Science at Work: Food Allergies, Food Intolerances, and Mysterious Diets

FAF_-_Big8food-allergens.34290002_stdToday we unravel the following:   what is the difference between food allergies and food intolerances, and why are so many people giving up foods like gluten?

Food Allergies

Allergies of all kinds happen when the body’s immune system reacts to an innocuous substance (in my case, grass, in my daughter’s case, peanuts) as though this substance is poisonous.  Most environmental allergies cause symptoms like itchy red eyes, runny nose, cough, and sometimes hives.  I spend the entire spring season feeling like I have the worst cold imaginable.  But no matter how wretched I feel, I know that I am not going to die from my grass allergy.  Food allergies, on the other hand, can be fatal.

Food allergies are tricky because they often cause the body to go into anaphylactic shock (this is especially common with peanut, tree nut, and shellfish).  Food Allergies For Dummies, a book I highly recommend, defines anaphylaxis as “An immediate, severe, and sometimes fatal allergic reaction that can cause respiratory failure or shock due to an extreme drop in blood pressure”.  Basically, when you die of anaphylactic shock, you die of cardiac arrest or because your throat swells shut so tightly that it suffocates you to death.

The most common food allergies in the United States are to peanuts, tree nuts, shellfish, soy, dairy, eggs, fish, and wheat.  People living with food allergies must carry epinephrine at all times (in the form of an EpiPen or an Auvi-Q) and must use great caution especially when eating out.  According to F.A.R.E (Food Allergy Research and Education), up to 15,000,000 people in the US have food allergies, and a person goes to the emergency room for treatment related to food allergy reactions every three minutes.  According to F.A.A.N (Food Allergy and Anaphylaxis Network) there are an estimated 100 – 200 deaths in the US from anaphylaxis each year.

There are a couple of things to keep in mind about these statistics.  One is that they are controversial.  Some think food allergies are under-reported, because they may be mis-diagnosed.  Others think they are over-reported, because they may be being mis-diagnosed in the opposite direction.  Some people try to diagnose themselves and may have an intolerance as opposed to an allergy.  There are also concerns about bias, since the leading food allergy advocacy groups that do a lot of the statistical research also have a monetary interest in keeping the issue alive.

The other thing to keep in mind is that the statistics don’t reflect the whole picture.  On the one hand, deaths from food allergies are clearly very rare, especially when you take into account the fact that there are 313.9 people in the US (as of 2012).  But this doesn’t reflect why the death rate is so small amongst such a high population of sufferers.  Most people with severe food allergies survive not because their allergies are inconsequential, but because these people are unrelentingly careful, just as most people don’t die from chugging rat poison out of a bottle because we know that will kill us and therefore we avoid consuming it.

Food Intolerances

Food intolerance is when the body can’t digest a food properly.  One of the most common food intolerances is to lactose (which is found in dairy products).  Lactose intolerance is different than an allergy to milk.  In lactose intolerance, the body doesn’t make enough of an enzyme called lactase to properly break down lactose, and this causes gas, bloating, and other stomach problems.  Another common intolerance is to gluten, and this occurs when the body can’t break down the proteins found in gluten.  Celiac disease is a specific kind of intolerance in which “gluten ingestion triggers your white blood cells to attack the lining of you small intestine”.  Other common food intolerances are to sulfites (these can cause asthma and headaches, and are the reason that migraine sufferers are often told to avoid wine and chocolate), and, to a much lesser degree, food additives.

A food intolerance can be mild or severe.  Let’s say you have a friend who is lactose intolerant.  She might tell you that since it’s her birthday she’s going to have just one piece of pizza.  She may have no problems with a small amount of the problem food or she may have just very mild symptoms – one that she avoids most of the time but is willing to live with occasionally when she really craves something, like that one piece of pizza.  But, it’s also possible that your friend absolutely can’t have any lactose at all.  She may experience severe vomiting or diarrhea after just the smallest exposure to lactose.  So do not take food intolerances lightly unless you want your friend to vomit on your shoes.

Main Differences Between Allergies and Intolerance

Food allergies and intolerances can be confusing, because often people with intolerances will say they have allergies – sometimes because they don’t understand the difference, but usually because it’s simpler and it’s easier to get people to take your food issue more seriously when you call it an allergy.  And basically, the deal is the same – if you eat the offending food, you will feel awful.  For practical, non-medical purposes, the main differences to remember are that intolerances aren’t fatal but allergies sometimes are, and that jabbing your friend who has an intolerance with an EpiPen isn’t going to help.

  • Someone with a food intolerance can often have small amounts of the problematic food.  To someone with food allergies, especially someone with severe allergies, even trace amounts of the allergen can be fatal.
  • Food allergies involve the immune system and food intolerances do not (Celiac disease involves the autoimmune system, but not in the same way that an allergy does).
  • If someone is having an allergic reaction, they can be treated with epinephrine and/or an antihistamine (not always with success).  These won’t help someone with an intolerance.

Avoiding A Food For General Health Reasons

Lately, an increasing number of people have been avoiding various foods based on ideas that these foods may be bad for everybody or may be bad for them in a previously undiagnosed, undramatic way (meaning – they cause chronic problems, not sudden bouts of gastrointestinal distress).  The most common one you’ll hear referred to is gluten.  Some research suggests that our bodies simply aren’t evolved to properly digest gluten (this research is, to use a scientific term, iffy).  Some people swear that cutting out gluten (or sugar, or dairy, or soy, or some combination) makes them feel better – thinner, more energetic, and healthier overall.

So what’s up with these mysterious diets?  Do they work?  There’s no definitive science that says that you should avoid a kind of food unless you have a concrete reason to – a diagnosed allergy or intolerance.  So what’s going on with you friend who says she feels better since she quit eating gluten?  Well, maybe she really had a low-grade intolerance.  Maybe she feels better because cutting out one or more staple food items makes her eat a more varied menu of whole foods with mainly fruits and vegetables and proteins – hard to go wrong with that.  Maybe she is just being trendy – but I’m being trendy when I spend $3.50 on my cookie crumble frappachino, and nobody gives me a hard time about that.

So respect your friends’ food choices and limitations, whether they are a matter of life and death (as in an allergy), a matter of severe physical distress, (as in an intolerance), or an experiment, (as in elimination diets that aren’t treating an identifiable problem but may or may not be beneficial overall).