Diet and heart disease risk

Cardiovascular disease, including coronary heart disease, is one of the leading causes of death worldwide. Although there is no single cause, an unhealthy diet is one of the contributing risk factors. Paying attention to what you eat — and choosing a variety of healthy foods from the main food groups — is one of the most important preventive measures you can take.

What heart disease is#

Heart disease results from the narrowing of the arteries that supply the heart with blood, through a process known as atherosclerosis. Fatty deposits (plaque) gradually build up on the inside of the artery walls, narrowing the space through which blood can flow to the heart. Atherosclerosis can start when you are young, so by middle age it can already be quite advanced.

Plaque build-up can be stable or unstable:

• Stable plaque that builds up too much narrows the arteries and can cause pain and discomfort because not enough blood reaches the heart — this is called angina, and it needs to be treated.
• Unstable plaque is inflamed and has a thin cap that is prone to cracking, letting blood come into contact with the fatty contents. Blood clots to seal the gap, but the clot can block the artery. This cuts off the heart’s oxygen supply and damages or kills heart cells — a heart attack.

Risk factors#

Some risk factors for heart disease cannot be changed, such as age, sex, ethnicity and family history. The good news is that there are plenty of risk factors within your control — including diet, body weight, blood pressure, cholesterol levels, diabetes management, physical activity, smoking, and depression and social isolation.

Some risk factors are connected. For example, cholesterol levels, blood pressure, body weight and diabetes management can all be affected by diet. So one of the best things you can do to reduce your risk of heart disease is to eat well and maintain a healthy weight.

Dietary fats and cholesterol#

Cholesterol is a fat that is crucial to many functions in the body and is part of every cell membrane. It is made by the body in the liver from the food we eat.

Blood fats that contain cholesterol include low-density lipoprotein (LDL) and high-density lipoprotein (HDL):

• LDL (“bad”) cholesterol can lead to plaque forming in the arteries.
• HDL (“good”) cholesterol helps remove cholesterol from the body and makes it harder for plaque to form.

Saturated fats#

Saturated fats (also called “bad fats”) tend to raise LDL cholesterol. Common sources include animal fats (butter, meat fat such as lard and dripping, fatty cuts of beef and lamb, chicken skin), coconut and palm oil, and processed foods like pastries and biscuits.

Although full-fat dairy foods such as milk, cheese and yoghurt contain saturated fat, this type of fat appears to have a fairly neutral relationship with heart health. Unflavoured milk, yoghurt and cheese can be part of most people’s diets, but those who need to lower their LDL cholesterol should choose reduced-fat versions.

Research also suggests eggs have a neutral relationship with heart health for most people — neither raising nor lowering heart disease risk. People who need to lower their LDL cholesterol, or who have type 2 diabetes, may be advised to limit eggs to around 7 per week.

Trans fats#

Like saturated fats, trans fats raise LDL cholesterol, but they also tend to lower HDL cholesterol, which makes them more damaging. Trans fatty acids form when vegetable oils are hydrogenated and hardened into some margarines, deep-frying oils and shortening, which the food industry uses in processed foods such as cakes, biscuits and deep-fried takeaway meals. Some trans fats also occur naturally in certain meats, butter and dairy products. Most table margarines today have very low levels of trans fats and are a preferred substitute for butter.

Healthier unsaturated fats#

Reduce your risk by replacing saturated and trans fats with unsaturated (“good”) fats. Substitute butter, coconut and palm oil, lard and dripping with oils made from seeds or plants — such as olive, avocado, sunflower, canola, safflower, peanut, soybean and sesame. Other good sources of unsaturated fats include unsalted nuts and seeds (including chia, tahini and linseed), olives and avocado.

