Allergy or intolerance?
Technically an allergy is an immunological over-reaction to a substance. In food terms it may be ‘overt’ (ie. obvious – eg to peanuts, nuts and shellfish – like an allergy to pollen or dogs) or ‘masked’ (like gluten or dairy allergy).
An intolerance is a general term and covers any difficulty you have with a food. it is a better word to use unless you know for sure you have an allergy.
We sometimes ask ourselves “is this food suiting me?”
Sometimes it can be easy to spot a problem: you get some uncomfortable reaction soon after eating something like bread or cheese or wine or something else. For example there are some ‘trigger foods’ that are well know to lead to migraine headaches, acid stomach or bowel looseness.
Most often however you have a suspicion about a food, you think it may lead to a problem but are not sure, or you read something that says this food has caused problems, or you go to an alternative practitioner who tells you that you are ‘allergic’ to this or that.
There are only a few sure ways to test that you have an allergy or intolerance. A ‘prick test’ at a hospital or medical centre can sometimes pick up an overt allergy. A stool test can sometimes pick up a food intolerance or gluten allergy. However the evidence for the reliability of other techniques like hair analysis, vega testing, pendulums and iridology is lacking and sometimes clearly contradictory. At best they can point to something you could look to find out for once and all.
The only reliable way to find out whether a food is causing you any problems is to set up your own experiment. If you do have a problem with a food your symptoms will improve if you remove the food for a while, and will reappear when you introduce (‘challenge with’) the food again.
Cutting out and reintroducing a suspect food is called a food elimination test. It is generally safe to do at home if you follow the guidance below. In the two weeks or so that you will be eliminating the food there is almost no chance of dietary deficiencies occurring. However if you are seeing your doctor for any reason, do say that you are planning to do this and check that it is OK.
Conducting a food elimination
Generally it is simpler, safer and most revealing to test one food category at a time. There are some single foods that may be suspect but most often they come in categories. To get a clear result you must completely remove all traces of that category for the test. If you find that you get a positive result to one of the categories you can go back later and see if it applies to all or just one or two ingredients.
In order of likelihood of causing difficulties, below are the main food groups to consider.
Wheat and wheat products (bread, pasta, cakes, biscuits, sauce thickening etc), oats, barley and rye products. Exclude also spelt, bulgar and other wheat variations. Note also wheat-based crisps (US ‘chips’), tortillas, and flat-bread rolls. Cereals are used often as an ingredient to thicken sauces, soups and other unexpected products – so read labels carefully – it is probably best to avoid eating out during your elimination test.
You CAN substitute rice, corn, millet, semolina (eg. the original Morroccan couscous), buckwheat, and gluten-free flour products. Do check packets carefully if in doubt – for example most western couscous is wheat.
Cow’s milk, cheese, yoghurt, butter, cream, ice-cream, custard, and any food containing these ingredients, ‘dairy solids’, ‘lactose’ or rennin. For the purposes of a thorough elimination it is usually a good idea to drop goat or sheep milk products as well (some difficulties are with the milk sugar lactose). DO read labels and avoid other people’s or prepared meals as they often contain butter or other dairy ingredients.
You CAN use soya, nutmilks and tofu as temporary substitutes during the elimination.
As well as eggs on their own, cut out mayonnaise, custard, ice-cream, cakes, biscuits and sauces, look at the ingredient list on the side of any prepared food.
Tomatoes, potatoes, aubergines (US ‘eggplants’), okra and peppers, capsicums, cayenne and chillies.
Excludes also potato-based crisps (US ‘chips’), most sauces for pasta and pizza, most Italian and Mexican food, many Indian dishes. Note that potato flour is a common ingredient of gluten-free flour,
Cabbage, broccoli, Chinese cabbage, kale, swede, turnip, cauliflower, kohl rabi, calabrese, Brussels sprouts, mustards, and horseradish.
Other categories are generally self-explanatory. If you suspect fish, shellfish, mushrooms, nuts or seeds then look through every meal or pack of food to make sure traces of your suspects are not present.
Food elimination procedure
- You should allow 2 weeks to conduct the test.
- Having chosen your suspect food clear your fridge or cupboard of any foods that you might have to eat and plan your menu for the duration of the test. Take time to plan this properly!
- You should aim to eat 0% (= none!) of the suspect food or foods that may contain the suspect ingredients – even a trace can ignite the immune response. Read all labels carefully and as far as possible make up foods yourself from ingredients you know.
- Avoid take-away foods or eating out as you cannot be sure what is in prepared foods without labels.
- Use the Food Diary in this workbook to record the changes you make in your diet and any changes in symptoms over the 2 weeks.
- At the end of the 2 weeks reintroduce the suspect foods and complete the Diary for a further week. Review the differences while on elimination and after reintroduction.
- You can try the pulse test when you first reintroduce a food. Sit quietly for a half-hour with the test food close to hand. Count your pulse rate for a minute. Eat a mouthful of food. Count again over the next 15 minutes. The pulse will usually go up because digestion is kicking in: if more than 10 pulses a minute there may be an internal reaction to the reintroduced food (this only happens after an elimination).
- DO go back onto the food unless it is still suspect – it is probably fine and is likely to be good for you!
