Nickel Allergy
Nickel is a well-known cause of contact dermatitis in nickel-sensitive people, inducing a reaction wherever it is in close contact with the skin or mucous membrane. This response is known as a cell-mediated immune reaction (Type IV hypersensitivity reaction). The nickel induces local T-cell lymphocytes to produce cytotoxic cytokines that cause the itching, reddening, and scaling of contact dermatitis.
Food allergy caused by nickel was first suspected when dermatologists noticed that some people showed symptoms of dermatitis on skin surfaces that were not in contact with any known allergen. These dermatologists suspected that the allergenic source might be in something ingested and looked for sources of known contact allergens, such as nickel, in commonly eaten foods. They noticed that sometimes the nickel in food is not a natural component but instead is introduced during processing, for example, from metal containers or from cooking and processing utensils.
This chapter will provide you with the information you need to avoid the major sources of nickel in your diet if you, or your doctor, suspect that nickel allergy may be contributing to your skin rash or dermatitis.
Management of Nickel Allergy
Clinical studies suggest that some nickel-sensitive people benefit from avoiding food sources of nickel. However, opinions differ on what constitutes a nickel-restricted diet. In one research study, an oral dose of nickel (as nickel sulfate) as low as 0.6 mg produced a positive reaction in some nickel-sensitive persons.
However, another report indicated that 2.5 nig was required to induce a flare-up. Because the levels of nickel required to induce a reaction have varied widely in different studies, it is difficult to determine a “safe level” of dietary nickel for nickel-sensitive persons.
To further confuse the subject, the level of nickel in foods varies with the plant species and with the nickel content of the soil in which the plant was grown or, in the case of seafood, of the aquatic environment1. Processing of foods can increase the level of nickel in a food product as well. For example, minute traces of nickel from metal grinders used in milling flour can increase the level of nickel in flour considerably, and stainless steel cookware will increase the level of nickel in the food cooked in it.
Often dietary nickel is not the sole cause of the dermatitis, however. In these cases, nickel avoidance may improve the situation but does not make the symptoms disappear.
Human beings require a minute amount of dietary nickel for essential metabolic processes. For adults, the U.S. RDA (Recommended Dietary Allowance) for nickel is 50 µg daily. (The Canadian Dietary Standard does not include a recommendation for nickel.) The richest sources of dietary nickel are nuts, dried peas and beans, whole grains, and chocolate.
The Relationship Between Nickel and Iron
Most ingested nickel remains unabsorbed and is excreted in the feces. Usually less than 10% of the nickel in food is absorbed, but this amount increases in iron-deficient persons and lactating mothers. Nickel and iron use the same transport system to cross from the intestine into circulation, so, if iron is being transported, nickel is excluded. Accordingly, people who are sensitive to nickel should include iron-rich foods in their diet.
Nickel Contact Dermatitis and Oral Tolerance
The most common cause of nickel dermatitis is direct contact with nickel-containing objects. People who have tested positive for nickel using a patch test (on skin of the forearm or back) should avoid contact with all objects containing the metal. A recent study indicated that the severity of contact dermatitis related to nickel can be reduced by oral exposure to nickel, for example, in the form of a dental appliance. According to other studies, oral exposure to nickel can worsen established nickel contact dermatitis initially, but prolonged exposure can reduce the clinical symptoms.
The subject of nickel contact dermatitis, nickel allergy, and achievement of tolerance is confusing from a practical point of view because of the extremely complex series of events that occur in the immune system. Nickel contact dermatitis is caused by a Type IV hypersensitivity reaction; nickel allergy is possibly a Type I hypersensitivity; and the precise mechanism that allows the immune system to achieve tolerance, especially to foods, is unclear at present. Nail polish with a metal mixing ball in the container should be avoided; the solvents in the polish can leach out the nickel.
The site of the reactions will be a good indicator of the source of the nickel.
Causes of Nickel Contact Dermatitis
The most common cause of nickel dermatitis is direct contact with nickel-containing objects. Some frequent causes of nickel contact dermatitis include
| Jewelry | Thimbles |
| Coins | Needles |
| Detergents | Pins |
| Keys | Wire supports in bras |
| Buckles | Hairpins, curlers, bobby pins |
| Clasps | Eyeglass frames |
| Zippers | Paper clips |
| Snap fasteners | Staples |
| Hook-and-eye fasteners | Metal pens and clips |
| Dental instruments | Stainless steel cutlery |
| Door handles | Metal objects held in mouth |
| Knitting needles | Medals |
| Metal shoe eyelets | Safety pins |
| Bullets | Screws, etc., in orthopedic devices |
| Metal pots and pans |
The Nickel-Restricted Diet
People suspected of having an allergy to nickel that is caused by eating foods that contain the metal often try a nickel-restricted diet for a limited period of time. Usually 4 to 6 weeks is sufficient to determine the effectiveness of the diet. Table The nickel-restricted diet provides the nickel-restricted diet.
