A new study has found regularly swapping red meat with legumes, nuts and seeds, or wholegrains (or a combination of these) may lower the risk of type 2 diabetes in Australian adults (1).

It found replacing one serve of red meat (65g of cooked meat) each day with one serve of plant foods (such as a handful of nuts, or ½ cup of legumes), may result in higher insulin sensitivity – which typically predicts lower type 2 diabetes risk.

Our findings support advice to prioritise plant-based sources of protein (1).

The research results coincide with the review of Australia’s (2013) dietary guidelines. The National Health and Medical Research Council, in charge of the review, has identified ‘protein-rich foods’ as a priority topic.

About the research

The modelling study, just published in the British Journal of Nutrition, involved 783 participants from the long-running Childhood Determinants of Adult Health cohort study.

Dietary data was collected, over a 13-year period at three different time points, to calculate the average daily intake (in standard serves) of each food group. Insulin sensitivity was estimated from fasting glucose and serum insulin concentrations at one of the time points (in 2017–2019, when the study participants were 39-49 years old).

The researchers then used statistical modelling to estimate the effect, on insulin sensitivity, of replacing red meat with plant-based alternatives.

They adjusted for potential confounders, including family history of diabetes, physical activity, and energy (kilojoule) intake.

What did the study find?

• Regularly replacing red meat with plant foods (legumes, nuts/seeds, and wholegrains) – either in combination or on their own – was linked with higher insulin sensitivity.

• Of the plant foods modelled, the estimated effect on insulin sensitivity was largest when nuts and seeds replaced red meat.

• The combination of antioxidants, phytochemicals, unsaturated fatty acids, and fibre in legumes, nuts and seeds, and whole grains are likely to play a role in the estimated effect on insulin sensitivity.

• Abdominal obesity (as measured through waist circumference) may also be an important mediator in this relationship.

• The modelling estimates were similar, but less precise, when replacing processed meat with plant protein foods.  

Did you know? A large US-based study, published in 2023, found that replacing one serve per day of total red meat with nuts and legumes was linked with a 30% lower risk of type 2 diabetes (2).

What quantities and serve sizes were used?

The researchers initially modelled a one serve (65g) per day lower intake of red meat, in parallel with a one serve per day higher intake of legumes (75g), nuts and seeds (30g), or whole grains (such as 40g of whole grain bread).  

They also halved the standard serve size of each food group to explore more modest substitutions. This showed that the higher estimate of insulin sensitivity with a one serve per day replacement, persisted with a 0.5 serve per day replacement, for each food group.

When replaced with specific plant foods (legumes, nuts and seeds, or whole grains), even modest reductions in red meat may contribute to lower type 2 diabetes risk (1).

Table 1: Standard serves sizes of each food group modelled

Did you know? Just 2% of Australians eat 30g of nuts a day, with the mean intake just 4.6g (3).

Current Australian diets lack plant protein

In the average Australian diet, for adults aged 19-50 years, red meat and poultry, fish/seafood, and eggs contributed 87% to the total servings consumed within the ‘meat and alternatives’ or ‘protein’ food group (with 73% coming from red meat and poultry) (4).

Yet, plant-based protein rich foods (nuts and legumes) contributed just 13%.

How to eat more plant proteins:

• Snack on nuts between meals, and opt for a meat-free lunch
• Alter the proportion of red meat (less), and legumes or nuts (more), in a recipe
• Incorporate legumes, like lentils and beans, into meals at least 2-3 times per week
• Swap one or more meat meals a week for a meal based around plant protein foods
• Choose wholegrain foods like rolled oats, brown rice, wholegrain bread, and quinoa
• Add seeds such as sunflower, pumpkin or chia to salads and trail mixes
• Enjoy a healthy handful of nuts each day

In 2021, the global prevalence of diabetes for adults (aged 20-79 years) was 10.5% (537 million) (5). In Australia, almost 1.9 million people have diabetes (6). Type 2 diabetes, which is largely preventable, accounts for 85–90% of all cases – and is increasing each year.

The bottom line:

The findings support prioritising plant-based sources of protein, which are vastly under-consumed in Australia, to help prevent type 2 diabetes. Every day dietary swaps are a simple place to start.

And more broadly, the current review of Australia’s dietary guidelines is an opportunity to:

1. Re-emphasise diversity and variety within food groups
2. Prioritise plant-based protein foods
3. Elevate nuts as important to eat every day (minimum 30g daily).