Focus on nutrition at ESC Congress 2021: What’s in – and out of – a healthy diet?

Introduction

Research into the foods we eat and nutritional supplements that we take always generate attention at ESC Congress. In addition to our scientific interest, it may be that we are all secretly hoping that the foods we (guiltily) love will turn out to be heart healthy! This year’s ESC Congress was no different, so we thought we’d review some of the nutritional research presented in 2021.

What’s in – and out of – a healthy diet?

Some foods and additives have long generated controversy. Take saturated fats. The 2021 ESC Guidelines on cardiovascular disease prevention in clinical practice (1) recommend < 10% of daily energy intake should come from saturated fats, but are all sources the same? Dr. Rebecca Kelly of the Nuffield Department of Population Health, University of Oxford, UK, and colleagues analysed data from the dietary assessment of 114,285 UK Biobank participants who had no cardiovascular conditions (CVD) at time of assessment. Participants were followed over a median of 8.5 years. They found no significant associations between saturated fatty acid (SFA) intake and total CVD, ischaemic heart disease (IHD) and stroke. SFA from meat (differentiated from poultry, fish and dairy sources) was positively associated with total CVD (hazard ratio [HR] per each 5% of energy: 1.19; 95% CI 1.05 – 1.35), IHD (HR 1.21; 1.05 – 1.39) independent from other lifestyle and CVD risk factors. Dairy sources of SFA were inversely related to IHD risk (HR 0.89; 0.82 – 0.96). However, the estimates of both sources of SFA were non-significant after adjustment for BMI.

In a press release, Dr. Kelly stated that it was not possible to determine if there was a specific impact of SFA from meat on BMI, or whether those with a higher BMI ate more meat. Interestingly modelling replacement of 5% energy intake from meat with carbohydrates from whole grains, fruit and vegetables reduced risk of stroke in multivariate analysis and after adjusting for BMI and LDL-C. (2) 

Another source of controversy in recent years has been the amount of salt in diets that should be recommended. The Salt Substitute and Stroke Study (SSaSS) was an open-label, cluster-randomised trial that recruited 20,955 participants with a history of stroke or those aged 60 or older with high blood pressure from 600 villages in rural China. Each village was randomly assigned to use regular salt or to use a salt substitute. Follow-up was for a mean of 4.74 years and showed a 14% reduction in stroke (rate ratio 0.86, 95% CI 0.77 – 0.96, p = 0.006), and a 13% lower rate of major CVD events (rate ratio 0.87; 95% CI 0.82 – 0.95; p < 0.001). Serious adverse events due to hyperkalemia did not differ between the two groups.

Professor Bruce Neal, principal investigator from George Institute for Global Health, Sydney, Australia, noted that the results demonstrated a practical way of achieving change in salt consumption that was effective in decreasing cardiovascular events and low cost. The study has been published in the New England Journal of Medicine (3) and was presented at the hot line session (4). 

In our busy lives, it is easy to reach for prepared foods, but we should be mindful of whether these are processed foods or ultra-processed foods. Ultra-processed foods are those that have additional flavours, stabilisers, preservatives and chemicals that you wouldn’t find in your kitchen. Pre-packaged meals, sweetened cereals, crisps, soft drinks and baked goods are ultra processed. In an analysis of data from the ATTICA study in Greece, 2020 participants without CVD at baseline were assessed for adherence to a Mediterranean type diet (emphasis on fruit, vegetables and whole grains) and for consumption of ultra-processed food. Over a 10-year follow-up, individuals consuming more ultra-processed foods had an increased incidence of CVD. Each additional weekly serving was associated with a 10% higher likelihood of developing CVD (HR 1.10; 95% CI 1.02 – 1.21; p = 0.04) within the decade. This association was attenuated by a moderate to high adherence to a Mediterranean heart healthy diet and was no longer significant for those with high adherence. Those with a low score on adherence, however, had a 19% greater risk of CVD (HR per additional serving 1.19; 95%CI 1.12–1.25;p=0.02). The study was led by Dr. Matina Kouvari of Harokopio University of Athens, Greece. (5)

Another health benefit came from light to moderate consumption of coffee. Dr. Judit Simon, of the Heart and Vascular Centre, Semmelweis University, Budapest, Hungary, reported an analysis of 468,629 participants of the UK Biobank without heart disease at recruitment. In multivariable models adjusted for other cardiovascular risk factors, light to moderate coffee drinking was associated with a 12% reduction in all-cause death, 17% reduction in CVD death, and 21% lower risk of stroke compared to non-coffee drinkers over the 11-year follow-up. Although higher intake of coffee was not associated with the same benefit, it also was not associated with adverse outcomes. Intriguingly, the investigators found differences in cardiac structure and function in 30,658 participants that underwent cardiac magnetic resonance imaging due to coffee consumption. Compared to those without regular coffee consumption, people who drank coffee daily had healthier sized and better functioning hearts.

The investigators concluded that drinking up to three cups of coffee per day was associated with positive benefits, and that some of the effect may be due to positive change in cardiac structure and function. (6)

Conclusion

These are just a few of the abstracts presented that focused on nutrition. These studies highlight the importance of healthy diets and that a few changes can often have profound effects on cardiovascular disease. When reviewing nutritional studies it is important to consider overall diet quality and adherence to healthier options. Eating a healthy Mediterranean diet attenuated some of the detrimental effects of ultra-processed food and replacing only 5% energy from meat intake with whole grains, vegetables, and fruits reduced stroke risk. Obviously more research is needed in many areas, but a Mediterranean-type diet has never been shown to be anything other than beneficial.