Research & Education

Let's Not Forget About Pistachios

When it comes to grain-free and low-carbohydrate diets almonds get all the love. There’s almond milk for those who are sensitive to dairy almond flour cookies and muffins for the gluten-intolerant and of course almonds eaten as a snack. People who follow strict Paleo diets may avoid peanuts and cashews since these are technically legumes but other nuts are popular such as walnuts for their omega-3 content and Brazil nuts for their high selenium. Beyond these omnivores and vegetarians can agree on enjoying hazelnuts pecans and macadamias for their healthy fats and fiber. But what about pistachios? Seems like they don’t have the spotlight shining on them very often do they?

Like other nuts pistachios stack up pretty well in terms of nutrient content. They offer appreciable amounts of manganese copper phosphorus and vitamins B1 and B6. They also provide small amounts of gamma-tocopherol vitamin K and xanthophyll carotenoids. Lutein and anthocyanins in pistachios are responsible for the eye-catching green and purple color of these nuts. (The red ones don’t occur in nature; they’re dyed in order to mask blemishes that occur during harvesting.) The fat in pistachios is predominantly monounsaturated (about 52%) and while the omega-6 to omega-3 ratio is a whopping 51-to-1 considering the total amount of polyunsaturated fats in an ounce of pistachios is just 3.8 grams the total omega-6—about 3.7 grams—is still very low.

Unfortunately as is the case for all nuts pistachios’ nutritional punch comes wrapped up in a hefty dose of calories. It’s only too easy to sit at the computer or in front of the TV with a bag of shelled pistachios and before you know it half the bag—or more!—has disappeared. “Hand-to-mouth” syndrome is a hazard that accompanies nut consumption in general. Sometimes the only protection against this is that it’s cost-prohibitive. Pistachios aren’t among the most budget-friendly things at the supermarket. However even when price is no obstacle there’s a simple way to enforce portion control without really trying: purchase nuts in the shell. People tend to consume fewer nuts when they have to go to the effort of removing the shell for each one. Not a huge effort granted but the extra little bit of work is enough to deter consuming nuts on autopilot. This isn’t just common sense; it’s actually been studied! 

In a study where college students were provided with a 16-ounce cup of pistachios and instructed to eat them at their leisure during a lecture subjects given in-shell nuts consumed an average of 125 calories compared to an average of 211 calories consumed by subjects given shelled nuts for a difference of 86 fewer calories with the in-shell nuts. A gap of 86 calories isn’t enormous but over time particularly among individuals whose go-to snacks include nuts having to shell each nut before eating it could add up to a substantial caloric reduction. The researchers did not determine whether the lower amount consumed was due to the additional time required to shell the nuts or perhaps to the visual cue of the accumulating pile of shells which may have helped subjects remain aware of how much they were eating. Whatever the underlying reason buying nuts in the shell might be a way to encourage portion control.

Nut consumption in general fits into many healthy dietary patterns. Nuts and seeds are popular in the Mediterranean and Paleo diets and pistachios are no exception. Fortunately one need not have Mediterranean heritage to reap the benefits. A study in Asian Indians with metabolic syndrome showed that adding pistachio consumption to a regimen of increased exercise and a healthy diet resulted in greater improvements to cardio-metabolic risk markers than the same regimen without the pistachios. Consumption of pistachios has been shown to have favorable effects on blood glucose and hemoglobin A1c as well as beneficial effects on fructosamine triglycerides and total-to-HDL cholesterol ratios in type-2 diabetics. Not surprisingly it may be especially helpful to substitute nuts for calories and fats from other foods rather than simply adding them to the habitual diet. Substituting pistachios for a small amount of white bread led to improvements in postprandial glycemia and increased levels of glucagon-like-peptide an incretin signaling molecule that delays gastric emptying and influences satiety.

Where do pistachios fall with regard to rising rates of tree nut allergies? Pistachio allergies seem to be more common in pistachio growing areas so the total amount of exposure may be a factor. Pistachio allergy has significant overlap with allergy to cashews. Another concern regarding nut consumption is presence of the aflatoxin fungus. Peanuts are the food most widely known to potentially be contaminated with aflatoxin but pistachios may present it as well. (Most samples have been found to be below the maximum tolerated level.)

One thing is for sure: those Sicilians know what they’re doing! But if pistachio gelato isn’t your thing maybe pistachio crusted salmon is a good way to go.