Plant and animal protein for older adults? New insights from a multi-cohort study

Aim

The study was conducted as animal protein has historically been used to address malnutrition despite a potential unintended increase in risk of other chronic diseases as a result.

A direct comparison with plant-based proteins was conducted to elucidate if these sources are as effective at preventing malnutrition, while having the added benefit of not increasing chronic disease risk.

Method

This cohort study was conducted on two Spanish groups of community-dwelling older adults sourced from the Senior-ENRICA data.

The sample encompassed 2965 people. Data were collected on socio-demographic, lifestyle, and morbidity variables via telephone interviews.

Diet histories were collected by trained researchers who also conducted physical examinations.

Malnutrition was measured through involuntary weight loss, low BMI and reduced muscle mass as well as reduced food consumption and inflammation using the Global Leadership Initiative on Malnutrition criteria.

Key findings

Descriptive outcomes

The study participants varied based on type of protein consumed and 65.7% of the total protein consumed by the populations was animal protein:

• Those with higher animal-protein intake were more likely to be younger, smoke tobacco and have lower energy intake.

• Higher plant-based protein intake was associated with lower diabetes risk, higher physical activity and eating more fruits and vegetables.

The main animal sources in descending order were meat, dairy, fish and eggs. The plant-based protein sources were cereals, legumes and nuts.

Main results

Higher protein intake is associated with improvements in nutritional status. Odds ratios per 0.25g/kg/day were 1.15 for animal protein and 1.77 for plant-based protein.

The researchers highlight that previous methodologies to assess the biological value of protein may be biased towards animal-based proteins. For example, using raw food values rather than cooked and prepared food amino acid values.

In this study, essential amino acid requirements are above this threshold in the plant-based foods consumed.

• The clearest dose response relationship was observed when plotting plant-based protein with nutritional status.

• Only vegetable protein was found to be linked to inflammation-related improvements in nutritional status.

• Logistic regression shows replacing 0.25g/kg/day of animal protein with plant-based protein is associated with significant improvements in nutritional status.

Meat and fish did not significantly increase nutritional status, whereas cereals and legumes had a particularly positive impact.

Interestingly, in the study participants with poor dentition or dentures, meat intake was even less associated with nutritional status improvement, potentially due to delayed nutrient absorption and digestive capabilities.

The symbiotic nature of plant- and animal-based protein was particularly notable in the Seniors-ENRICA 1 cohort in which the positive impact of plant-based protein was stronger in those participants who had higher animal-protein intake.

The results are likely generalisable to an extent in UK populations as the intake of protein from plant-based sources is in line with the population average (34% of total protein intake).

Conclusion

In this study of community-living, older adults, higher consumption of animal AND plant-based proteins were associated with improvements in nutritional status.

This has implications for previous dietary recommendations for the elderly.

Of particular note is the observed benefit of a combination of animal-protein sources in the diet with plant-based alternatives.

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