What is heart disease?
What we usually call heart disease is a common term for cardiovascular disease (CVD) which includes several diseases of the heart or blood vessels. The main types of CVD are coronary heart disease, stroke and peripheral arterial disease.
- Coronary heart disease (CHD) occurs when the flow of blood into the heart is limited or blocked by a build-up of plaques in the coronary arteries (two major blood vessels supplying the heart with oxygen-rich blood). Restricted blood supply to the heart can cause angina (chest pain) and if the supply is completely blocked it causes collapse of the heart muscle - a heart attack.
- A stroke is a condition that occurs when the blood supply to a part of the brain is severely limited or blocked. If the brain cannot get enough oxygen through blood supply, it can cause brain damage very quickly and may result in death.
- Peripheral arterial disease (or peripheral vascular disease) occurs when there's a blockage in the arteries supplying blood to the limbs, usually the legs. The most common symptom is leg pain when walking or exercising the legs.
These blockages occur as a result of atherosclerosis (where arteries become narrower because of fatty build-ups known as plaques or atheroma). Plaque is made of cholesterol, fatty substances, cellular waste products (as white blood cells attach themselves to the cholesterol deposits in an attempt to dissolve them), calcium and fibrin (a clotting material in the blood).
The plaques cause affected arteries to harden and narrow, thus restricting blood flow. If a plaque tears away or ruptures or if an artery becomes too narrow to function properly, it can block the blood supply to vital organs and cause any of the above conditions.
Risk factors for heart disease include:
- High blood pressure (hypertension)
- High blood cholesterol levels
- Physical inactivity
- Being overweight or obese
- Family history of heart disease
Listed below are a selection of studies that have investigated the effects of diet on heart health:
- The EPIC study analysed data on CVD from the British population to examine whether vegetarians have a lower risk of the disease than omnivores, and it brought predictable results (Crowe et al., 2013). Vegetarians had on average much healthier weight, cholesterol levels and blood pressure – all crucial risk factors for CVD – and as a result, their risk of CVD was 32 per cent lower that in the omnivore population.
- In terms of blood cholesterol, vegans had the lowest levels compared to vegetarians and meat-eaters (Bradbury et al., 2014). This could be to a small degree attributed to weight differences but diet composition is by far the biggest factor.
- A previous EPIC analysis looking only at the blood pressure of British participants showed that vegans have the lowest and meat-eaters the highest blood pressure; vegetarians and pescaterians were in the middle (Appleby et al., 2002). Accordingly, vegans had the lowest risk of suffering from hypertension. The same conclusion was reached in the Adventist Health Study 2 that was following American and Canadian subjects (Pettersen et al., 2012). In this study, vegans had 63 per cent lower risk of hypertension than meat eating participants.
- Huang et al. (2012) analysed seven studies with a total of 124,706 participants. They found that vegetarians have a significantly lower CVD mortality – their risk was 29 per cent lower than in omnivores.
- And when analysing data from studies on diet and stroke, He et al. (2006) observed that the higher the intake of fruit and vegetables, the lower the risk of stroke. People who consumed more than five portions a day had a 26 per cent lower risk of stroke.
- To test whether a low-fat wholesome vegan diet can achieve measurable differences in CVD risk factors over a period as short as one week, McDougall et al. (2014) assigned volunteers on a residential program where they were tested before and after and all their meals were prepared by professionals. The participants were not limited in their food intake. After one week on this vegan diet, they achieved weight loss, decrease in cholesterol levels and blood pressure, and better blood sugar control. In conclusion, just seven days of this lifestyle achieved substantial favourable changes in common risk factors for CVD and metabolic diseases.
Lifestyle changes have been shown to significantly improve the health of those who are at risk of, or already have CVD. Here is a selection of studies supporting this:
- Dr Ornish his team performed a five-year study that involved diet and lifestyle changes (Ornish et al., 1998). Patients with moderate to severe CVD were assigned to an intensive lifestyle change group or to a no-change control group. The lifestyle change group were asked to consume a low-fat almost vegan diet, do moderate aerobic exercise, practice stress management and stop smoking. In the vegan group the plaques in the arteries were markedly reduced and the blood flow improved, they lost excess weight, and LDL ('bad') cholesterol levels decreased by 40 per cent after one year – all without lipid-lowering medication. The arteries of the non-vegan control group continued to narrow.
- Dod et al. (2010) enrolled people with or at risk of CVD on a three-month program that required them to adopt a low-fat vegan diet, do three hours of moderate exercise a week and practice stress management. At the end of the study, the participants’ blood vessel function and blood flow had significantly improved, their cholesterol levels were reduced and their inflammatory markers significantly decreased.
- Dr Esselstyn’s purely plant-based approach to preventing and reversing CVD is internationally renowned and he has countless case studies proving the effectiveness of low-fat vegan diets. In an intervention study of 198 people with CVD, 177 adhered to a diet based on wholegrains, pulses (lentils, beans, soya, peas, chickpeas), vegetables and fruit (Esselstyn et al., 2014). Participants were also encouraged to take a multivitamin and vitamin B12 supplement, and to use flaxseed as an additional source of omega-6 and omega-3. Apart from animal-based foods, patients were also told to avoid added oils and processed foods that contain oils, avocado, nuts, sugary foods and drinks and excess salt. Of the 112 participants that reported angina at the beginning, 104 experienced improvement or resolution of symptoms during the follow-up period. 39 participants with severely affected (blocked) coronary arteries showed disease reversal, and 27 were able to avoid surgery that was previously recommended.
- A team of scientists from Harvard studied how diet impacts on heart attack survivors. Those who changed their diet and increased their fibre intake (moving towards a plant-based diet) after heart attacks had significantly higher chances of survival (Li et al., 2014). In particular, greater intake of fibre from wholegrains was found to be very beneficial. Increasing fibre consumption was also strongly associated with lower mortality from all causes, as well as cardiovascular disease. Patients who followed a low-carbohydrate diet high in animal protein and fat had a higher all-cause and cardiovascular mortality (Li et al., 2014). The study authors did not find any health benefits from adherence to a low carbohydrate diet.
- A review of studies on diets for people with/at risk of CVD or diabetes arrived at a conclusion that vegan diets are clearly better for improving cardiovascular health and blood sugar control (Trepanowski and Varady, 2015).
For references and more information, see The Incredible Vegan Health report. For practical guidance on how to improve your diet in order to help prevent or recover from heart disease see Viva! Health's heart disease resources.