Food Allergies: The Top Ten Offenders

The following three allergens, shellfish, fish and soy, are part of the top 8 allergens that affect 90% of allergic individuals worldwide. Though allergies to these foods are slightly less common than cow’s milk, egg, peanut and tree nut allergies, they are still ever present in many of the foods we eat today. Not only are they a hazard to allergic individuals, these 3 ingredients have been linked to sensitivities and various health conditions.

Food Allergy Research and Education
Health Canada
Current Allergy and Asthma Reports
Clinical and Experimental Allergy
Alternative Therapies in Health and Medicine


Shellfish are a type of sea life that include molluscs, such as oysters and clams, and crustaceans, such as lobsters and crabs. They are commonly found in Japanese cuisine, coastal dishes, oyster sauce, fish sauce and Clamato juice. Shellfish allergies (found in 0.1% of North American children and 2.0% of adults) are fairly common and are often caused by the protein tropomyosin which is found in many different types of shellfish. These allergies generally present themselves at random as a person ages, though they can be brought on by constant exposure. For example, those who often handle shellfish are likely to get sensitized to it, causing contact dermatitis and asthma. It is also a common misconception that such reactions can also occur after the use of iodine and radiocontrast material in individuals allergic to shellfish, though this has not been proven. In fact, studies have shown that having a shellfish allergy has no affect on one’s risk of reaction to radiocontrast dye.

For those of us that can enjoy shellfish, we may have to be cautious around shellfish caught in the Pacific ocean in the future. Some would argue that due to leakage from the Fukushima power plant, sea life within the Pacific ocean is being exposed to radioactive material. This event has caused many to be concerned about consuming Pacific shellfish. As it stands now, the FDA has stated that they are actively testing foreign and domestic shellfish and have yet to find anything that would be a threat to public safety. The FDA has further stated that if they do happen to find any unsafe shellfish, they will remove it from the U.S. markets. Therefore, any shellfish currently available for sale today is safe to eat.

Clinical and Experimental Allergy
Food Allergy Research and Education
Current Allergy and Asthma Reports
The Journal of Emergency Medicine
Food and Drug Administration


Fish are a common staple protein in many coastal countries and are classified by their fat content as whitefish (<1% fat) or oily fish (10%-25% fat). Fish are often found in Japanese cuisine, coastal dishes, Worcestershire sauce and Caesar salad dressing. Allergies to fish (affecting 0.1% of North American children and 0.4% of adults3), commonly caused by the protein parvalbumin, can arise not only with ingestion, but with skin contact and vapour inhalation as well. Such allergies are most prevalent in countries that consume a large amount of fish. Though parvalbumin is present in most fish, its levels are higher in white-muscled fish (like cod), than in dark-muscled fish (such as tuna). Although this protein’s characteristics do not change with cooking, the canning process has been shown to alter allergic responses to fish, possibly causing less severe reactions in allergic individuals when ingested.

As with shellfish, some believe that fish from the Pacific ocean are also at risk of accumulating radiation due to leakage from the Fukushima power plant. In response to these concerns, the FDA has been continuously testing foreign and domestic fish and they have yet to find anything that would be a threat to public safety. If they find any unsafe fish, the FDA has stated that they will remove it from the U.S. markets. Therefore, based on the FDA’s specifications, fish currently available is safe to eat. However, a recent study published in Environmental Science and Technology found that in 2011 and 2012, since the earthquake, there were increased levels of 134Cs in Albacore Tuna caught in the East Pacific Ocean. Given that the study did not find any detectable levels of 134Cs in fish caught in 2008, and found increasingly higher levels in fish caught in 2011 and 2012, it may be likely that fish, and possibly shellfish, could accumulate even greater levels of 134Cs in the future.

Fish and Fish Products
Food Allergy Research and Education
Current Allergy and Asthma Reports
Pediatric Allergy and Immunology
Food and Drug Administration
Environmental Science and Technology


Soybeans are a species of legume (bean) that are used to produce oil, protein powder, tofu, tempeh, miso paste, soy sauce, tamari, and various other Asian foods. Soy allergy affects roughly 0.4% of children, with roughly 50% of children outgrowing the allergy by the age of 712. This allergy has been shown to cause rhinitis and atopic dermatitis, and has also been linked to cross-reactivity with birch pollen, almond, apple, apricot, buckwheat, and many other foods.

Today 85% of North American soy is genetically modified. Provided that certain soy allergens have been found to be 7 times more abundant in GM soy as compared to organic soy, there may be some association between GM soy and soy allergy. Regardless, studies have yet to demonstrate a causal link between GM soy and soy allergy prevalence.

