Pistachios - the healthiest of them all?

Pistachios (Pistacia vera) are a member of the Anacardiaceae family and are related to cashews, mangoes and cherries. Cultivation of pistachios dates back further than 6500 BC. Pistachios are native to parts of Central and West Asia, Middle Eastern countries and are distributed throughout the Mediterranean.

Pistachio trees can live up to 300 years and give way to a green and purple coated nut within a clam-shaped shell. When the pistachio fruit ripens, the shell changes from green to a warm yellow colour and splits open. This is called dehiscence and can be heard with a ‘pop’.

So unshelled pistachios that remain closed are in fact unripe, and in all honesty, are not worth the labour involved to eat them!

Pistachio nutritional profile

• High in unsaturated fats - brain and cell membrane function
• High in linolenic acid - anti inflammatory
• High in fibre - helps with cholesterol and digestive function
• High in magnesium, copper and vitamin B1
• Very high in vitamin B6 - important for progesterone, neurotransmitters and energy
• Powerful antioxidants from polyphenols -  lutein, alpha and beta carotene and tocopherol
• Pistachios contain arginine - precursor to nitric oxide, which relaxes blood vessels

I must say it’s rare to find any intervention, let alone a food, that yields such a robust set of research which covers multiple age groups, populations and areas of health.

The cool thing about assessing foods such as pistachios, is that they are generally regarded as safe with minimal or no side effects. We can also see in real time their beneficial health outcomes.

Pistachios health benefits

• Aids in weight management
• Improves diabetes symptoms
• Supports microbiome diversity
• Cholesterol & vascular health
• Improves sexual function

There are many studies showing pistachios to be very protective for cardiovascular and metabolic health. According to the research, diabetes, heart disease, high cholesterol, systemic inflammation and vascular conditions are all health concerns in which pistachios may be beneficial.

Maternal Health & Gestational Diabetes

In 2019, a study known as the St. Carlos Gestational Diabetes Mellitus Prevention Study was conducted. It included just under 700 pregnant women, half of whom were instructed to eat a Mediterranean diet to assess outcomes on gestational diabetes. These women were also advised to have 30g pistachios per day, which is roughly a handful, along with extra virgin olive oil. These women also walked for around 30 minutes per day. The other half were advised to restrict or avoid dietary fat, including from nuts, seeds and olive oil and stick to a standard diet of their choosing.  Women in the pistachio and olive oil group gained less weight than the control group. There was also a significant reduction in gestational diabetes in the pistachio group. This study also revealed beneficial outcomes to the newborns of these women, including high rates of healthy birth weight, lower incidence of perineal trauma and lower rates of emergency caesareans. These factors may well be resulting from Mediterranean diet more so than pistachios, however it speaks of how important dietary interventions can be for pregnant women and their babies.

Pistachios protect pancreatic cells

49 pre-diabetic participants consumed a pistachio-supplemented diet. DNA oxidative damage to pancreatic cells was reduced and telomere length was retained in the pistachio group. This means pistachios have a protective effect on pancreatic beta cells that produce insulin and may improve their expression, thereby improving diabetic outcomes.

Nutrient profile and weight management

A 2020 study published in the journal Appetite, assessed the impacts of pistachios on women’s body weight, composition, satiety and nutrient intake. This 12 week study saw 60 premenopausal women eating 44 g of pistachios daily or a control diet. The women reported feeling a sense of fullness (satiety) following pistachio consumption. Monounsaturated and polyunsaturated fats were increased in blood samples from the pistachio group. Body composition and weight were unchanged at the end of the study. This means that although pistachios are high in energy, the women eating them did not gain weight or have any changes in body fat distribution. This led the authors to conclude that pistachios are effective in maintaining healthy weight and nutrient profiles and should be included as part of a healthy balanced diet.

Meta-analysis on cholesterol

Taking a birds-eye-view of the data, a recent meta analysis examined 34 clinical trials with 1677 participants in total. The authors compared the health effects of walnuts, pistachios, hazelnuts, almonds and cashews. Specifically, the impact on cholesterol profiles and cardiovascular health was assessed. Pistachio-supplemented diets rated the highest for improving triglycerides and LDL cholesterol, which can be inflammatory in high levels. This is a fairly significant finding, as all nuts are healthy, yet when going head to head, pistachios are a clear winner.

Metabolic syndrome

A 24-week randomized controlled trial included 60 men with metabolic syndrome. In this study, half these men consumed pistachios for just 3 weeks and several cardiometabolic markers were measured. Weight, abdominal adipose tissue, fasting blood glucose, fasting insulin and glycosylated hemoglobin among other parameters all showed vast improvements. The results showed that conditions such as diabetes, fatty liver disease and hypertension could all benefit from pistachio-enriched dietary intervention.

Glucose metabolism

A Spanish study with 54 participants consumed either 57g of pistachios per day as part of a usual diet or a control diet with no pistachios for 4 months. Pistachio-rich diets improve cellular glucose uptake, decrease insulin resistance and lower inflammatory markers such as fibrinogen and oxidized LDL particles. This means pistachios could be useful in treating prediabetes and any related metabolic condition like heart disease.

Diabetes Management

Pistachios are naturally high in fat and complex carbohydrates. This makes them a favourable option for diabetics to manage blood glucose levels. A 2008 study involving 108 participants with type 2 diabetes consumed either a full dose of nuts including pistachios, a half-dose or none over 3 months. Nut intake, with the inclusion of pistachios as a replacement for carbohydrates improved glycaemic control and cholesterol profiles in individuals with type 2 diabetes.

Weight loss

A randomized controlled study with 100 generally healthy yet overweight participants were assigned to either a control or pistachio-supplemented diet over 4 months. At the end of the study, the participants who had eaten 42g of pistachios per day lost weight, had lower BMIs and lower blood pressure compared to the control group.

Microbiome

Pistachios, like all nuts, are a natural source of prebiotic foods, which benefit intestinal bacteria. These substrates in nuts help maintain microbial diversity and promote overall digestive and immune health. The effect of pistachio consumption on microbiome composition was analysed in a randomised trial by Ukhanova et al. (2014). The results showed pistachio consumption had a potent effect on increasing beneficial gut microbe numbers.

Sexual function

17 male patients with diagnosed erectile dysfunction (ED) for more than 12 months were included in a study conducted by Aldemir et al. (2011). After consuming 100g of pistachios per day for 3 weeks, the men with ED in this study reported improvements in erectile function along with improved cholesterol levels. The participants also reported no side effects. The authors noted that arginine in pistachios could be responsible for maintaining arterial blood flow throughout the body and therefore help improve ED symptoms.

Storage and cooking

Unshelled pistachios are likely to have a longer shelf-life, unlike their shelled counterparts. Pistachios are so delicious in my view, that the effort required to crack the half-split shell is worth it for the reward. Pistachios are excellent on their own or are also found in many Middle Eastern savoury and sweet dishes.