Eating Leafy Greens Linked to Improved Blood Sugar Levels

Eating leafy green vegetables can help balance glucose levels and improve insulin sensitivity, a new study has found.

Consuming more leafy green and cruciferous vegetables — such as broccoli, Brussels sprouts, cabbage, cauliflower, and kale — can improve blood sugar levels and insulin sensitivity, while eating higher amounts of potato chips and french fries can have the opposite effect, according to a new study.

The study, published in the Journal of Clinical Endocrinology & Metabolism, aimed to investigate the association between vegetable and potato consumption with type 2 diabetes (T2D) — a chronic condition caused by insulin resistance in which blood sugar levels are persistently high.

In 2021, the global burden of the disease increased to about 507 million, according to the study.

“T2D is strongly associated with several modifiable risk factors including poor diet, which, alone, accounted for 14.1 million new cases in 2018,” the authors wrote. “While intakes of ultraprocessed foods, red and processed meat, and refined grains are linked to a higher risk of T2D, healthy plant-based foods are recommended to mitigate the risk of T2D.”

As a result, the researchers set out to highlight the importance of green leafy and cruciferous vegetables in lowering the risk of T2D while also determining the impact of potato consumption.

Researchers conducted the study using data from the Australian Diabetes, Obesity and Lifestyle Study, assessing the intake of vegetables and potatoes of 8,009 participants. The participants, aged 25 and older, completed a food frequency questionnaire before undergoing a baseline evaluation one year later, in 1999-2001, and followed by follow-ups in 2004-2005 and 2011-2012.

The participants were evaluated based on their fasting plasma glucose, 2-hour postprandial plasma glucose, serum insulin levels, and insulin sensitivity and β-cell function using the updated homeostasis model assessment (HOMA2-%β for β-cell function and HOMA2-%S for insulin sensitivity). At the end of the 12-year study period, researchers also evaluated the incidence of type 2 diabetes.

Ultimately, they found that higher consumption of vegetables overall was associated with lower post-load glucose levels, while higher intake of green leafy vegetables was associated with improved insulin sensitivity and serum insulin levels.

And while consumption of potatoes cooked in a healthy way did not negatively impact these levels, eating higher amounts of french fries and chips did.

“Our study findings suggest that a diet rich in vegetables, in particular, green leafy, cruciferous, and yellow/orange/red vegetables may help improve glucose tolerance in Australian adults. Moreover, a diet rich in green leafy vegetables might improve insulin sensitivity,” the authors concluded. “Conversely, a higher intake of potato fries/chips, but not potatoes prepared in a healthy way, may worsen glucose tolerance and insulin sensitivity. These findings indicate a nuanced relationship between vegetable subgroups, glucose tolerance and insulin sensitivity.”