Born in the early years of the 20th century, my maternal grandparents were reared on farms in the Midwest. Their families raised hogs, chickens, and dairy cows for meat, eggs, and milk products. They grew their fruits and vegetables in orchards and gardens. They cured their meat, canned their produce, and baked their own bread. Other than staples such as flour, sugar, salt, and spices, there was little in my grandparents’ diets that did not originate on the farm. Consequently, there was never any question as to what was in their food unless a relative or neighbor shared a cake made from a secret recipe.

When my grandparents became adults, they left the farms and moved to the city. My family members have been city-dwellers ever since. Like our fellow urbanites, we obtain our foodstuffs from a grocery store rather than from our back yard. We have become so far removed from the source of our food that when I offered to teach my daughter how to cut a raw, whole chicken into serving pieces, she refused, saying, “I don’t mind eating chicken, but I don’t want to be reminded of what anything I eat looked like when it was alive.” Even more revealing was the response of her friend, then in high school, when I began an explanation on how to cook and bone a chicken. In total surprise, the friend exclaimed, “Chickens come with bones? I thought you could only buy them boneless and skinless!”

Being totally divorced from the production of our food is not inherently evil. However, it can be dangerous for people with food allergies or intolerances. As many have learned, what they don’t know can hurt them if it is in their food. In order to help consumers identify ingredients that may trigger immune responses, Congress passed the Food Allergen Labeling and Consumer Protection Act (FALCPA) in 2004 requiring manufacturers to clearly identify on their labels ingredients containing proteins from any of the eight most common allergens. The same amendment required that by August 2008, the Secretary of Health and Human Services would issue a definition and rule for labeling products as “gluten-free.” In response, the Food and Drug Administration (FDA) proposed a definition that included, among other things, a quantitative measurement: for a food to be labeled “gluten-free,” it must contain less than 20 parts per million (ppm) gluten.

“Less than 20 ppm gluten” sounds impressive as a standard, but what it means in terms of practical quantities may be unclear to many consumers. At the most obvious level, the requirement states that in a quantity of one million parts, less than 20 of the parts may be gluten; the remaining 999,980+ parts must be non-gluten. Measured by volume, 130 cups of a product would contain less than 1⁄8 teaspoon of gluten. In units of weight, 312 pounds of a food would contain less than 1⁄10 ounce of gluten. While it may seem absurd to require manufacturers to monitor such a miniscule amount of gluten, it is not uncommon in our society to regulate even smaller quantities of contaminants. The Environmental Protection Agency has a tolerance limit of 0.5 ppm for the amount of Diazinon insecticide residue on almonds and apples. National Primary Drinking Water Regulations require public water systems to take action if they determine that the tap water delivered to consumers contains as little copper as 1.3 ppm and as little lead as 15 ppb, i.e. 15 parts per billion. Minute amounts of substances can have a significant impact on health.

Though the 20 ppm rule sets an upper limit for gluten contained in a food labeled “gluten-free,” the value is expressed as a ratio, not as a weight or volume per serving. The specific quantity of gluten that a person could conceivably ingest from eating a food would depend not only on the actual (rather than allowed) amount of gluten in it but also on the size of the serving. For example, if a slice of gluten-free bread weighed 38 grams, it would contain less than 0.76 milligrams (mg) of gluten. During the course of a day, if a person ate a bowl of cereal, a slice of toast, a hamburger bun, a serving of chips, a dinner roll, and a couple of cookies, he would be consuming approximately 280 grams of food products potentially containing a total of nearly 5.6 mg of gluten even if each food item fell within the FDA proposed guidelines.

This naturally brings up the question, “How much trace gluten can a celiac safely consume in one day?” Unfortunately, a safe threshold for gluten exposure has not been established yet. A research trial published in the American Journal of Clinical Nutrition in January 2007 found that although some study participants did not show intestinal change after being challenged with 50 mg of gluten daily over a period of 90 days, other subjects showed intestinal damage from ingesting only 10 mg of gluten daily. The researchers noted that there was a wide variation in patient sensitivity to trace amounts of gluten and offered this conclusion, “The ingestion of contaminating gluten should be kept lower than 50 mg⁄[day] in the treatment of CD.”

Congress passed the FALCPA with its accompanying mandate to define gluten-free labeling in order to make it easier for celiacs to choose foods that would be in compliance with a gluten-free diet. An established standard would assure consumers that specific qualifications had been met for the label to have been applied. The intent was not that celiacs would have to sit down to every meal with a calculator included in the place setting. On the other hand, consumers will need to be aware that foods labeled “gluten-free” will not necessarily contain zero gluten. Rather, if they contain gluten at all, the amount will be a trace level below 20 ppm. Very sensitive celiacs who are concerned about ingesting even minute amounts of gluten will want to continue focusing their diet on fresh produce and minimally processed foods. And perhaps they will want to check the batteries in their calculators.

Mini-Tip: How to do the calculation

20 parts per million (ppm) is the same as 20 milligrams per kilogram (20 mg⁄kg). If a serving size on a label is expressed in grams, the potential amount of gluten in a single serving can be calculated by multiplying the number of grams in one serving of product times 20 and multiplying the result by 1⁄1000 (grams /kilograms conversion ratio):

(Serving size in grams) x (20 mg⁄kg) x (1⁄1000 kg⁄g).

The end result will be in milligrams. It is important to note that the food product must contain less milligrams of gluten than the calculated value for the product to comply with the FDA guideline.

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