- Wait at least another week before trying another elimination.
- If you do conclude after this that you should eliminate a class of food it will then be worth looking further into the group to see if you can narrow the suspect list down. For example a gluten reaction may be only to wheat, or only to leavened wheat (ie with yeast – like in bread). A dairy reaction may be only to cow’s products, or only to cheese, or only to hard cheese. You should repeat the process testing a narrower band of foods, after a gap of a week to allow the body to adjust to the changes you have made already.
- It is also worth rechecking any food where cutting it out seems to lead to improvements. Sometimes this effect can be temporary and you may still be cutting out a perfectly good food because of a short-term difficulty. It is also the case that cutting out a difficult food for some weeks gives the body a chance to recover and accept it happily again.
There are two types of food most associated with increasing weight – saturated fats, and refined (or ‘simple’) carbohydrates.
Fact: saturated fats are solid at room temperature; unsaturated fats are liquid though may solidify in the fridge.
The case against saturated fats is well established. Eating meat from farmed animals, particularly beef, lamb, pork and even chicken, as well as from cow’s milk products like butter and cream, leads to the consumption of relatively high levels of fats that build up in the blood stream and also increase cholesterol levels.
In the past these fats were not such a problem because people exercised more and were able to burn them off. In the distant past they also ate more wild meat, which is known to have less saturated fat. Exercise is always central to weight control.
Nowadays if you want to control your weight, and especially other risks of being overweight (heart and circulatory disease and diabetes), it is advisable to cut back on the proportion of your protein that comes from the foods mentioned above. Switching to foods with more unsaturated fats like olive, sunflower or rapeseed oils, fish oils is usually a smart move.
See also the Harvard Medical School extended GI list
In recent times the case against simple carbohydrates – refined flour and especially sugars – has become even stronger than that against fats. Fats actually convert to sugars in the body, but these are dwarfed by dietary sugars and refined carbohydrates that are converted too quickly into blood glucose after eating.
It’s the rate of rise of blood glucose that is the problem. This leads to a bigger surge in insulin production by the body. Insulin is the hormone that packs the blood glucose into the tissues where is can be used as fuel. Insulin is very efficient. If too much is stimulated it tends to lower the blood sugar too fast and then overshoot so that levels actually tend to fall. Other hormones have to jump in to prevent this, and thus there is a wider disruption of hormone activity in the body. More immediately there is a common sign of insulin overshoot – you need to get some more sugar in quickly. You feel like something sweet soon after eating! This is called (reactive) hypoglycaemia. Obviously taking more sweet keeps up the blood sugar roller coaster.
We now know that the strain on insulin response leads to increasing difficulty, first with ‘insulin resistance’ (‘metabolic syndrome’ or pre-diabetes) and later Type 2 diabetes. This is associated with increased weight, greater risk of heart and circulatory disease like strokes, and a growing list of troubles.
There is now a simple system of telling how likely a food is to stress your insulin response and to upset your blood sugar levels. It is called the Glycaemic Index (GI).
The American Diabetes Association defines GI as –
a ranking of carbohydrates on a scale from 0 to 100 according to the extent to which they raise blood sugar levels after eating.
Foods with a high GI are those which are rapidly digested and absorbed and result in marked fluctuations in blood sugar levels.
Low-GI foods, by virtue of their slow digestion and absorption, produce gradual rises in blood sugar and insulin levels, and have proven benefits for health. Low GI diets have been shown to improve both glucose and lipid levels in people with diabetes (type 1 and type 2). They have benefits for weight control because they help control appetite and delay hunger. Low GI diets also reduce insulin levels and insulin resistance.
Below is a list of carbohydrate foods ranked by GI. If you are overweight, with risks of diabetes or circulatory disease, shift your diet towards ‘smart carbs’ with low GI, It is best to make sure high GI ‘simple carbs’ are well balanced with more of the smart ones.
Note that the list is not a health ranking. Some otherwise good foods can have a high GI rating.
As well as fats and sugars there are well-understood food ingredients that are known to add weight, stress blood sugar management and risk disease, but which are often ignored.
Many people are not aware of the calories contained in alcoholic drinks. In addition a major report has indicated that alcohol may increase other food intake, especially among those who are already overweight.
High fructose corn syrup
This industrial sugar substitute was introduced into the USA in the 1980s due to the higher cost of sugar there. It is very widespread in American convenience foods, soft drinks, cereals, and even breads, and is becoming widely used elsewhere. There are concerns that high fructose may increase fat levels, encourages more eating and that it has contributed significantly to the rising levels of sugar consumption.
The evidence is still in balance but best advice at this stage is to be careful how much convenience food and sugar of any sort you eat if you are managing your weight. It will be much better to take a little more time to shop for simple foods that you can put together at home: this can also be just as cheap.
Increasing salt in your diet, especially without exercise to lose it in the sweat, leads directly to increased fluid retention because the body needs to dilute the salt. This both means an increase in weight and also an increased risk of raising blood pressure.
Salt levels are being reduced in many convenience foods but are still too high on average. Best make your own food and train yourself to cut back on the use of the salt at home. After a little while of cutting back you will stop liking it so much.