If nuts aren’t a staple in your daily diet, they ought to be. That’s especially true if you’re at increased risk for type 2 diabetes.
According to researchers from Pennsylvania State University, eating an average of 52 g of nuts a day can reduce the likelihood of developing insulin resistance, a precursor to type 2 diabetes. It’s estimated that up to 50 per cent of people with insulin resistance will develop diabetes if they don’t make lifestyle changes.
Previous studies have suggested that eating nuts regularly is tied to better blood glucose (sugar) control and protection from type 2 diabetes. Most studies, however, were observational, not randomized controlled trials, and therefore don’t prove cause and effect.
About the study
The research, published in the American Journal of Clinical Nutrition (2019), was a review of data pooled from 40 randomized controlled trials that examined nut consumption on blood glucose control in 2,832 people with and without diabetes.
The studies looked at all types of nuts: tree nuts (e.g., almonds, brazil nuts, cashews, hazelnuts, macadamia nuts, pecans, pine nuts, pistachios, walnuts) and peanuts, which botanically speaking are legumes, not tree nuts.
Blood tests that were reviewed included fasting blood sugar, hemoglobin A1C (one’s average blood sugar level over the past three months) and fasting insulin. The researchers also looked at insulin resistance.
Insulin resistance occurs when your cells become less sensitive to the blood-sugar-clearing effects of the hormone insulin. This signals your pancreas to produce more of the hormone, driving up insulin levels.
Overall, there was no effect of eating tree nuts or peanuts on fasting blood sugar or hemoglobin A1C. However, when the researchers looked at specific types of nuts, they found that eating pistachios was associated with a significant reduction in fasting glucose.
Eating nuts was also tied to significantly reduced fasting insulin and insulin resistance, especially in people with prediabetes. No one particular type of nut accounted for this effect.
Pre-diabetes occurs when fasting blood sugar is higher than normal (6.1 – 6.9 mmol/L), but not yet high enough to be considered diabetes (7.0 mmol/L or higher). Some of the long-term complications of diabetes, such as heart disease and nerve damage, may begin during prediabetes.
Nuts are high in healthy unsaturated fats, fats thought to help improve insulin sensitivity. Dietary fibre and magnesium in nuts may also play a role.
Pistachios and walnuts are a good source of alpha linolenic acid (ALA), an omega-3 fatty acid linked to protection from type 2 diabetes.
Scientists also speculate that the unique combination of unsaturated fats and antioxidants in pistachios may be responsible for their effects on insulin sensitivity.
What about weight gain?
Nuts are high in calories, due mainly to the fats they contain. The concern: eating nuts every day can lead to weight gain therefore undoing their health benefits.
The current analysis of 40 studies, though, revealed that the beneficial blood glucose effects of eating nuts did not differ whether participants lost or gained weight during the study duration.
Even so, 52 g of nuts, the average daily intake across the 40 studies, is equivalent to 300 calories worth of almonds (43 nuts), 340 calories of walnuts (26 halves) or 290 calories of pistachios (74 kernels).
To prevent adding excess calories to your diet, swap nuts for snacks like granola bars, crackers, cookies and chips. Substitute nuts for granola as a topping on yogurt.
Replace meat in stir-fries with nuts, which, in addition to unsaturated fat and fibre, add plant-based protein.
Measure and pre-portion nuts for snacks. Eating nuts in the shell, like pistachios, can also help control portion size since it takes more time to crack and eat them.
All research on this web site is the property of Leslie Beck Nutrition Consulting Inc. and is protected by copyright. Keep in mind that research on these matters continues daily and is subject to change. The information presented is not intended as a substitute for medical treatment. It is intended to provide ongoing support of your healthy lifestyle practices.