Pistachios are an energy-dense food high in protein, fat, and fiber.¹

At about 6 grams of protein per ounce, pistachios are one of the top nut sources of protein. Yet they have a lower fat content compared to other nuts (about 13 grams per ounce). These factors make pistachios one of the lowest-calorie nuts available, at just 159 calories per ounce.²

As a result, pistachios are a valuable snack for anyone trying to maintain a healthy weight or blood sugar levels. Indeed, one review of 11 studies found that, compared to people on control diets, those who regularly ate pistachios tended to have a lower body mass index (BMI).³

Another review of six studies showed that consuming pistachios significantly reduced fasting blood glucose levels and improved insulin resistance in people with type II diabetes, prediabetes, and metabolic syndrome.⁴ Pistachios provide protective effects for eye health as well.⁵

These green nuts contain lutein, a plant pigment that is an important component of the macular pigment, the yellow substance in the retina that protects eyes from UV damage.

A study of older adults with habitually low lutein and zeaxanthin intake and low macular pigment optical density (MPOD), showed that consuming 2 ounces of pistachios per day for 12 weeks resulted in:

• a significant increase in macular pigment optical density (MPOD), and
• increases in serum concentrations of lutein.⁵

MPOD is a measurement of the concentration of macular pigment in the retina. Higher MPOD helps protect the eye from UV damage, while low levels have been associated with increased risk of age-related macular degeneration.⁶

The researchers concluded, "Pistachio consumption could be an effective dietary strategy for preserving eye health."⁵ 

The easiest way to enjoy pistachios is cracking open their shells and eating them as a tasty snack. In fact, one study showed that people who ate in-shell pistachios consumed 41% fewer calories, compared to those who ate the pre-shelled nuts.⁷

One ounce of pistachios is about 49 nuts.²

References

1. Dreher ML. Pistachio nuts: composition and potential health benefits. Nutr Rev. 2012 Apr;70(4):234-40.
2. Available at: https://fdc.nal.usda.gov/food-details/170184/nutrients. Accessed April 15, 2025.
3. Xia K, Yang T, An LY, et al. The relationship between pistachio (Pistacia vera L) intake and adiposity: A systematic review and meta-analysis of randomized controlled trials. Medicine (Baltimore). 2020 Aug 21;99(34):e21136.
4. Nowrouzi-Sohrabi P, Hassanipour S, Sisakht M, et al. The effectiveness of pistachio on glycemic control and insulin sensitivity in patients with type 2 diabetes, prediabetes and metabolic syndrome: A systematic review and meta-analysis. Diabetes Metab Syndr. 2020 Sep-Oct;14(5):1589-95.
5. Scott TM, Ogunbodede O, McKay DL, et al. Pistachio Consumption Increases Macular Pigment Optical Density in Healthy Adults: A Randomized Controlled Trial. J Nutr. 2025 Jan;155(1):168-74.
6. Masri A, Armanazi M, Inouye K, et al. Macular Pigment Optical Density as a Measurable Modifiable Clinical Biomarker. Nutrients. 2024 Sep 27;16(19).
7. Honselman CS, Painter JE, Kennedy-Hagan KJ, et al. In-shell pistachio nuts reduce caloric intake compared to shelled nuts. Appetite. 2011 Oct;57(2):414-7.