Potato Chips: The Inside Crunch

Potato Chips: The Inside Crunch
History credits George Crum with creating the first potato chip in 1853 while working as a chef in an upstate New York restaurant. A dining patron, the story goes, repeatedly demanded a thinner french fry, so George obliged by slicing ridiculously thin potatoes. The customer loved the crispy and crunchy fried potatoes and soon they were a local favorite. It wasn’t until the 1920s, however, did Herman Lay (using the recently invented mechanical potato peeler) establish a national market for potato chips. George Crum had no idea that his discovery would become the best-selling snack chip in America, nor could he have imagined that potato chips would one day be cited as a health risk.

Until just a few years ago, potato chips were maligned only for being a high calorie snack. We know now that the types of fats used in the frying process make a real difference and that frying potatoes creates a toxic substance called acrylamide. While there is agreement (for the most part) regarding the healthiest oils, there are many unanswered questions about acrylamide.

Trans Fats (partially hydrogenated oil)
When I was in graduate school in 1996, I wrote a letter to the FDA urging that foods containing harmful trans fats be labeled as such. Apparently my letter was misplaced and just arrived last year, as the FDA is finally addressing this long-standing problem. By January 1, 2006, all food manufacturers must indicate the trans fat content of their product in the Nutrition Facts section of the label. Be forewarned, however, that the law allows companies to label their food as being trans fat free if it contains less than 0.5 grams of trans fat per serving. Take a close look at the serving size of your favorite snack foods. To avoid trans fats, avoid products that contain partially hydrogenated oil in the ingredient list (commercially baked sweets, processed foods, fast-food french fries and other fried foods, and margarines). Many producers have replaced partially hydrogenated oils with refined oils (like low-quality tropical oils, cottonseed oil, and soybean oil) that are not much healthier. Fortunately, there are potato chip manufacturers who have replaced partially hydrogenated oils with higher quality oils (see Hippie Wisdom, below).

Acrylamide has been used by industry to make a non-toxic substance called polyacrylamide since the 1950s. Polyacrylamide is used to purify drinking water and is found in some food packaging materials, soil conditioning agents, and plastics. In each application, some of the original acrylamide remains in the finished product in very small quantities. Because acrylamide is classified as “probably carcinogenic to humans” and damaging to the nervous system, the FDA and EPA have established “acceptable levels” of acrylamide in drinking water and other products. 

In 2002, new evidence was announced that created quite a stir. A Swiss team of researchers found significant levels of acrylamide in a wide range of foods, from potato chips to toast. It has since been confirmed that cooking carbohydrates at high temperatures higher than 250 degrees Fahrenheit - creates acrylamide and that concentrations increase with cooking time. For the chemists out there, high temperatures cause the glucose in carbohydrate foods to binds with the amino acid asparagine to form acrylamide. Researchers know that acrylamide damages DNA and cell proteins and may lead to mutations that cause tumors. While high doses have caused cancer in animal studies, there is no solid evidence to date of acrylamide-related cancer in humans. The question is, how much acrylamide in foods is too much?

The California-based Environmental Law Foundation (ELF) strongly believes that current levels are too high. ELF plans to sue potato manufacturers on the issue that consumers are entitled to warning labels as passed into law by California Proposition 65 (Safe Drinking Water and Toxic Enforcement Act of 1986). ELF takes the position that high acrylamide levels in potato chips are not inevitable:

“Research has demonstrated that acrylamide levels in potato chips can be reduced by a number of processes including, but not limited to: (1) choosing different varieties of potato; (2) avoiding sugar dips/ coatings in partially cooked products; (3) increasing product moisture; (4) lowering pH; (5) storing products at higher temperatures; (6) changing temperature / cooking regimes; (7) cooking products at lower temperatures; (8) adding asparaginase; (9) replacing ammonium; and, (10) changing cooking oils.”

In time, the food industry will likely adapt some of these changes.  Scientists from fifteen countries met in June 2005 at the request of the United Nation’s committee on food additives.  One of the key points made at this conference is that acrylamide can in fact be reduced, as described above, by a variety of techniques. The most effective measure, it appears, is to add the enzyme asparaginase prior to heating as a means to remove the amino acid asparagine.[i]

Unfortunately, acrylamide is not specific to potato chips. Higher levels can be found in any carbohydrate foods that are roasted, baked, or fried at temperatures above 250 degrees Fahrenheit.  Boiling foods (potatoes for instance) does not appear to produce any of the toxin because temperatures do not exceed 250 degrees. Scientists convening at the United Nation committee meeting estimate that a person’s total food exposure to acrylamide, on average, can be estimated as follows: potato chips (16-30 percent), french fries (6-46 percent), coffee (13-39 percent), pastry and sweet biscuits (10-20 percent) and bread and rolls/toasts (10-30 percent).

The Center for Science in the Public Interest (CSPI) is taking a strong position, insisting that the FDA limit acrylamide in common foods.  In 2002, the FDA determined that an intake of 12 micrograms of acrylamide per person per day is a safe amount in terms of the nervous system. CSPI estimates that the average American consumes three times the safe amount each day, or 36 micrograms. It’s easy to exceed the threshold level of 12 micrograms based on the acrylamide content of certain foods:

  • A cup of coffee has 2 micrograms
  • A cup serving of Cheerios has 7 micrograms.
  • A slice of toast has 10 micrograms.
  • A 1 oz. serving of Pringles Potato Crisps has 28 micrograms.
  • A large McDonald's French Fries has 82 micrograms.

Before you get too worried about these numbers, remember that there is still no evidence that these levels cause cancer or other neurological problems in humans. The research conducted on animals found cancer when animals were fed extremely high doses of acrylamide.  To approximate the dose used in animal studies, a 154-pound person would need to consume in excess of 5,000 - and by some accounts as much as 35,000 micrograms of acrylamide every day.

Harvard researchers conducted a case-control study of cancer patients in a five-year study and found no association between the consumption of acrylamide from foods and increased risk of cancers of the bladder, colon, and kidney (published in The British Journal of Cancer in 2003). Critics claim that the study was not sensitive enough nor did it consider the cancers that were found in the animal studies: lung, testes, breast, and uterus. As of this publication, the FDA and other organizations are working to assess the potential adverse effects of acrylamide.

Hippie Wisdom
Roasted carbohydrate-rich vegetables (ex. root vegetables) and fruits (ex. plantains) have been a part of the human diet since fire was first cultivated as a cooking method two million years ago. Breads and other grain-based foods have been baked in fires for thousands of years. Acrylamide is not a new carcinogen to the body, a fact that raises the question, how does a healthy body prevent DNA damage?

The body has many different defense systems, from general antioxidants like vitamin C, vitamin E, and beta-carotene, to enzyme complexes like superoxide dismutase, catalase, and glutathione peroxidase. Selenium, manganese, zinc, and other minerals are essential components of these systems (selenium and glutathione are both found in nutritional yeast). In addition, just how specific phytochemicals such as lignans found in flaxseed and flax oil might prevent cancer, is being studied. 

A diet based predominantly on quality whole foods provides the body with the nutrients needed to reduce the risk of cancer.  Imagine how damaging it might be to eat a diet of potato chips, french fries, pastries, and other baked/fried carbohydrates without also eating many fruits, vegetables, legumes, whole grains, and other nutrient-dense foods? Well, this sad diet is currently eaten by millions of Americans, a fact that makes this newfound food-based carcinogen an even greater public health concern.

That being said, for now it’s best to choose quality snack chips made without hydrogenated oils or preservatives. The natural food store offers several brands that are cooked with high-oleic sunflower or high-oleic safflower oil (both rich in healthier monounsaturated fats). Also, look for organic potato chips (Kettle Foods and Westbrae both sell organic potato chips) since potatoes are one of the (twelve fruits and vegetables that contain the highest pesticide residues). Enjoy quality potato chips that would make George Crum proud.

More information on acrylamide:

- Greg Hottinger, MPH, RD

[i] United Nations Committee Findings: