Current thinking suggests that a diet high in protein is beneficial for health, boosting metabolism, and aiding weight loss. However, new research carried out at Brown University Memorial Hospital, Rhode Island, has revealed that for older women a high-protein diet may be more harmful than helpful.
The researchers came to their findings by analysing data of 103,878 post-menopausal women aged 50-79 years who were part of the Women’s Health Initiative (WHI). As part of the survey, participants were required to complete a food frequency questionnaire that assessed their daily intake of around 125 different food items. The researchers looked at the total daily protein intake, as well as the total amount of daily protein consumed from meat and vegetables.
As self-reported dietary data can be inaccurate, the researchers also used biomarker data to get a more reliable indication of protein intake. This involved assessing subjects' urinary nitrogen and doubly labelled water levels - a measure of metabolism.
All women were free of heart failure at study baseline, and heart failure development was monitored until 2005.
A total of 1,711 of the women in the study developed heart failure, the team reports.
Compared with women who had low total protein intake, those who had a higher total protein intake were found to be at much greater risk of heart failure. The risk was greatest among women who consumed most of their protein from meat.
The results remained after accounting for age, race/ethnicity, education level, high blood pressure, coronary heart disease, anaemia and arterial fibrillation.
The researchers did uncover an association between high intake of vegetable proteins and lower risk of heart failure, but when the team accounted for body mass index (BMI), this result was not statistically significant.
The team warns that the findings should be interpreted with caution and further research is required, but they do suggest a high-protein diet may be linked to heart failure.
Commenting on the findings, study co-author Dr Mohamad Firas Barbour said: "Higher calibrated total dietary protein intake appears to be associated with substantially increased heart failure risk while vegetable protein intake appears to be protective, although additional studies are needed to further explore this potential association."
The findings of the research were recently presented at the American Heart Association’s Scientific Sessions 2016, held in New Orleans, USA.