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Pistachios May Boost Vascular Health in Diabetics

Pistachio Nuts

Story at-a-glance -

  • Eating two servings of pistachios a day lowered vascular constriction during stress, which means the load on your heart is reduced since it is easier to pump blood when your arteries are more dilated
  • Diets containing pistachios reduce systolic blood pressure and vascular responses to stress in adults with high cholesterol
  • Pistachios are high in lutein, beta-carotene, and vitamin E compared to other nuts. Eating one or two servings of pistachios a day has been shown to increase blood levels of antioxidants
  • People who ate pistachios, in particular, for 24 weeks lost an average of 0.7 inches from their waists, reduced cholesterol by 15 points, improved their blood sugar, and lowered inflammation
  • Pistachios are at high risk of contamination by aflatoxin and may be bleached or fumigated during processing; choose organic pistachios and avoid those that are dyed, bleached, or show signs of decay

By Dr. Mercola

Pistachios have been enjoyed in the Middle East, where they originated, for thousands of years. Once considered a delicacy, they became a popular snack in the US during the 1880s, when imported pistachios were available from vending machines in bars, restaurants, and train stations. At that time, you could get “a dozen pistachios for a nickel.”1

Pistachios didn’t become widely cultivated in the US until relatively recently; the first commercial crop in the US was harvested in 1976. Today, pistachios are grown in California, Arizona, and New Mexico, bringing in sales of more than $1.1 billion a year.2

Many people feel guilty indulging in nuts, believing them to be too high in fat. But pistachios, like most nuts, are high in fats that are beneficial to your health, and contain many other health-boosting properties as well.

Nutritionally, over half the fat in pistachios is from oleic acid, the same fat that is in olive oil. One cup would have 56 grams of fat, 26 grams of protein, and only 13 grams of carbs. Contrast this to macadamia nuts where one cup has nearly twice the fat and half the protein and 19 grams of carbs.

Pistachios Support Heart Health, Especially in People with Diabetes

Nuts are well established in the medical literature to help reduce your risk of heart disease, and this is especially important in people with type 2 diabetes, who have a heightened risk of heart problems.

A recent study found eating two servings of pistachios a day lowered vascular constriction during stress, which means the load on your heart is reduced since your arteries are more dilated.3

Those eating pistachios also had significantly lower blood pressure, specifically systolic blood pressure during sleep. This was reduced by about four points, which researchers said would be “expected to lower workload on the heart.”4

Past research has also shown that diets containing pistachios reduce systolic blood pressure and vascular responses to stress in adults with high cholesterol.5 If you’re interested in protecting your heart health, snacking on nuts is a far better option than snacking on whole grains, which are often touted as a heart-healthy choice.

A study in the journal Circulation found people with abnormally high levels of lipids, such as cholesterol, in their blood were able to significantly reduce their risk factors for coronary heart disease by snacking on nuts while those who snacked on whole-wheat muffins got no such benefit.6

One reason why nuts are so beneficial is that many, including pistachios, contain the amino acid l-arginine, and is a precursor of nitric oxide, which offers multiple vascular benefits to people with heart disease, or those who have increased risk for heart disease due to multiple cardiac risk factors. 

Pistachios Are Rich in Antioxidants

Pistachios are high in lutein, beta-carotene, and gamma-tocopherol (vitamin E) compared to other nuts. Eating one or two servings of pistachios a day has been shown, in fact, to increase blood levels of antioxidants and, in turn, lower oxidized LDL cholesterol in people with elevated levels.7

While most people think of fruits and vegetables when it comes to increasing antioxidant intake, the research suggests that eating pistachios is another simple strategy to consume more of these beneficial phytochemicals. A study in Nutrition Reviews reported:8

“The pistachio is a nutrient-dense nut with a heart-healthy fatty-acid profile as well as protein, dietary fiber, potassium, magnesium, vitamin K, γ-tocopherol, and a number of phytochemicals. The pistachio's unique green and purple kernel color is a result of its lutein and anthocyanin content.

Among nuts, pistachios contain the highest levels of potassium, gamma tocopherol, vitamin K, phytosterols, and xanthophyll carotenoids. Five published randomized cardiovascular trials have shown that pistachios promote heart-healthy blood lipid profiles.

Exploratory clinical studies suggest that pistachios help maintain healthy antioxidant and anti-inflammatory activity, glycemic control, and endothelial function.”

