Food is a basic human need. We need to consume food from a variety of food sources to enable us to obtain calories and nutrients to allow our minds and bodies to function. Contemporary eating patterns and poor diets in Australia are a major risk factor for the development of heart disease, as well as other chronic diseases including type 2 diabetes and some cancers. Suboptimal dietary patterns also directly contribute to the risk of becoming overweight or obese, which are also significant risk factors for developing heart disease. For example, excessive consumption of processed animal products and diets high in saturated fats and refined sugar can increase risk for coronary artery disease (hardening of the heart arteries). Conversely, while plant-based diets have been considered to be heart healthy, strict veganism can lead to nutritional deficiencies and increase risk of anaemia and low bone mineral density. So, with the myriad of food options and dietary approaches at our disposal, what is the best approach to minimise the risk of heart disease?
Many studies have demonstrated that the traditional Mediterranean diet forms the foundation for a heart healthy diet. This diet is associated with lower risk for all-cause death and heart-related death, coronary artery disease, metabolic syndrome, diabetes, cognitive decline, neurodegenerative diseases (including Alzheimer’s disease), depression, breast cancer and colorectal cancer. The traditional Mediterranean diet is rich in whole grains, vegetables, fruits, legumes, nuts, and seeds, but also includes moderate amounts of animal-based proteins like dairy, eggs, seafood, and other lean meats. Due to its proven heart health benefits, the Mediterranean diet has been endorsed by the National Heart Foundation (click here to download the National Heart Foundation Dietary Position Statement) as well as the 2019 American College of Cardiology/American Heart Association Guideline on the Primary Prevention of Cardiovascular Disease.
A recent review article in the Journal of American College of Cardiology reviewed the body of evidence regarding the human diet that may lead to best overall heart health outcomes. According to the authors, intermittent fasting (with a daily time-restricted 8 to 12 hour eating window), combined with a Pesco-Mediterranean diet may be the ideal diet to lower risk of heart disease.
A Pesco-Mediterranean diet is essentially the same as a Mediterranean diet, but with a greater importance placed on the fish and seafood components of the diet. According to this review, eating seafood in place of red meat and poultry leads to a 34% reduction in risk of dying from coronary artery disease, likely because of the omega-3 fatty acids in fish. Eggs, another satiating and healthy substitute for processed meats are allowed in the Pesco-Mediterranean diet, preferably less than 5 yolks per week (limitless egg whites can be consumed). While there is no clear evidence regarding the role of dairy products in heart disease risk, they form part of this diet, but low-fat yogurt and cheeses are preferred, while butter and hard cheese are discouraged due to their high concentration of saturated fats and salt. Instead, the Pesco-Mediterranean diet recommends extra-virgin olive oil which has been proven to lower bad (LDL) cholesterol and increase good (HDL) cholesterol. For snacks, the Pesco-Mediterranean diet recommends consuming tree nuts, such as almonds, cashews, walnuts, and hazelnuts, which have been proven to lower heart disease risk by 28%. Preferred beverages are water (still or carbonated) and unsweetened coffee or tea.
Intermittent fasting, or time-restricted eating, is a method of eating that has been studied extensively in the last few years. It essentially limits the window during which calories can be consumed. Intermittent fasting improves multiple aspects of heart health, including blood pressure; resting heart rate; levels of good and bad cholesterol, triglycerides, glucose, insulin; and insulin resistance. In addition, it reduces markers of inflammation and oxidative stress that are associated with atherosclerosis (hardening of the heart arteries). Although we do not yet fully understand the exact mechanism by which intermittent fasting leads to these beneficial effects, it is felt metabolic switching and cellular stress resistance play a role.
My view is that theoretically, the Pesco-Mediterranean diet combined with time restricted eating is a safe, sensible, and healthy way of eating to minimise the risk of developing heart disease. However, before we can proclaim that this exact approach is definitively the ideal way to optimise heart health, we need to await the result of future controlled prospective trials comparing this approach with other diets that examine long-term heart health outcomes. Furthermore, in my experience, many people find it difficult to consume fish and seafood regularly, whether it be due to palatability, availability, or cost. Nonetheless, I recommend low-mercury fish, such as salmon, trout, and anchovies (without the pizza!), all of which are naturally high in omega-3 fatty acids, as well as scallops, lobster, oysters, and clams which are not as high in omega-3 fatty acids but are low in mercury, a high level of which is theoretically associated with adverse neurocognitive outcomes. Beyond the Pesco-Mediterranean diet, I also remind patients that limiting salt (sodium) in our diet can also lower blood pressure, as well as limiting sugar and carbohydrates can lower blood sugar levels to prevent or help control diabetes (high sugar levels).
Finally, I always emphasise to patients that diet is only one line in our defence to minimise our risk of heart disease – we must not forget regular exercise, avoiding smoking, adequate sleep, managing stress, limiting alcohol consumption and regular heart health checks with our GP.
A Pesco-Mediterranean Diet with Intermittent Fasting: JACC Review Topic of the Week. J Am Coll Cardiol 2020 Sep 22; 76(12):1484-1493, JH O’Keefe, N Torres Acosta, EL O’Keefe et al.