What is the optimal diet for a healthy heart?
Cardiovascular disease (CVD) is the leading cause of death globally. Every year, 17.3 million people will die from CVD, and in the UK alone over a quarter of deaths (26 per cent) are due to CVD. [1, 2]
Diet plays a major role in reducing the risk of, and preventing CVD. This in itself is not news. However, questions over the ideal diet for optimal cardiovascular health continue to stir debate and generate headlines.
Recently, data was presented at the ESC2016 in Rome, Italy, which stated that the Mediterranean Diet was not only beneficial in healthy subjects, but was associated with a reduced risk of death in patients with a history of cardiovascular disease. 
A large-scale epidemiological study, the MOLI-SANI study, randomly recruited 25,000 adults from the Italian region of Molise. Of these, 1197 had a history of CVD at enrollment. Researchers found that high adherence to the Mediterranean diet – high consumption of vegetables, fish, fruits and nuts and monosaturated acids, with reduced saturated acids – was associated with 37 per cent lower risk of death compared to those with a low adherence to the diet. 
This research is in-line with data from the Karolinska Institutet, Sweden and published in the Journal of Internal Medicine, which highlights the risk of eating too much processed red meat – ham, sausages, bacon, frankfurters or salami, for example. According to this study, eating just 50 grams of processed red meat every day was associated with an increased risk of death of 24 per cent, and an increased risk of diabetes by 32 per cent. 
Until recently, research pointed towards a diet high in fruit and vegetables, and low in saturated fats as the optimal diet for optimal cardiovascular health. However, as always things are not so straightforward.
A recent meta-analysis, published in Open Heart Journal looks at data which was used to influence both US and UK dietary guidelines, and questions the relationship between dietary fat intake and coronary heart disease. 
National dietary guidelines in the US and UK were released in 1977 and 1983, respectively, both of which were heavily focused on reducing dietary fat – “overall fat consumption by 30 per cent total energy intake, and total saturated fat to 10 per cent total energy intake.”
However, this meta-analysis – which included 62,421 subjects from 10 dietary trials – did not identify any direct relationship between total or saturated fat intake and CHD events or death. 
The researchers conclude that: “RCT evidence currently available does not support the current dietary fat guidelines,” adding that: “The evidence per se lacks generalisability for population-wide guidelines.”
These results are echoed by a recent ecological study published in Food & Nutrition Research, where researchers were unable to find any association with CHD and saturated fat, but instead associated increased CVD risk with carbohydrate-rich diets (i.e., consumption of carbohydrates with high glycemic index/load). 
We have seen over the past four decades that people have shifted away from consuming saturated fats and switched to eating more carbohydrates. And this, according to statistical data published in Nutrition correlates with the steady rise in obesity that we have seen over the past 40 years. 
In the face of such conflicting data, it is difficult to ascertain exactly what the optimum diet is for good cardiovascular health. However, at the very least, it is clear that current dietary guidelines are in need of urgent review.
- Bonaccio M, Di Castelnuovo A, Constanzo S, et al., Higher adherence to Mediterranean diet is associated with lower risk of overall mortality in subjecrs with cardiovascular disease: prospective results from the MOLI-SANO Study. European Heart Journal (2016) 37 (Abstract Supplement); 555-6.
- Harcombe Z, Baher JS, Di Nicolantonio JJ, Grace F, Davies B. Evidence from randomized controlled trials does not support current dietary fat guidelines. A systematic review and meta-analysis. Open Heart 2016; 3: doi: 10.1136/openheart-2016-000409
- Grasgruber P, Sebera M, Hrazdira E, Hrebickova S, Cacek J. Food consumption and the action statistics of cardiovascular diseases: An epidemiological comparison of 42 European countries. Food & Nutrition Research 2016, 60: 31694 – http://dx.doi.org/10.3402/fnr.v60.31694.
- Cohen E, Cragg M, DeFonseka J, et al., Statistical review of US macronutrient consumption data, 1965–2011: Americans have been following dietary guidelines, coincident with the rise in obesity. Nutrition 2015; 31 (5): 727-32.