Heart disease, stroke and diet

High cholesterol levels in the blood are a major contributor to atherosclerosis but it is also an inflammatory disease.

The formation of atherosclerotic plaques starts with small cholesterol particles sticking to the inner lining of an artery, infiltrating its surface and accumulating there. These cholesterol particles eventually oxidise, which changes their structure and white blood cells gather in the area to clean things up.

However, once white blood cells arrive and start working, they signal for other types of white blood cells to gather and in the meantime, they also release adhesive substances that hold everything in place – a lesion is formed. This part of the process is the inflammatory response that keeps white blood cells active in the area.

Some white blood cells take in the oxidised cholesterol and remove it but if blood levels of cholesterol are high, the lesion will grow further. Other white blood cells take the oxidised cholesterol in but become embedded in the lesion – these are called foam cells and form so-called fatty streaks. As the lesion grows and becomes a plaque, some of these white blood cells die and their contents remain embedded in it, making matters worse and increasing local inflammation. Additionally, calcium from the blood may attach to the plaque and, over time, this can cause hardening of the entire artery.

The other part of the process happens inside the artery wall. As the lining is damaged, some smooth muscle cells from the artery wall migrate into the lining along with collagen fibres and white blood cells and form a bulge that reduces the artery diameter. This is also called fibrous cap/plaque and is prone to rupture over time – when it happens, a small blood clot forms around the area. The clot may tear away along with a part of the plaque and completely block an artery, causing a heart attack, stroke or thrombosis (explained below).

Atherosclerosis takes many years to develop, it is a slow process but once symptoms become noticeable, it’s usually quite advanced.

If the blood supply to the heart is blocked, it causes a heart attack – the heart suddenly fails.

A heart attack can be fatal but it doesn’t have to be. It’s usually caused by a blockage in one of the coronary arteries – arteries that supply blood to the heart muscle. The coronary arteries wrap around the outside of the heart and supply oxygen and nutrients to it while taking away waste products. When these arteries get narrower as a result of plaques, it may cause angina – chest pain, tightness and uncomfortable pressure. If one of these arteries becomes blocked, the heart muscle cannot carry on working and stops, resulting in a heart attack.

If the heart stops for long enough, a heart attack will be fatal but with fast help, the person may survive. They may then have to have an emergency operation where stents (tiny wire-mesh tubes) are placed in the coronary artery to keep it open and to prevent future blockages. Another option is a coronary artery bypass, where blood vessels are re-routed around the affected area to keep it supplied with blood. However, while these procedures keep the person alive, they don’t address the cause of heart disease or atherosclerosis and more problems will likely follow.

In the UK there are around 100,000 hospital admissions each year due to heart attacks – one every five minutes.

Heart failure, despite its name, doesn’t mean the heart stops working – it means that the heart is unable to pump blood around the body properly. It has become too weak or stiff, usually as a result of heart muscle damage – for example, after a heart attack. The heart simply doesn’t work as well as it should and tends to get gradually worse over time.

Developing this condition is a slippery slope because people with heart failure are two to three times as likely to have a stroke as healthy people. It’s estimated that over one million people in the UK are living with heart failure.

Stroke is a sudden and life-threatening event in which an artery supplying the brain is blocked (ischaemic stroke) or a blood vessel in the brain bursts (haemorrhagic stroke). Ischaemic stroke is much more common than haemorrhagic. Both result in a part of the brain suddenly losing some or all of its blood supply which leads to a rapid loss of brain function and requires immediate medical care.

Stroke symptoms may include losing the ability to move and feel, usually on one side of the body, loss of speech, vision, inability to understand or react and dizziness. How much damage a stroke causes depends on how long brain cells remain without blood supply, the size of the affected area and the extent of the blood vessel blockage or damage. Some people recover fully, some partially, whilst for others a stroke can be fatal. There are also mini-strokes, where the damage isn’t so extensive and they may cause only mild symptoms. However, they are dangerous too because if the person doesn’t seek medical attention, their health may further deteriorate.