Food Allergy Research and Education
The Journal of Allergy and Clinical Immunology
The Doctors Laboratory
GMO Compass
Biology of Nutrition in Growing Animals
Toxicology Letters

Food Allergies: The Top Ten Offenders

Many of us know of at least one friend or family member that has a severe food allergy. To the average person, these foods are harmless, but to an allergic individual the presence of such allergens can mean the difference between life and death. The reason behind these dangerous reactions is rooted in the immune system’s response to allergenic proteins. An allergic individual’s immune system finds said proteins and reacts much like it would to a cold or flu, by causing inflammation and attacking the “invading” allergenic proteins. Though, unlike a reaction to a virus, the immune system attacks the allergen very quickly, often leading to swelling, rashes and anaphylaxis.


Severe food allergies affect roughly 1 in 21 Americans and 1 in every 13 American children. Though many children outgrow these allergies, the rate of food allergy diagnosis in children has been on the rise in the past few decades. In fact, a recent study by the CDC stated that food allergies in children have increased by 50% between 1997 and 2011, although the cause of this increase is still unknown. What scientists do know is that 8 allergens, including milk, eggs, peanuts, tree nuts, soy, wheat, fish and shellfish, cause 90% of all allergic reactions, while allergens such as mustard, sulfites and others comprise the remaining 10%. Today, we will be discussing the most prevalent food allergens: Cow’s milk, eggs, peanuts and tree nuts. Stay tuned for future blog posts about other common allergens, including soy, wheat, fish, shellfish, mustard and sulfites.

Immunobiology: The Immune System in Health and Disease
Food and Drug Administration
Food Allergy Research and Education
Current Allergy and Asthma Reports
Health Canada


Cow’s milk is a common staple in the Western diet as it is found in butter, yogurt, cheese, cream, pastries, entrées and desserts>. Such products, as well as sheep, goat and buffalo milk, can cause significant side effects for those with Cow’s Milk Allergy. This is one of the most common food allergies in children, affecting 2.5% of North American children and 0.3% of adults. In addition, some children who are allergic to cow’s milk have been shown to be allergic to soy milk, as well.

Individuals with milk allergies often avoid milk-containing foods, but likely do so with the fear of getting osteoporosis when they get older. Therefore, those with milk allergies should note that a recent meta-analysis published in the American Journal of Clinical Nutrition in May 2009 found that “osteoporotic bone fracture rates are highest in countries that consume the most dairy”. In addition, they stated that “most studies of fracture risk provide little or no evidence that milk or other dairy products benefit bone”.

Allergies aside, milk-drinking individuals should also be aware that recently the International Dairy Foods Association petitioned the FDA to allow artificial or non-nutritive sweeteners to be unlabeled on milk products. Though the ingredients would still be shown in the ingredient list, the front label would no longer have to contain the words “reduced-calorie”. This would mean consumers could unknowingly choose artificially sweetened milk over natural milk—a choice many of us would still like the power to make. Given that this petition has not yet been accepted, the current labeling standards still apply.

Current Allergy and Asthma Reports
Web MD
Annals of Allergy, Asthma and Immunology
Mayo Clinic
The American Journal of Clinical Nutrition
Food and Drug Administration


Eggs are produced by birds, reptiles, amphibians, and fish, though humans consume chicken eggs most often. Chicken eggs are used in many different foods including mayonnaise, sauces, breads, batters and pastries. Egg allergies (which affect 1.3% of North American children and 0.2% of adults) are often caused by proteins found in the egg white, such as ovalbumin, but can also be caused by proteins in the egg yolk, such as apovitillin. Versions of these proteins can be found in the eggs of many bird (chicken, duck, quail, turkey and ostrich, for example)and fish species, though the cross-reaction of fish roe with bird’s egg allergens is rare.

Aside from egg-containing foods, individuals allergic to chicken eggs should also be cautious of flu vaccines as chicken eggs are used in the production of flu vaccine. Otherwise, for egg consumers, reconsidering the source of our egg products may be of interest. A recent report published in the Journal of Holistic Nursing Practice in 2010 found that factory farmed egg consumption is linked to increased salmonella poisoning compared to cage-free eggs.

Food Allergy Research and Education
Current Allergy and Asthma Reports
Pediatric Clinics of North America
European Journal of Allergy and Clinical Immunology
The Canadian Society of Allergy and Clinical Immunology
Holistic Nursing Practice


Peanuts are members of the legume (bean) family of plants and are commonly found in baked goods, cooking oils, sauces and Eastern cuisines. Approximately 2.1% of American children and 0.6% American adults suffer from peanut allergies and similar rates of peanut allergy are seen in other westernized countries (Canada, United Kingdom, Australia). Unfortunately, peanut allergies cause the most cases of anaphylaxis out of all of the allergens, and since the prevalence of peanut allergies in children has increased nearly four-fold (0.6% to 2.1%; U.S.) in the past decade, the increased risk of death in children has become a pressing concern.