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Pistachios Target Belly Fat, Help You Maintain a Healthy Weight

If weight loss is on your agenda, snacking on nuts makes sense. Rich in satiety-inducing protein, fat, and fiber, research shows that eating nuts two or more times per week is associated with a reduced risk of weight gain.9

People who ate pistachios, in particular, for 24 weeks lost an average of 0.7 inches from their waists, reduced cholesterol by 15 points, improved their blood sugar, and lowered inflammation.10 When people eat nuts, it seems, they often use them to replace processed foods, which is one reason why they’re associated with weight loss.

Further, they’re an excellent source of monounsaturated fatty acids, which tend to “preferentially target belly fat,” according to the study’s lead researcher.11 And according to Nutrition Reviews:12

“When consumed in moderation, pistachios may help control body weight because of their satiety and satiation effects and their reduced net metabolizable energy content.

One study with subjects in a weight-loss program demonstrated lower body mass index and triglyceride levels in individuals who consumed pistachios compared with those who consumed an isocaloric pretzel snack.”

Yet another study, this one published in the Journal of the American College of Nutrition, also found that those who ate nuts gained numerous benefits compared to non-nut eaters, including:13

  • Decreased body mass index and waist circumference
  • Lower systolic blood pressure
  • Lower weight
  • Less likelihood of having two risk factors for metabolic syndrome: high blood pressure and low HDL (good) cholesterol (for nut consumers)
  • Less likelihood of having four risk factors for metabolic syndrome: abdominal obesity, high blood pressure, high fasting glucose, and a lower prevalence of metabolic syndrome (for tree nut consumers)

There’s even something known as the “pistachio principle,” which suggests eating in-shell pistachios can help you to eat fewer calories without even trying to restrict them. Dr. James Painter of Eastern Illinois University, found that people who consume in-shell pistachios consume 41 percent fewer calories than those who consume them without shells.

A second study found that leaving empty pistachio shells on your desk after consumption reduces calorie intake by 18 percent compared to discarding the shells immediately.14 The shells, it seems, help to serve as a visual reminder of how much you’ve eaten, helping you become more mindful of your food intake.

Avoid White or Bleached Pistachios

Pistachios are an extremely perishable, fragile crop. Once harvested, they must be processed within 24 hours or else tannins released from the nut’s hull can lead to staining on the shell. Stained pistachios can no longer be sold in shell, and must be removed and sold as nutmeats (generally for a lower profit).

You may have seen red or green dyed pistachios on the market, and this is often done to hide such staining. Naturally, pistachio shells are light beige in color, but in some areas, especially China, an even lighter, virtually white shell is thought to indicate cleanliness and freshness. To get this white shell, 90 percent of the pistachios sold in the Chinese market have been bleached, even though it is against China’s Food Safety Laws.15

Aside from the potential for bleach residues to remain on the nuts, bleaching has been shown to destroy important phytochemicals in pistachio skins, with researchers noting that the “destruction of bioactive phenolics in pistachio skins [from bleaching] may negatively impact the potential health benefits arising from pistachio consumption.”16

California pistachio shells are not bleached, however, once hulled they may be soaked in a “bath” of water and antimicrobial chemicals. The most commonly used antimicrobial is hypochlorous acid (bleach).17 The nuts are then moved to conveyer belts to be dried, but are first washed with a water spray to remove any additional organic matter.

At this point, they may be sprayed again with an antimicrobial, although the California Pistachio Research Boards says that this is “not currently practiced.”18 The Codex Recommended International Code of Hygienic Practice for Tree Nuts also notes that fumigation with methyl bromide or phosphine can be used to control insects in stored nuts, stating that “it may be necessary to repeat fumigation periodically depending on the conditions and duration of storage.”19 To avoid nuts that have been treated with antimicrobials and pesticides, choose organic pistachios.