In the UK, there are around 100,000 strokes each year and data suggests that the average age for someone having a stroke is decreasing, with over a third of strokes in adults aged between 40 and 69. Strokes cause around 34,000 deaths in the UK each year and are the biggest cause of severe disability.

If a blood clot blocks the blood supply to a body part or organ, it’s called thrombosis and symptoms may include pain and swelling in one leg, chest pain or numbness on one side of the body. Complications of thrombosis can be life-threatening, such as a stroke or heart attack.

Thrombosis is a type of embolism, which is a general term for something blocking the blood supply – it can be a blood clot, a fat particle, a bubble of air or another gas or foreign material. Embolisms can be fatal as they can cause heart attack, stroke or lung collapse (pulmonary embolism).

Fats are divided into separate categories based on the structure of the fatty acids they contain. The chemical bonds within fatty acids are described as saturated or unsaturated and this also determines their activity in the body.

• Saturated fats – these are something we don’t need in the diet as our bodies can make them. The main sources of saturated fat are animal products (meat, fish, shellfish, eggs, dairy products, butter, lard, pies, pastries, processed foods and high-fat spreads), coconut oil and palm oil. It’s well-established that a diet high in saturated fat increases blood cholesterol levels – in particular, the dangerous LDL type. The American Heart Association state that replacing saturated fats in the diet with polyunsaturated can reduce the risk of heart disease and related events by about 30 per cent, which is a reduction similar to that achieved by cholesterol-lowering drugs, statins. Read the research.
• Monounsaturated fats – these are not essential in the diet but not harmful as a part of a balanced diet. Monounsaturated fats are found in many plants and vegetable oils. Probably the most common one is oleic acid – an omega-9 fat – the main component of olive, macadamia, avocado and sunflower oils.
• Polyunsaturated fats – these are the essential omega-6 and omega-3 fats – we need them for good health. The main omega-6 fat is linoleic acid found in seeds, nuts, corn, pulses and soya oil. It can be converted into other important omega-6 fatty acids in the body. We usually have enough of omega-6 fats and need to increase the intake of omega-3s.

Omega-3 fats from plants come in the form of ALA (alpha-linolenic acid) which our bodies convert to EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). Rich sources of ALA are ground flaxseeds, hempseeds, chia seeds, walnuts and rapeseed oil. Microalgae contain ready-made EPA and DHA – this is where fish obtain their omega-3s. Algae-derived omega-3 supplements are a much healthier choice than fish or fish oil supplements because they are not contaminated with dangerous pollutants and are sustainable.

• Trans/hydrogenated fats – these fats have a different structure to all other fats and are dangerous to heart health because they raise blood cholesterol levels. Smaller amounts of trans-fats are naturally found in dairy products, lamb and beef fat. Larger amounts can be found in processed foods. These fats are made by the hydrogenation process, which converts liquid vegetable oils into solid fats. The final product is called hydrogenated vegetable oil/fat. Foods that contain hydrogenated fats should be avoided. Read the research.

Note on margarine: margarine used to contain hydrogenated fats and that’s why it gained a bad reputation. However, most manufacturers have since changed their ingredients and production methods, so margarine is a healthy butter alternative (always check the ingredients to be certain).

This rule naturally follows on from all the official recommendations for a heart-healthy diet. A fully vegan diet is the best for your heart and blood vessels. Plant-based foods provide:

• Complex carbohydrates, including fibre – these supply healthy energy for your body and feed your beneficial gut bacteria
• Plant protein – the kind that’s been shown to be so good for the heart by many studies. Best sources are pulses, soya products, wholegrains, nuts and seeds
• Healthy fats – mostly mono- and polyunsaturated essential fats from nuts, seeds and vegetable oils
• Antioxidants, vitamins and minerals – important for good health, anti-inflammatory, keeping blood vessels in good shape and helping to regulate blood pressure
• Phytosterols – these are the natural compounds that block the absorption of cholesterol in the gut

In practice, this means building your diet from wholegrain foods (wholemeal bread, oats, wholewheat pasta, brown rice, quinoa, rye crackers), pulses (beans, lentils, soya, chickpeas, peas and products made from them), fruit and vegetables, nuts and seeds. Older studies focused on low-fat diets but newer evidence shows that choosing the right kind of fat is more important than reducing all fat. Avoid adding lots of oil to foods but there’s no need to avoid nut butters or the occasional avocado.

