccoli
  • Cabbage
  • Carrot
  • Cauliflower
  • Celery
  • Garlic
  • Onion

Exercise-induced food anaphylaxis

Some people may experience an anaphylactic allergic reaction if they do moderate or strenuous exercise a few hours after eating certain foods. Most commonly this happens after eating wheat or shellfish. If these people don't exercise after eating the allergen, they don't have an allergic reaction.

Other reactions

Other reactions to food may have symptoms similar to food allergies, but activities in the body other than immune system reactions are involved.

Food intolerance is when the body cannot digest certain foods or break down nutrients in foods. A food intolerance may cause digestive symptoms similar to allergic reactions:

  • Excessive gas.
  • Bloating.
  • Cramping or stomach pain.
  • Diarrhea.

Examples of food intolerance include:

  • Lactose intolerance is the result of the body not being able to break down the main sugar in milk called lactose.
  • Gluten sensitivity is the result of the body not being able to break down a protein called gluten that is in wheat, barley and rye.

Food poisoning is a sickness people get from something they ate or drank. The causes are germs or other substances in the food or drink. Symptoms most often start within hours or days of eating the food.

Sensitivity to additives in certain foods can cause symptoms similar to allergic reactions. For example, sulfites used to preserve dried fruit, canned goods and wine can trigger asthma attacks in people with severe asthma.

Celiac disease is an immune system reaction to gluten, but it's a unique reaction that's different from a typical food allergy. It does not cause anaphylaxis. The immune system reaction to gluten causes damage to the small intestine and leads to an inability to absorb certain nutrients.

风险因素

食物过敏的风险因素包括：

  • 家族史。 如果哮喘、湿疹、荨麻疹或过敏（例如花粉症）是您家族中的常见状况，则您出现食物过敏的风险会较高。
  • 其他过敏。 如果您已对一种食物过敏，则您对其他食物过敏的风险可能会较高。同样，如果您有其他类型的过敏反应（如花粉症或湿疹），您出现食物过敏的风险更高。

  • 年龄。 食物过敏在儿童中更常见，尤其是婴幼儿。随着儿童年龄增长，其消化系统会逐渐成熟，身体对引发过敏的食物成分产生反应的可能性也会降低。

    幸运的是，儿童通常会随年龄增长而不再对牛奶、大豆、小麦和鸡蛋过敏。对坚果和贝类的严重过敏和过敏更可能伴随终身。

  • 哮喘。 哮喘和食物过敏通常会同时发生。在这种情况下，食物过敏和哮喘的症状都更易加重。

可能增加全身性过敏反应的发生风险的因素包括：

  • 有哮喘史。
  • 是青少年或儿童。
  • 延迟使用肾上腺素治疗食物过敏症状。
  • 没有荨麻疹或其他皮肤症状。

预防

早期暴露

尽早食用花生制品可以降低花生过敏的风险。在一项重要的研究中，选择高风险婴儿（例如患有特应性皮炎、对蛋类过敏或两者都有的婴儿）从 4 到 6 个月至 5 岁期间或是摄入、或是避免花生制品。

研究人员发现，经常食用花生蛋白（例如花生酱或花生味零食）的高风险儿童患花生过敏的几率要低 80% 左右。

在食用过敏性食物之前，请与孩子的医疗护理团队讨论提供这些食物的最佳时间。

来自妙佑医疗国际员工