Dear Dr. Dave and Dr. Dee,
I eat microwave popcorn at least three times a week, maybe more depending if we are renting a movie over the weekend. Normally, I don't bring microwave popcorn to work, but I decided to bring in some leftovers yesterday. My coworker said that microwave popcorn is bad for me because of the artificial butter flavoring. This was the first time that I had heard of this. I cannot imagine not having my popcorn. Do I need to stop eating popcorn?
Dear Popcorn addict,
The butter flavoring in microwave popcorn, diacetyl, is associated with lung damage in factory workers and research suggests diacetyl could increase an abnormal brain protein involved in Alzheimers disease.
Because diacetyl was linked to severe lung disease in employees at microwave popcorn and food-flavoring factories, several microwave popcorn manufacturing companies have stopped using diacetyl and are instead using a substitute. Seattle PI journalist, Andrers Schneider, reported that over 500 workers or their families had filed lawsuits because of injury or death from diacetyl exposure (Schneider, A., "Additive found in more than 6,000 products," Seattle P-I, Dec 20, 2007).
The U.S. Dept of Agriculture does not require that diacetyl be named on the product nutrition or ingredient list, only that it be listed under the general term, artificial flavors or artificial flavorings. Also, keep in mind that the diacetyl substitute butter flavorings have not yet been proven to be any safer for use. Diacetyl substitutes are structurally related to diacetyl and there are concerns about the adverse health outcomes of these alternatives ("Food Standards and Labeling Policy Book ," USDA Food Safety and Inspection Service, fsis.usda.gov, Aug 2005; "Diacetyl and Substitutes," U.S. Department of Labor OSHA, 2010; "Occupational Exposure to Flavoring Substances: Health Effects and Hazard Control," U.S. Dep of Labor OSHA, 10-14-10).
POPCORN IS HEALTHY
You do not need to stop eating popcorn. To avoid diacetyl or diacetyl substitutes, it would be best to pop your own, or buy organic microwave popcorn without butter flavoring.
Unbuttered, unsalted popcorn is a very healthy snack with lots of fiber, low in calories (3 cups has 93 calories and 1.1g of fat), and high in antioxidants (nearly twice as much polyphenol as a serving of fruit or vegetables). In fact, popcorn "may be the perfect snack food. It's the only snack that is 100 percent unprocessed whole grain," says Joe Vinson, Ph.D., professor of Chemistry at the University of Scranton ("Popcorn: The snack with even higher antioxidants levels than fruits and vegetables," American Chemical Society 243rd Meeting, Press Room, March 25, 2012).
DIACETYL BUTTER FLAVORING CONTROVERSIES
1. SEVERE LUNG DISEASE
Diacetyl has been associated with severe lung damage called bronchiolitis obliterans, also known as popcorn lung disease because workers at microwave popcorn factories were affected from inhaling vapors. Since August 2000, the U.S. Department of Health and Human Services NIOSH (National Institute for Occupational Safety and Health) has investigated diacetyl and lung disease in popcorn manufacturing workers and has issued safety advice for exposure limits and precautions for working with diacetyl and pentanedione, which is another butter flavoring used as a diacetyl substitute. Hazard guidance for diacetyl, however, is only advisory and does not create legal obligations ("Occupational Exposure to Diacetyl and 2,3-Pentanedione," Department of Health and Human Services National Institute for Occupational Safety and Health, August 12, 2011; "Hazard Communication Guidance for Diacetyl and Food Flavorings containing Diacetyl," Department of Health and Human Services National Institute for Occupational Safety and Health, 2012).
Consumers should also use caution when cooking with butter flavorings as they may be hazardous when heated and inhaled. Researchers Rigler & Longo heated natural butters and artificial microwave popcorn butter flavorings (powder, pastes, and liquid) and found "microwave butter flavoring products generate concentrations of diacetyl in the air great enough to endanger those exposed" (Rigler, M.W. & Longo, W.E., "Emission of diacetyl (2,3 butanedione) from natural butter, microwave popcorn butter flavor powder, paste, and liquid products,"Int J Occup Environ Health, 2010 Jul-Sep;16(3):291-302).
2. ABNORMAL BRAIN PROTEIN - ALZHEIMERS DISEASE PROCESS
Questions about diacetyl and neurologic toxicity have also been raised. Researchers More,Vartak and Vince tested diacetyl in the lab using concentrations typically found in the workplace and found diacetyl accelerated the aggregation of the abnormal brain protein called beta amyloid, which is associated with Alzheimer's disease. In addition, diacetyl easily passed through the researcher's in-vitro "blood-brain barrier" that protects the brain and also inhibited a protective protein from clearing beta amyloid from the brain (More, S.S., Vartak, A.P., and Vince, R., "The Butter Flavorant, Diacetyl, Exacerbates â-Amyloid Cytotoxicity," Chem. Res. Toxicol. July 2012).
"Whether toxic levels of diacetyl are achieved in various body compartments upon mere (over) consumption of diacetyl-containing food substances is an unanswered but an important question," noted the researchers ((DeNoon, D.J., "Buttered Popcorn Flavoring Linked to Alzheimer's: Diacetyl in Butter Flavoring, Beverages May Build Brain Plaque," WebMD.com Alzheimer's Disease Health Center, Aug 8, 2012).
