Extracting the Goods

Screen Shot 2016-12-16 at 11.23.18 AM

Fearsome Yellow

yellowNext time you think of welcoming someone home by tying a yellow ribbon around an old oak tree, you might want to think again. According to a widely circulating report the yellow dye could leave a toxic residue on your hands. What are we talking about? PCBs. Actually one specific PCB, namely PCB-11. Polychlorinated biphenyls have become an environmental pariah, accused of being endocrine disruptors and carcinogens. Quite a comedown for chemicals that were once revered as ideal heat transfer fluids and insulating materials in electrical equipment. They were phased out in the 70s when researchers discovered that these compounds persisted in the environment and were toxic to animals. Aside from PCBs’ ability to cause a type of acne known as chloracne, no significant adverse effects have been noted in humans. In two classic cases, one in Japan and one in Taiwan, a number of people became ill after consuming rice bran oil that had become contaminated with PCBs, but it turned out that the problem was toxins that had formed when the PCBs were heated to a high temperature. Polychlorinated biphenyls are no longer produced but some can form as a byproduct of certain chemical reactions. This is where the yellow dye comes into the picture.

In many cases, although certainly not always, yellow pigments are made by mixing blue pigments with green ones. A classic blue pigment is “phthalocyanin blue” which was discovered accidentally by a chemist working at a plant that was producing phthalimide, a chemical used to make certain plastics. He was troubled by blue contamination of the product that was eventually traced to a by-product formed when the phthalimide reacted with trace amounts of iron leaching out from the metal reactor. Research then showed that substituting copper for iron resulted in a more stable pigment. And if this blue pigment, also known as Monastral blue, were reacted with chlorine, it was converted to a green color, appropriately named “phthalocyanin green.”

This is where the issue of PCBs arises. When the blue pigment is reacted with chlorine, PCB-11 forms as a contaminant and is carried through to the yellow dye that is made by mixing the blue and green phthalocyanins. This dye is used in many fabrics, paper products and paints that we come into contact with. Hence the warnings. Has anyone ever shown that people exposed to yellow clothing have higher levels of PCBs in their blood? No. And given the trace amounts of PCBs present in the yellow dye, nobody is ever likely to show anything like that. But just mentioning PCBs and yellow clothing in the same sentence is enough to make some people shed these garments. Coincidentally, yellow is the color of fear. In this case, irrational fear. Headlines such as “Your favourite yellow sweatshirt could be making you sick” amount to needless fear mongering. Makes me sick.

Joe Schwarcz

Pistachios reputed to have some uplifting health benefits

pistachiosRemember when it wasn’t hard to determine if someone had been into the pistachio bowl? They’d be caught red-handed! That’s because until artificially coloured foods became a pariah, pistachio nuts, which are actually not nuts but the seeds of a fruit, often used to be coloured red. Exactly why that was the case is a matter of some controversy.

Some suggest that when pistachios were first imported into North America back in the 1930s, mostly from Iran, the shells tended to be blemished as a result of hand-picking. Since Americans didn’t care for blemished food, the pistachios were dyed red.

Others suggest that the red colour was added to distinguish the newly introduced nuts from other varieties to attract attention. Another possibility is that in Iran, traditionally, the nuts were soaked in brine and then roasted in the sun which resulted in a pinkish coloured shell — and importers added red dye to achieve a uniform product.

The fact is that nobody really knows how the tradition started, or indeed what dye was used, although some accounts make reference to a “vegetable dye,” probably beet juice. With concerns being raised about food additives, red pistachios have mostly disappeared, although a few companies still produce them for consumers mired in nostalgia. The vast majority of pistachios sold in North America now come from California, and instead of attracting consumers with colour, producers hope to attract them with science. The hook is a possible benefit in the prevention of heart disease — and believe it or not, help with erectile dysfunction.

Nuts are low in saturated fats, high in monounsaturates and are rich in antioxidants, so it comes as no great surprise that epidemiological studies have demonstrated a link between increased nut consumption and reduced risk of cardiovascular disease. Pistachios have a chemical profile similar to nuts and have therefore been studied in terms of reducing cardiovascular risk. In one small study, subjects were asked to consume either 40 grams, 80 grams or no pistachios daily. The pistachio consumers lowered their LDL cholesterol (the “bad guy”), but interestingly, there was no difference between the 40 or 80 gram consumers. So one pistachio snack seems to be enough; more is not better.