Blood pressure and salt#

A diet high in salt is linked to high blood pressure (hypertension), which raises your risk of heart disease and stroke. Many people eat far more salt than they need (salt contains sodium and chloride). Most dietary sodium comes not from salt added at the table but from packaged and processed foods — even sweet foods that don’t taste salty can contain more sodium than you’d expect. To cut down, reduce processed and fast foods, check labels and choose lower-sodium products, and use herbs and spices for flavour instead of salt.

Foods important for heart health#

Eating a variety of foods supports good health and helps reduce the risk of disease. There is no single “magic” food, but some foods do appear to be important for heart health:

• Oily fish such as mackerel, sardines, tuna and salmon, which contain omega-3 fatty acids. These can lower triglycerides, raise HDL cholesterol, improve blood vessel elasticity and make the blood less likely to clot. Aim for oily fish at least once a week.
• Plant oils — those containing omega-6 (such as corn and safflower) and omega-3 (such as canola and olive oil) can help lower LDL cholesterol when used instead of saturated fats like butter.
• Fruit and vegetables, which provide fibre, potassium and other micronutrients including antioxidants, and are a source of folate. Folate helps lower blood levels of homocysteine, an amino acid linked to higher heart disease risk.
• Wholegrains and high-fibre foods. A diet high in fibre from wholegrain cereals is linked to lower LDL cholesterol. Soluble fibre (for example, from oats, legumes and barley) helps lower total cholesterol, and unrefined carbohydrates with a low glycaemic load help manage blood triglycerides and glucose.
• Legumes, nuts and seeds, which are good sources of plant protein, fibre, healthy fats and micronutrients.
• Tea, which contains antioxidants that some research suggests may help prevent fatty deposits building up and improve blood flow.
• Foods containing vitamin E — such as avocados, dark green vegetables, vegetable oils and wholegrain products. Eat these foods rather than relying on supplements, which have not been shown to have the same protective effects.
• Garlic. A compound in fresh garlic (allicin) has been found to lower total and LDL cholesterol.
• Foods enriched with plant sterols/stanols. A daily intake of about 2 to 3 g can lower LDL cholesterol by roughly 10%, equivalent to 2 to 3 serves of enriched foods such as some spreads, yoghurts, milk and breakfast cereals.

How to reduce your risk with healthy eating#

• Limit fried fast food and processed foods.
• Replace energy from saturated fats (such as butter, coconut oil and cream) with unsaturated fats from seeds and plants (such as extra virgin olive oil, avocado, sunflower, canola, safflower, peanut, soybean and sesame), and foods such as nuts, seeds, olives and soy.
• Increase the amount and variety of plant foods — more vegetables, fruits and wholegrain cereals.
• Reduce refined carbohydrates with a high glycaemic index, including foods with added sugars.
• Limit unprocessed red meats (such as beef, lamb, pork and game meats); when you do eat red meat, choose lean, unprocessed or minimally processed cuts, trim visible fat and remove skin from poultry. Avoid processed meats such as sausages, ham, salami and prosciutto.
• Eat legumes regularly — such as reduced-salt baked beans, soybeans, lentils and tofu.
• Snack on a handful of raw, unsalted nuts on most days (especially walnuts and almonds).
• Eat oily fish at least once a week.
• Reduce your salt intake and use herbs and spices for flavour.
• If you have elevated cholesterol, switch to low-fat or non-fat dairy and limit eggs as advised.
• Be mindful of portion sizes, which have grown over time. A healthy plate is roughly ¼ protein, ¼ carbohydrates and ½ vegetables.
• If you drink alcohol, keep it within recommended limits — a high alcohol intake raises blood pressure and can increase blood triglycerides.

Key points#

• An unhealthy diet is one of several contributing risk factors for heart disease.
• A blocked artery cuts off the heart’s oxygen supply and damages or kills heart cells.
• Some risk factors cannot be changed, but many — including diet, weight, blood pressure and cholesterol — are within your control.
• Replacing saturated and trans fats with unsaturated fats, eating more plant foods, and cutting salt and processed foods all help protect your heart.

Where to get help#