Table The nickel-restricted diet
| Food Category | Low Nickel Content
(Foods Allowed) |
High Nickel Content
(Foods Restricted) |
| Milk andMilk Products | All, including
• Milk • Butter • Margarine • Yogurt • Cheese |
• None |
| Breads and
Cereals |
All not on “high nickel” list,
including • Rice • Corn • Popcorn • Rye • Wheat bread in moderation • Pasta in moderation |
• Oats
• Oatmeal • Buckwheat • Wheat germ • Wheat bran • Multigrain bread • Multigrain cereals |
| Vegetables | All not on “high nickel” list | • Beans (fresh and frozen)
• Spinach • Green peas • Kale • Asparagus • Broccoli |
| Legumes,
Dried Peas, and Beans |
• None | All, including
• Lentils • Yellow split peas • Chickpeas • Beans — brown, white, and green • Soybeans • Soybean products • Soy flour • Bean sprouts |
| Fruit | All not on “high nickel” list | • Pear
• Banana • Pineapple • Plum • Prune • Raspberry • Fig |
| Meat, Poultry,
Egg |
• Egg
• Chicken • Turkey • Other poultry • Meat from all species |
• None |
| Fish | Fish, including
• All fin fish |
All shellfish,
including • Shrimp • Prawn • Oysters |
| Nuts and Seeds | • None | • Mussels
All nuts, including • Peanut • Walnut • Almond • Hazelnut • Alfalfa seed • Flaxseed • Poppy seed • Sunflower seed |
| Beverages | • Coffee
• Soft drinks • All fruit juices except those on “high nickel” list • Alcoholic beverages |
• Tea
• Cocoa • Chocolate drinks • Pineapple juice • Prune juice • Raspberry juice • Pear Juice • (All other juices are low in nickel) |
| Sweets and
Confectioneries |
All not on “high nickel” list,
including • White sugar • Brown sugar • Honey |
• Chocolate
• Licorice • Almond paste (marzipan) • Any candy bars containing nuts or seeds |
| Herbs and Spices | • All in moderation | • None |
| Flavorings | • All in moderation including yeast-containing breads andmustard | • None |
| Other | • Vitamin and mineralsupplements without nickel | • Vitamin and mineral supplementswith nickel
• Commercial baking powder |
The table is based on a compilation of data from several different sources. It is not possible to provide a reliable scale of the level of nickel in foods, because levels of the metal vary in foods for a number of reasons, including
♦ The species or variety of plant from which the food was derived.
♦ The amount of nickel in the soil in which the plant was grown.
♦ In the case of fish, the amount of nickel in the water from which the fish was harvested.
♦ In the case of flours, how much nickel was introduced into the flour during the process of milling with metal grinders. Stone-grinding of flours avoids this source of the metal, but nickel is present to varying levels in the grain itself, depending on the species and the content of nickel in the soil in which it was grown.
Nutrients
The nickel-free diet offers a good variety of foods in all food groups, and basic nutrient needs should be easily met. However, two nutrients worthy of special consideration are iron and fiber.
Iron
Excellent sources of easily absorbed iron (heme iron from animal sources) are liver, beef, turkey (dark meat), eggs, lamb, pork, and baked salmon. Good sources of nonheme (from plant sources) iron are blackstrap molasses, dried apricots, cooked beet greens, green peas, and dates.
Foods rich in vitamin C such as citrus fruit, tomatoes, and peppers help increase iron absorption. Iron absorption is also increased if you avoid coffee with meals and for one hour after meals.
Fiber
With the restriction of wheat bran, oats, some vegetables and fruits, legumes, nuts, and seeds, many of the commonly used high-fiber foods are restricted. Some alternative choices include:
♦ Grains: brown and wild rice, corn and popcorn, corn bran, cereal, rye bread, crackers
♦ Vegetables: Brussels sprouts, corn, parsnips, carrot, eggplant, winter squash, sweet potato, yams
♦ Fruits: blackberries, dates, raisins, blueberries, boysenberries, crabapple, cranberries, currants (red and white), kiwi fruit, lemon, lime, orange, rhubarb
Substitutes for Other Nickel-Containing Foods
Soups
Some dried, packaged soup powders appear to be high in nickel. Better choices include homemade stocks from allowed vegetables plus meat; stocks from defatted meat drippings with tomato or vegetable juice or milk.
Desserts
All desserts and baked goods made without chocolate, oats, nuts, seeds, and fruits on the “high nickel” list are allowed. Also, try angel food cake instead of chocolate cake and gingersnaps or tea biscuits instead of chocolate chip cookies. Vanilla, butterscotch, and caramel ice cream (check ingredients) are allowed.
Condiments and Snacks
♦ Salt and pepper, and all herbs and spices, are allowed.
♦ Tabasco and Worcestershire sauce are fine, but avoid any soy-based sauces.
♦ Ketchup, mustard, relish, pickles, and salsa are allowed.
♦ Popcorn, potato, corn, and tortilla chips are good choices for snacks.
♦ Eat hard (mints) and gelatin candies instead of chocolates.
Cooking
Enamel-coated pans, pans with nonstick coating, or glass or microwave-safe plastic containers should be used. Stainless steel cookware and contact with chromium-plated utensils should be avoided.
This post has been viewed 608 times.