New research at McGill University in collaboration with the London School of Hygiene & Tropical Medicine provides compelling evidence that partially substituting animal with plant protein foods can increase life expectancy and decrease greenhouse gas emissions. Importantly, it also suggests that benefits depend on the type of animal protein being replaced.

The study, published in Nature Food, drew data from a national nutrition survey to analyze Canadians’ dietary records. The study modeled partial replacements (25% and 50%) of either red and processed meat or dairy with plant protein foods like nuts, seeds, legumes, tofu, and fortified soy beverages, on a combination of nutrition, health, and climate outcomes.

Small dietary changes, big impact on carbon footprint

Red and processed meat and dairy are the primary contributors to Canada’s diet-related greenhouse gas emissions, as evidenced in a previous study. Remarkably, this study found a person’s diet-related carbon footprint plummets by 25% when they replace half of their intake of red and processed meats with plant protein foods. On the other hand, dairy substitutions showed smaller reductions of up to 5%.

“We show that co-benefits for human and planetary health do not necessarily require wholesale changes to diets, such as adopting restrictive dietary patterns or excluding certain food groups altogether but can be achieved by making simple partial substitutions of red and processed meat, in particular, with plant protein foods,” explains Olivia Auclair, first author and recent PhD graduate in McGill’s Department of Animal Science.

Sex gap in plant-based health benefits

Diets high in animal products are known to increase the risk of heart disease, diabetes, and certain cancers. In this study, researchers estimated that if half of the red and processed meat in a person’s diet was replaced with plant protein foods, they could live on average, nearly nine months longer, stemming from a reduced risk of chronic disease.

When broken down by sex, males stand to gain more by making the switch, with the gain in life expectancy doubling that for females. In contrast, partially replacing dairy with plant protein foods led to smaller gains in life expectancy and was accompanied by a trade-off: an increased calcium inadequacy by up to 14%.

“I hope our findings will help consumers make healthier and more sustainable food choices and inform future food policy in Canada,” says senior author Sergio Burgos, Associate Professor in McGill’s Department of Animal Science and scientist at the Research Institute of McGill University Health Centre.

As more people seek sustainable and health-conscious diets, the study’s findings serve as a guide, empowering individuals to make informed choices that benefit both personal well-being and the planet.

“Increasing the consumption of plant-based foods alongside reductions in red and processed meat would have considerable benefits for health and the environment and would involve relatively small changes in diets for most people in Canada,” says Patricia Eustachio Colombo, co-author and Honorary Research Fellow at the London School of Hygiene & Tropical Medicine’s Centre on Climate Change & Planetary Health.

About the study

“Partial substitutions of animal with plant protein foods in Canadian diets have synergies and trade-offs among nutrition, health and climate outcomes” by O. Auclair et al. was published in Nature Food.

Could semaglutide help obese patients with heart failure?

HFpEF – commonly known as ‘hef-pef’ – refers to heart failure with preserved ejection fraction, a condition for which no treatment has hitherto been available. Current thinking suggests that obesity may be a causative factor in HFpEF rather than a co-morbidity. “In the U.S. about 80 percent of patients with HFpEF also have obesity”, says Ms Ruszala Therefore, STEP-HFpEF was designed to investigate whether treating obesity in such patients had an impact on their heart failure.

The trial had dual primary endpoints comprising quality of life (using the Kansas City Cardiomyopathy Questionnaire (KCCQ) score) and weight loss.

How semaglutide impacts HFpEF

“The findings [of the STEP-HFpEF trial] were very definitive”, says Ms Ruszala. There was an eight-point difference in the KCCQ score. (A minimum four-point difference is clinically significant). “The patients who were on semaglutide felt much better, had far, far [fewer] symptoms and were able to do more in their daily life with increased exercise capacity”, she explains. In addition, there was an 11 percent greater body weight loss in the semaglutide group compared with the placebo group. Both endpoints were statistically significant. Furthermore, the hierarchical secondary endpoints were all met.

Previous trials of weight loss combined with exercise have shown benefits in quality of life but not to the same extent as those seen with semaglutide. Moreover, “the weight loss itself wasn’t significant enough in many of the previous trials, so there was something extra seen in [this trial] that wasn’t previously”, says Ms Ruszala.

Semaglutide for prevention or cure of HFpEF?

The results of the STEP-HFpEF trial point towards routine use of GLP-1 agonists in heart failure but this has to be balanced against conflicting guidelines and cost pressures in the NHS. “We know there’s benefit [from] GLP-1s in kidney disease, we know there’s benefit [from] GLP-1s in type 2 diabetes; we now know there’s benefit in heart failure as well”, says Ms Ruszala.

The new ESC guidance (European Society of Cardiology guidance) for heart failure or heart disease and diabetes that was launched in August [2023], already says anyone who has heart failure and type 2 diabetes should be given dual therapy with an SGLT-2 (sodium-glucose co-transporter-2 inhibitor) and a GLP-1 agonist. However, this is not yet in the UK heart failure guideline and this presents UK cardiologists with a dilemma.

