Plant protein consumption in midlife promotes healthy ageing

Aim

The study aimed to assess the association between midlife protein intake and healthy ageing among 48,762 female participants from the Nurses’ Health Study cohort aged <60 years old in 1984.

Method

Protein intakes from animal, dairy and plant sources were calculated based on dietary assessment data from food frequency questionnaires.

Healthy aging, defined as being free from 11 major chronic diseases, having no impairment in memory or physical function and being in good mental health, was assessed 30 years later through follow-up questionnaires.

The association between midlife protein intake and healthy aging was adjusted for several covariates including education level, marital status, body height and weight, physical activity, cigarette smoking, medication use, health status, race, and dietary quality.

Key findings

Consumption of plant protein is associated with healthy ageing

Amongst the participants, 7.6% (3721) achieved healthy ageing.

Overall, protein intake and especially the consumption of plant protein was significantly associated with higher odds of healthy ageing.

Specifically, for each 3% increase in animal, dairy, and plant protein intake, the odds of healthy ageing increased by 7% (95% CI: 2%–11%), 14% (95% CI: 6%–23%), and 38% (95% CI: 24%–54%) respectively.

When examining individual domains of healthy aging, plant protein intake stood out compared to dairy and animal protein.

Total and animal protein intake were linked to an increased chronic disease risk, while dairy and plant protein intake were associated with a lower risk.

While both animal protein and plant protein were associated with higher odds of being free of physical limitations, the association was stronger for plant protein, with 5% higher odds (95% CI: 2% - 9%) for animal proteins versus 41% higher odds (95% CI: 27% - 57%) for plant proteins.

Additionally, only plant protein was significantly associated with 16% higher odds of good mental status.

Effects of substituting dietary animal protein, carbohydrates, and fat with plant protein

The study further examined the impact of replacing 3% of energy intake from dietary carbohydrate or fatty acids with an isocaloric intake of dairy, animal, or plant protein on the odds of healthy ageing.

Substituting 3% of energy intake with plant protein, in place of animal or dairy protein, carbohydrate, or fat, was associated with achieving healthy aging, resulting in odds ranging between 22% and 58% higher.

Factors that could explain such association include the positive nutrient profile of plant protein sources (such as dietary fibre, micronutrients, and polyphenols), and the association between plant protein consumption and lower cardiometabolic risk factors (such as LDL cholesterol, blood pressure, and insulin sensitivity).

Conclusion

In a large cohort of female nurses, higher dietary protein intake in midlife, especially plant protein, is associated with higher odds of healthy ageing, and with several domains of positive health status such as lower risk of chronic diseases, good physical function and good mental health status.

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