DIACETYL - WHERE IS IT FOUND
Diacetyl is found naturally in low concentrations in products such as butter, fruits, flowers, and as a byproduct of fermentation in beer, and is an added synthetic chemical in a wide variety of items from margarine to pet food to floral fragrances and mosquito repellent. Diacetyl is also in the air from exhaust emissions, cigarette smoke, livestock waste, and moldy buildings ("Chemical Information Review Document for Artificial Butter Flavoring and Constituents Diacetyl [CAS No. 431-03-8] and Acetoin [CAS No. 513-86-0]," Integrated Laboratory Systems, January 2007; Turner, S. L., Li, N., Guda, T., Githure, J., Carde, R.T., Ray, A., "Ultra-prolonged activiatino of CO2- sensing neurons disorients mosquitoes," Nature, 2011 June 2; 474(7349): 87-91).
The amount of diacetyl is minimal in natural occuring foods such as butter. For example, natural butter contains 7,500 times less diacetyl compared to pastes and liquid butter flavors which contain 6% to 10.6% diacetyl (Rigler, M.W. & Longo, W.E., "Emission of diacetyl (2,3 butanedione) from natural butter, microwave popcorn butter flavor powder, paste, and liquid products,"Int J Occup Environ Health, 2010 Jul-Sep;16(3):291-302).
However, only salted butter does not have diacetyl added to it. Unsalted butter and sweet butter have diacetyl added because "if you don’t salt it, you have to add something to keep it from spoiling, and lactic acid and diacetyl is a way of stabilizing it" (Schneider, A., "Diacetyl shows up in more foods, puts commerical and home cooks at risk," Seattle P-I, December 22, 2007).
FOOD PRODUCTS WITH DIACETYL
Seattle P-I reporter Andrew Schneider interviewed food scientists who estimated that diacetyl butter flavoring is used in more than 6,000 products. (Schneider, A., "Additive found in more than 6,000 products," Seattle P-I, Dec 20, 2007)
The U.S. Occupational Safety & Health Administration (www.osha.gov) lists the following products with diacetyl:
1. NATURAL: Diacetyl naturally occurs in butter, milk products, yogurt, grains, meat, wines, beer, oils of pine, oil of angelica, oils of lavender and other flowers, many flowers, raspberries, strawberries, citrus, ligonberry, guava, cabbage, peas, tomato, vinegar, cheeses, chicken, beef, mutton, pork, cognac, whiskies, tea, and coffee.
2. ADDED FLAVORING: Diacetyl is used in manufacturing as a flavoring in alcoholic beverages, baked goods, cheese, chewing gum, fats and oils, frozen dairy products, gelatins and puddings, gravies, hard candy, soft candy, imitation dairy, meat products, milk products, nonalcoholic beverages, and snack foods.
The percentage of diacetyl in a product varies, with microwave popcorn having the highest proportion of diacetyl varying from 1-25%, compared with confectionary up to 1% and marshmallows up to 5% ("Occupational Exposure to Diacetyl and 2,3-Pentanedione," Department of Health and Human Services National Institute for Occupational Safety and Health, August 12, 2011).
Average diacetyl in beer is .05 mg/L, although British ales can contain 0.30/mg/L, and some stouts have 0.60 mg/L (Fix, G.J., "Diacetyl: Formation, Reduction, and Control," Brewing Techniques, July/August 1993).
The amount of diacetyl in wines such as Chardonnay ranged from 0.005 - 1.7 mg/L. (Martineau, B., Henick-Kling, T., Acree, T., "Reassessment of the Influence of Malolactic Fermentation on the Concentration of Diacetyl in Wines," Am Soc Enol Vitic 46 (3): 385–8, 1995).
HARMFUL CONCENTRATIONS OF DIACETYL
Diacetyl can evaporate in the air in liquid or solid form, and heat can increase the amount of diacetyl in the air, measured in ppm (parts per million). Breathing concentrations of diacetyl in the air can affect the respiratory system by irritation (> 30 ppm) or damage (>190 ppm) (Kreiss, K., "Flavoring-related bronchiolitis obliterans," Curr Opin Allergy Clin Immunol 7:162–167).
Affected workers at five plants had average airborne concentration of diacetyl in factory mixing areas ranging from 0.02 to 37.8 ppm. "But real-time monitoring in a worker's breathing zone revealed peak levels of 80 ppm during a process where liquid butter flavor was poured into heated mixing tanks" ("Occupational Exposure to Flavoring Substances: Health Effects and Hazard Control," U.S. Dep of Labor OSHA, 10-14-10).
In laboratory experiments, rats died when exposed to 200 - 400 ppm diacetyl in the air for 6 hours for 5 days ("Hazard Communication Guidance for Diacetyl and Food Flavoriings Containing Diacetyl," U.S. Dept of Labor OSHA, 2012).
POPULAR COOKING BRANDS WITH DIACETYL
The Seattle P-I tested 22 different brands of popular butter flavored cooking products to see how much diacetyl was released into the air from being heated in skillets. The concentration of diacetly was measured in ppm and resulted in the following, ranked lowest to highest (Schneider, A., "Flavoring additive puts professional cooks at risk," seattlepi.com, Dec 20, 2007).
1. BASELINE: Two real butters (both sweet butters where diacetyl added): 7 - 16 ppm.
2. Butter-flavored cooking spray: > 164 ppm
3. Margarine and shortening products: 7 - 180 ppm
4. Butter-flavored cooking oils used by professional cooks: 23 - 234 ppm
5. Oil for popping corn: 1,062 - 1,125 ppm
ORAL ADMINSTRATION OF DIACETYL STUDY
Rats fed daily oral administration of diacetyl ranging from 10-540 mg/kg for 90 days decreased in weight, increased white blood cell count, became anemic, increased water consumption, had necrosis in the stomach, and increased weights of the liver, kidney, adrenal gland, and pituitary gland ("Chemical Information Review Document for Artificial Butter Flavoring and Constituents Diacetyl [CAS No. 431-03-8] and Acetoin [CAS No. 513-86-0]," Prepared by Integrated Laboratory Systems, January 2007).
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