Currently the UK approach to the use of semaglutide in heart failure is different from the approach elsewhere in Europe. “I think it goes back to the prevention versus cure [question]. At the moment our guidance is set up as cure …… [but] this kind of medicine is preventative. If you give semaglutide or another GLP-1 to somebody early in their diabetes pathway, early in their HFpEF pathway, the likelihood is that they will be much better, fitter and [generally well] for much longer” says Ms Ruszala.

However, semaglutide is not available in the UK currently and it’s not likely to be available in the UK until 2024. Much can be achieved with the existing treatment protocols and there should be a strong focus on optimising treatment with the available medicines, she suggests.

About Vicky Ruszala

As a specialist cardiology pharmacist, a large part of Vicky Ruszala’s work involves optimising medications for heart failure. She works on the specialist cardiology ward and also has two heart failure clinics each week.  She is an independent prescriber and has her own patient caseload.

Read and watch the full series on our website or on YouTube.

The STEP-HFpEF trial excluded people with type 2 diabetes but there are ongoing trials with glucagon-like peptide 1 (GLP-1) agonists in patients with obesity, type 2 diabetes and heart failure with preserved ejection fraction (HFpEF).  Nevertheless, the results of the trial add to the understanding of cardio-renal-metabolic disease. “We know there’s benefit [from] GLP-1s in kidney disease, we know there’s benefit [from] GLP-1s in type 2 diabetes; we now know there’s benefit in heart failure as well”, says Ms Ruszala.

As a result, “cardiologists are now looking to say, well actually, anybody who’s got a BMI over 30 – because that was one of the cutoffs in the trial – should be given a GLP-1 agonist.   …..In the new ESC guidance (European Society of Cardiology guidance) for heart failure or heart disease and diabetes that was launched in August [2023], it already says anyone who has heart failure and type 2 diabetes should be given dual therapy with an SGLT-2 (sodium-glucose co-transporter-2 inhibitor) and a GLP-1”, she says. However, this is not yet in the UK heart failure guideline. “So, we have a lot of cardiologists that are looking to Europe and trying to do what Europe is doing whilst living in an NHS environment”, she says.

In theory, the trial paves the way for treatment of a group of patients who would derive significant benefit from receiving a GLP-1 agonist. Ms Ruszala’s previous experience as specialist pharmacist in diabetes taught her that it was “a huge struggle” to persuade prescribers to use a GLP-1 agonist for type 2 diabetes because of costs and organisational issues.

Should GLP-1s be routine treatment in heart failure?  

There are still many questions to be answered about the role of GLP-1 agonists. Ms Ruszala explains: “The difficulty we have in the NHS is the cost and …. the supply chain issue at the moment, you know. Let’s not stand aside from the fact that semaglutide is actually not available in the UK currently – it’s not likely to be available in the UK until 2024. So, we are sitting in a place where the science says it will be great and everybody kind of wants to do it and we know that we probably should do it. We have guidelines that say we shouldn’t, because we have nothing for HFpEF. We have [semaglutide for] type 2 diabetes but only if you’ve tried four or five other things [first].”

Currently the UK approach to the use of semaglutide in heart failure is different from the approach elsewhere in Europe. “I think it goes back to the prevention versus cure [question]. At the moment our guidance is set up as cure – when this has happened treat like this. [But] this kind of medicine is preventative. If you give semaglutide or another GLP-1 to somebody early in their diabetes pathway, early in their HFpEF pathway, the likelihood is that they will be much better, fitter and [generally well] for much longer throughout their journey.  So, we’re talking about more preventative, social kind of engineering to allow people to lose weight and thereby exercise more, … have less symptoms and …. be more productive”, she explains.

Talking to patients

Many patients will have seen headlines about the use of semaglutide in patients with heart failure and may be wondering if it is a suitable treatment for them. Ms Ruszala suggests there are some key points that could be included in conversations about this:

• This is the first trial of its kind and others will follow e.g. the SUMMIT trial which is to assess the efficacy and safety of tirzepatide in participants with HFpEF and obesity
• At present semaglutide is unavailable in the UK
• There should be a focus on optimising treatment with the available medicines. “Make sure people are on SGLT2 Inhibitors because they aid weight loss – they also treat diabetes like the GLP-1s”, says Ms Ruszala. “What pharmacists should be doing is encouraging patients to take control of themselves from a …. lifestyle perspective and supporting that change. Also ….. thinking about – ‘what can I use that I’ve currently got?’ – making sure people are on maximum dose ACE-inhibitors, making sure people are on beta-blockers if they’ve got a fast heart rate, getting an SGLT2 inhibitor in. All of those drugs that we currently have access to will still be of huge benefit”, she emphasises.

“Let’s use this as a good time to start doing all the other things and getting everything else better”, she says.

About Vicky Ruszala

As a specialist cardiology pharmacist, a large part of Vicky Ruszala’s work involves optimising medications for heart failure. She works on the specialist cardiology ward and also has two heart failure clinics each week.  She is an independent prescriber and has her own patient caseload.

Read and watch the full series on our website or on YouTube.