Pistachios Are a High Risk for Aflatoxin

Pistachios, like peanuts, are at high risk of being contaminated with a carcinogenic mold called aflatoxin. Aflatoxin is said to be the most carcinogenic naturally occurring substance known, and it is known to cause liver cancer and immune suppression in humans. Levels of aflatoxin in US-grown pistachios are generally low. However, pistachios from Iran and Morocco have been found to contain dangerously high levels.20

To minimize this risk, be sure the pistachios you eat come from a reliable supplier, which dries the nuts immediately after harvest to minimize decay. Some California pistachio farmers are also using spores of a beneficial fungus to displace the fungi that produce aflatoxin. This strategy has been found to reduce aflatoxin by up to 45 percent, without the use of chemicals.21 You can further reduce your risk by:

  • Choosing in-shell pistachios (shelled pistachios are much more likely to be contaminated with aflatoxin)
  • Avoiding dyed pistachios, which may cover up staining
  • Avoiding eating pistachios that have a sour taste or signs of mold, excessive moisture, or insect damage

Roasting Pistachios May Damage Nutrients

To increase the positive impacts on your health, look for nuts that are organic and raw, not roasted. Roasting has been found to damage nutrients in nuts, including decreasing the availability of beneficial fatty acids and amino acids.22 A better option would be nuts that are hot-air dried at temperatures of 180 degrees (F) or less, which should help to minimize any potential heat-related damage. An even better option is to consume pistachios raw, and soak them first for eight to 12 hours. Phytic acid, which is found in the coatings of nuts, is an "anti-nutrient" responsible for leaching vital nutrients from your body. Soaking nuts will help to get rid of the phytic acid and enzyme inhibitors, which can interfere with the function of your own digestive and metabolic enzymes, in the nuts.  

To make them more palatable you can use a dehydrator to improve the texture. Enzyme inhibitors in nuts (and seeds) help protect the nut as it grows, helping to decrease enzyme activity and prevent premature sprouting. When nuts are soaked, the germination process begins, allowing the enzyme inhibitors to be deactivated and increasing the nutrition of the nut significantly, as well as making them much easier to digest. One exception is with macadamia nuts (and other white nuts), which have only negligible amounts of enzyme inhibitors, so soaking is not as necessary.

What Are the Healthiest Nuts?

Pistachios, provided they are organic, not bleached and not contaminated with aflatoxin or fumigants, provide a beneficial source of antioxidants and other nutrients. My favorite nuts, however, are macadamia and pecans, as they provide the highest amount of healthy fat while being on the lower end in terms of carbs and protein. Most nuts' nutritional makeup closely resemble what I consider to be an ideal ratio of the basic building blocks—fat making up the greatest amount of your daily calories, followed by a moderate amount of high-quality protein, and a low amount of non-vegetable carbs.

The main fatty acid in macadamia nuts is the monounsaturated fat oleic acid (about 60 percent). This is about the level found in olives, which are well known for their health benefits. Generally speaking, each type of nut will offer a slightly different mix of nutrients for your health, so it's a good idea to include a variety of nuts rather than sticking to one at the exclusion of all others. In addition to pistachios, you may want to consider adding the following beneficial nuts to your diet as well:

  • Raw macadamia nuts are a powerhouse of a nut, containing a wide variety of critical nutrients including high amounts of vitamin B1, magnesium, manganese, and healthful monounsaturated fat, just to name a few. They have the highest fat and lowest protein and carb content of any nut. This is particularly helpful if you are seeking to implement intermittent fasting and treating insulin resistance.
  • Pecans: Pecans contain more than 19 vitamins and minerals, and research has shown they may help lower LDL cholesterol and promote healthy arteries. One of my favorite treats is candied pecans in a salad at a restaurant. I know they have sugar, but a few grams or less a day is not going to cause a major problem provided you're eating a healthy whole food diet as opposed to processed foods (which are loaded with hidden fructose). Pecans are a close second to macadamia nuts on the fat and protein scale.
  • Walnuts: Walnuts are good sources of plant-based omega-3 fats, natural phytosterols, and antioxidants that are so powerful at free radical scavenging that researchers have called them "remarkable."23 Plus, walnuts may help reduce not only the risk of prostate cancer, but breast cancer as well. They've also been shown to reverse brain aging in rats and boost heart health in people with diabetes.
  • Almonds: One of the healthiest aspects of almonds appears to be their skins, as they are rich in antioxidants including phenols, flavonoids, and phenolic acids, which are typically associated with vegetables and fruits. A study in the Journal of Agricultural and Food Chemistry even revealed that a one-ounce serving of almonds has a similar amount of total polyphenols as a cup of steamed broccoli or green tea.24
  • Brazil Nuts: Brazil nuts are an excellent source of organic selenium, a powerful antioxidant-boosting mineral that may be beneficial for the prevention of cancer.