But does this extra consumption not lead to weight gain? Apparently not. A study in China examined the pistachio effect in some 90 subjects diagnosed with metabolic syndrome, which is a combination of disorders that increase the risk of developing cardiovascular disease and diabetes. Although there are some variations in the definition of metabolic syndrome, it basically means a high waist circumference combined with any two of elevated triglycerides, reduced HDL cholesterol (the “good guy”), raised blood pressure, raised fasting glucose, or previously diagnosed Type 2 diabetes. In the Chinese study, subjects consumed either no pistachios, or 42 grams or 70 grams for 12 weeks. There were no changes in body-mass index or waist-to-hip ratio. Curiously, there was also a slight improvement in triglyceride levels in the 42-gram group but not the others.

Pistachios have also been the subject of a study by Dr. James Painter of Eastern Illinois University who coined the term “pistachio principle,” referring to an effect by which the body is fooled into eating less by using visual cues.

Painter found that when subjects were offered either shelled or in-shell pistachios, there was a significant difference in calorie intake but no difference in degree of satisfaction. Subjects offered shelled pistachios consumed 41 per cent fewer calories, the assumption being that the reduction in calories was due to the additional time needed to shell the nuts or perhaps to concern about the extra volume perceived when the nuts were in their shell.

In a subsequent study, subjects were allowed to consume in-shell pistachios at their leisure with the shells being discarded in a separate container. For half the subjects the container was periodically emptied. In the case where the containers were emptied, subjects consumed fewer nuts without any difference in fullness or satisfaction ratings. The conclusion was that leaving pistachio shells as a visual cue to consumption may help consumers consume fewer calories.

The point of the “pistachio principle” is not to encourage eating fewer nuts. Rather, the point is that altering environmental cues can lead to satisfaction with less food. For example, studies show that large-package size increases caloric consumption by some 22 per cent. Buying single-serve potato chips and small-size candy bars as opposed to “family bags” reduces consumption. Of course, it is far better to forget the chips and candy bars and eat pistachios instead.

Now we come to the most intriguing effect of pistachio consumption, an improvement in erectile dysfunction.

Pistachios are rich in arginine, an amino acid that leads to nitric-oxide production, a chemical known to improve blood flow to the penis. A paper published in the International Journal of Impotence Research contends that pistachios may raise more than just hopes for men suffering from ED. Subjects who consumed 100 grams of pistachios a day for three weeks showed an improvement based not only on subjects’ reports, but on measurements of penile blood flow as well. Perhaps this is why historically pistachios have been considered to be the food of royalty.

According to legend, the Queen of Sheba pronounced that pistachios were to be an exclusive food offered only to the royal household. When the Queen heard of the great wisdom of King Solomon, she journeyed to see him with gifts of spices, precious stones and gold. As the Bible tells us, King Solomon reciprocated and “gave to the queen of Sheba all her desire, whatsoever she asked.” Not sure what she asked for, but at least according to the 1959 epic film Solomon and Sheba starring Yul Brynner and Gina Lollobrigida, the couple’s meeting blossomed into romance. Perhaps pistachios had been part of the Queen’s gifts.

A passion for pistachios was also exemplified by Nebuchadnezzar, the ancient king of Babylon. It is said that in his hanging gardens he had planted pistachio trees. Akbar the Great, a Mogul Emperor, would hold royal feasts that were fit for a king. He usually served chickens that had been fed pistachio nuts for at least six to eight weeks to enhance their flavour. And maybe enhance something else as well. Some marketer is probably thinking right now of colouring pistachios a Viagric blue.

 

Joe Schwarcz

Blog authors are solely responsible for the content of the blogs listed in the directory. Neither the content of these blogs, nor the links to other web sites, are screened, approved, reviewed or endorsed by McGill University. The text and other material on these blogs are the opinion of the specific author and are not statements of advice, opinion, or information of McGill.