Green leafy vegetables, such as kale, cabbage, rocket, broccoli, watercress or Brussels sprouts, reduce arterial stiffness and blood pressure, and have an anti-inflammatory effect. They should be on your daily menu.

See sample meal plans here.

These are all the foods that are also plant-based but not healthy and can even raise your risk of heart disease. That’s why you should keep their consumption to a minimum or cut them out completely. This means avoiding foods such as white bread, cakes, pastries, pies, sugary or salty processed snacks, anything deep-fried, sugar-sweetened drinks and alcoholic drinks. Processed foods that contain hydrogenated or partially hydrogenated fats should be avoided altogether.

It’s important to get your daily dose of the essential omega-3 fats because not only they are needed for healthy cells and tissues, they also support healthy gut bacteria and tone down inflammation in your blood vessels.

A daily dose of ALA (1.1 grams for women and 1.6 grams for men) can be obtained from one of these:

• A heaped tablespoon of ground flaxseeds OR a two teaspoons of flaxseed oil
• A heaped tablespoon of chia seeds – it’s best to let them soak a little or blend them in a smoothie to make their nutrients more available
• Two tablespoons of shelled hempseeds
• Ten walnut halves
• Two tablespoons of rapeseed oil (used for cooking or baking)

OR you can take an algae-derived vegan supplement providing 250-500 milligrams of EPA and DHA combined.

We need a regular supply of vitamins B12 and D for our bodies to work as they should. These two vitamins are vital for a healthy cardiovascular system, blood formation, nerve function, regulation of body functions, immune system and bone health. They are essential for everyone and because they are hard to obtain from the diet, many people have low levels or are deficient regardless of what type of diet they eat.

For vitamin B12, take a daily dose providing 50 micrograms or a weekly dose providing 2,000 micrograms. Vitamin B12 is produced naturally by bacteria that live in the soil and traditionally, people and animals would have got it from eating unwashed plants. Food production is now so sanitised that there’s not a trace of B12 left and we need a supplement. Cyanocobalamin is the stable ‘inactive’ form of B12 used in supplements and to fortify foods and it becomes activated once it passes through the stomach – it’s cheap and suitable for most people. Methylcobalamin is the ‘active’ form and costs more but may be a better option for smokers or people with kidney problems as their B12 metabolism is somewhat compromised. Both forms are suitable for vegans.

Lack of vitamin B12 can lead to too much homocysteine in the blood. Homocysteine is a metabolic product of the amino acid methionine and it is further processed with the help of vitamins B6, B12 and folate. High levels of homocysteine in the blood can damage the lining of the arteries and may also make the blood clot more easily, which can increase the risk of blood vessel blockages and contribute to cholesterol plaque build-up, increasing the risk of heart disease and stroke.

For vitamin D, take a daily dose providing 10 micrograms (400 international units) from October to April if you live in the Northern Hemisphere or all year round if you always cover up, protect your skin with sunscreen, have very dark skin or don’t spend any time outside in sunny weather. Vitamin D is made in the skin when it’s exposed to sunlight, in particular the UVB radiation. In spring and summer, most people in the UK can make enough through daily exposure to sunlight for five to 25 minutes. This short time minimises the risks of sunburn and skin cancer. The lighter your skin, the less exposure time you require – ‘little and often’ is the best approach for most people.

In the colder months, there simply isn’t enough of the UVB radiation in sunlight, there’s less sunshine in general and the days are shorter. