Black and brown veggies–are they safe to eat?
Last week two contradictory articles appeared on my computer screen. One told me that brown foods could cause cancer. The other stated that black, charred foods are now “in” and that we should take advantage of these culinary delights. Once again we are torn between what is healthy and what is stylish. Whom should we believe? If brown food is unsafe, then what does that say about black food?
There are two ways that foods become brown. Enzymes can turn foods brown such as when a cut apple is left out in the open. Browning can also happen in the absence of enzymes, particularly during heating. Starches are complex chemicals in foods that can contain free sugars. If these free sugars in the starch react chemically with free amines in proteins, a brown color forms. This series of reactions is called Maillard browning,1 and it is responsible for the golden to brown colors of beer, bread crusts, coffee, chocolate, French fries, potato chips, prunes and toast. Maillard browning not only changes color of food, it also leads to some of the desirable flavors we associate with these products. The problem with food made brown by Maillard reactions is that a natural chemical, acrylamide, can be formed. Acrylamide is considered to be a possible cancer-causing molecule.
Another article encouraged us to look for golden rather than brown. That is a heartening concept. A little acrylamide may not be that much of a problem, but we should try not to overdo it. In other words, some chemicals can be harmful but only in amounts larger than we normally consume them. Toxicologists have been talking about the dose of a toxin being the problem, but critics of chemicals in our food tend to advocate zero tolerance for any toxic molecule. The question then becomes “at what level between golden and dark brown does it become a problem?” It’s hard to say and it also depends on how many of these items we enjoy on a daily basis. I’m not too concerned about the chips and fries as I only treat myself to each of them once or twice a month. The problem becomes more serious when I think about my daily cup of coffee and the prunes I consume to help keep me regular. That is where I suspect that I get most of my acrylamide.
On the other hand, burnt and charred is now fashionable. During charring of vegetables, Maillard browning occurs leading to acrylamide formation. Caramelization, which is not the same as Maillard browning, can also occur. Once a food becomes black, however, a whole new set of problems emerges. Blackened and grilled meats that have been charred are likely to contain polycyclic aromatic hydrocarbons such as benzopyrene. The blacker the food, the more polycyclic aromatic hydrocarbons we are likely to consume. These molecules are carcinogens which are present in the smoke from the grill and also in cigarette smoke. A report last year that cautioned us against eating bacon and other processed meats, also suggested that we should avoid grilled meats.2 In other words, brown may be bad, but black is probably much worse.
What does all of this mean?
First, we need to think before we eat by engaging in mindful not mindless eating.3 Eating brown foods in moderation is probably a safe strategy. I like my bread lightly toasted when heated, but I am cutting back on bread—primarily because I eat too much bread when I have the opportunity and don’t need the extra calories. I don’t worry about acrylamide. I am more concerned about benzopyrene and its relatives. I never have cared for burnt or charred food as the black stuff interferes with enjoyment of the subtle flavors of roasted foods. When I was younger, I cooked my steaks on the Hibatchi once or twice a month. When I bought a Weber grill, I used it to prepare meats two or three times a week. Lately, I have cut way back on grilling.
How can we deal with such contradictory information?
Note that the caution made by a scientific board in Europe was to limit and not eliminate exposure to acrylamide. I was a little disappointed that the emphasis on brown foods was toast and fries with little mention of coffee. The article on burnt foods mentions acrylamide but ignores the greater dangers with polycyclic aromatic hydrocarbons. I would like to see more balance and less sensationalism in what I read on the internet. The key for the mindful eater is moderation and a balanced diet not extremism and a highly restrictive one.
Next week: Book review of Real Food/Fake Food
1Friedman, M. 2015, Acrylamide: inhibition of formation in processed food and mitigation of toxicity in cells, animals and humans. Food & Function 6:1752-1772.
2Bouvard, V., D. Loomis, K.Z. Guyton, Y. Grosse, F. El-Ghissasi, L. Benbrahim-Tallas, N. Guha, H. Mattock and K. Straif, 2015, Carcinogenicity of red and processed meat, The Lancet Oncology 16:1599-1600.
3Wansink, B. 2007, Mindless Eating: Why We Eat More Than We Think, New York: Bantam.