In response to the increase in peanut allergies, many scientists have begun to engineer peanut plants that are hypoallergenic by selectively removing the genes responsible for producing peanut allergens. These new strains of peanuts would theoretically be safe to eat, and would produce no allergic reactions. Though that may be the primary concern for those with peanut allergies, peanut crops may also be harmful to non-allergic individuals as they are often rotated in fields that grow cotton. These cotton fields are often sprayed with herbicides (linked to various health conditions) that can still be present in the soil when the crops are rotated.

Food Allergy Research and Education
Current Opinion in Immunology
Discovery Medicine
Journal of Agricultural and Food Chemistry
Peanut Rotation Study
Critical Reviews in Food Science and Nutrition


Tree nuts are dry fruits that contain one seed and a hard outer wall, such as almonds, cashews and pecans. These nuts are primarily used in baked goods, desserts, cereals, and Eastern cuisines. The majority of tree nut allergies (affecting 0.2% of North American children and 0.5% of adults) are caused by certain proteins that are common across many types of tree nuts. Due to this, many of those with tree nut allergies are allergic to more than one type of tree nut.

Tree nut and peanut allergies often go hand-in-hand, with many sufferers bearing both types of allergies. Therefore, those suffering with any type of tree nut allergy should be cautious when purchasing packaged foods as cross-contamination can occur in food processing plants that handle tree nuts, peanuts or both.

Food Allergy Research and Education
Current Allergy and Asthma Reports
The Journal of Nutrition

TellSpec Top 5: The metals in your food

Last week we introduced Top 5 Metals in Your Food. Here is another group of 5 metals for your curiosity.

6.Mg6. Manganese is essential to human health and plays many roles, including aiding brain and nerve function, blood sugar regulation, and bone and connective tissue health. Manganese poisoning is uncommon outside of industries that deal directly with it, though early exposure is associated with delayed neurodevelopment. Manganese deficiency, however, is estimated to occur in up to 37% of Americans, particularly those with refined-grain-based diets, as it is found in whole grains, nuts, and seeds. Manganese may help minimize osteoporosis damage when taken with other essential elements; may reduce PMS symptoms; may improve cholesterol profiles in diabetics; and may help reduce pain in arthritic patients.

References: University of Maryland Medical Center / Food Standards Agency

7.Hg7. Mercury is most commonly discussed regarding methylmercury content in seafood. Methylmercury will accumulate within the protein of fish and shellfish and is not destroyed by cooking; other sources include rice grown in mercury-contaminated areas and sometimes organ meats. As methylmercury accumulates up the food chain, choosing smaller fish lower on the food chain like sardines, not only larger predatory fish like tuna, can help control intake. Some studies have also found mercury in high fructose corn syrup. Methylmercury intake is associated with cardiovascular disorders; possible effects on male fetuses during pregnancy; and neurological disorders and delayed development, notably in children whose mothers’ diet had higher mercury levels.

References: BioOne / International Journal of Environmental Research and Public Health / European Commission 1 / European Commission 2

8.Se8. Selenium is essential to human health and typically intake is within the healthy range. However, exceeding the maximum recommended intake can lead to symptoms within days. These symptoms include hair and nail loss, skin lesions, digestive issues, and effects on the nervous system. Fish, shellfish, and animal meats can provide the recommended daily intake within one to two servings; multiple servings over the day can get the intake up into the danger zone, particularly when combined with supplements such as multivitamins. Perhaps the biggest risk is brazil nuts, an ounce of which can contain over 700% of the recommended daily intake—well above the maximum intake value. So stick to nuts like almonds for your afternoon snack.

References: ScienceDirect 1 / ScienceDirect 2 / De Gruyter / ScienceDirect / Nutrition Data / Live Science

9.Sn9. Tin is nonessential to life and fortunately is not highly absorbed by the body. High levels of tin intake can cause nausea, vomiting, and diarrhea. The most likely source of tin in the diet is unlacquered tin cans and possibly tin-containing cooking implements. Tin leaching from tin cans is most common if acidic foods are stored in them; buying tomato products, fruits, pickles, and similar items in glass containers reduces this risk. Tin-containing-compounds known as organotin compounds have been used industrially and agriculturally, and therefore may exist in water runoff and marine life.

References: Wiley Online Library / ScienceDirect

10.Zn10. Zinc is essential to a healthy body and deficiency is more common than excess consumption. Zinc deficiency can cause impaired cognitive and motor function, is associated with certain cancers, increased risk of pneumonia, complications to pregnancy, and can impact appetite. Risk of zinc deficiency increases with gastrointestinal illnesses causing malabsorption, diabetes, and bariatric surgeries. Food sources of zinc include oysters, shellfish, meat, legumes, and nuts (notably cashews and almonds.)

References: NCBI / National Institutes of Health / Food Navigator / Food Standards Agency / Healthy Eating

Tellspec Top 5: The metals in your food

Today’s Top 5 from TellSpec is shedding light on the topic of metals in your food. What they are, where they come from, and what effects they may have on your health.

First, let’s clear up terms you may have heard:
Heavy metals refers to elements (the things that make up all of life as we know it) that have metallic properties. Heavy metals are not inherently bad; some, like zinc and copper are essential to life; but others, like mercury and lead are considered toxic metals, as significant levels can cause serious illness. However even essential metallic elements can be toxic at a high enough intake.

Alkaline metals refers simply to the group of alkaline earth metals of the periodic table, including calcium. These are distinct from the terms alkali and acidic, which are common in diet discussion.

Alkalinity in that context refers to the pH scale, where something is rated as more acidic or more alkaline (basic); think vinegar and baking soda. So “alkaline foods” or even “alkalized” foods, such as alkalized, Dutch process cocoa, do not necessarily contain significant levels of the alkaline metals.

Elements, minerals, and metals. These terms are overlapping and dependent on context or even quantity. For example copper: copper is a metal in the broad sense, it is also listed as a mineral on nutrition facts labels, and it is an element on the chemist’s periodic table.

The Top 5:

1.Al1. Aluminium has no known use within the body, and its main sources within the diet come from trace amounts in food, water, and transfer from aluminium foil and cooking tools. Acidic foods increase the amount of the metal that will leach from contact with aluminium pots, pans, foil, and utensils. Though no conclusive link has been proven, at the intake expected from a typical diet, studies have suggested a link between aluminium and disorders of the brain, including Alzheimer’s, dementia, and hyperactivity. Fortunately aluminium is not very readily absorbed by the body, however older individuals may be more susceptible to aluminium absorption and its effects.

References: Food Standards Agency 1 / Food Standards Agency 2 / Environmental Science Europe / NRC Research Press / Sage / Food Standards Agency 3

2.As_V22. Arsenic may or may not be essential to life, though it is certainly toxic at significant levels. Low level and chronic exposure to arsenic can cause nausea, vomiting, and cardiovascular issues, and is associated with increased cancer risk, lung damage, and possible problems in pregnancy and brain development. Sources of arsenic include pesticides, seafood, possibly fruit juices, and rice. Notably, brown rice will typically contain more arsenic relative to its polished white rice counterpart, as arsenic accumulates within the portion of the grain that is removed to form white rice.

References: NCBI / Journal of Nutrition / Food Standards Agency / European Commission / WebMD

3.Cd3. Cadmium has not been shown to be essential to human health, and its main sources are cigarettes, industrial pollution, and some foodstuffs. Seafood and organ meats have relatively high levels of cadmium, though grains and cereals as well as fruits and vegetables are a source, particularly as they are more common in the diet. Cadmium intake is generally quite low (though low iron increases its uptake), however it does not leave the body quickly and therefore can cause damage later in life. Cadmium is particularly toxic to kidney function, can cause reduced bone density, and is associated with increased cancer risk.

References: Wiley / Science Direct / Dart Mouth / Food Standards Agency / European Commission / EFSA

4.Cu4. Copper is essential to human life, and adequate levels are usually attainable with a healthy diet. Sources include seafood, organ meats, nuts, and legumes. Copper toxicity may be a risk if you make use of unlined, or worn-down, copper cooking implements, particularly if they maintain contact with acidic foods. Exercise caution with copper bowls and pots that have been used for awhile, or come from yard sales. Copper poisoning can cause vomiting, low blood pressure, and gastrointestinal issues; long-term exposure can damage liver and kidneys. High levels of copper within the body is associated with Alzheimer’s disease, though a causal link is not yet confirmed.

References: Food Standards Agency / Clinph Journal / Retinning / Food Science / SF Gate

5.Pb5. Lead is a well-known toxic metal, with significant negative health effects with acute and chronic exposure. Long-term effects are particularly concerning as lead takes between months and years to leave the body, during which time it can damage virtually every system in the body, particularly the brain. This is especially concerning for pregnant women, as lead stored in the bones during earlier exposure may be freed during pregnancy and breastfeeding, and can transfer to the baby in-utero or through breast milk, damaging the developing brain. Outside of environmental (air, dirt, dust), occupational, and incidental exposure (lead-containing paints, ceramics, and crystalware), food is a source of lead. Meat and organ meat have the highest levels, but trace amounts can be found in grains, dairy, and even fruits and vegetables. While lead is highly monitored, consumers should make informed decisions when incorporating certain items in their diet.

References: Health Canada / EFSA / Food Navigator / Food Standards / European Commission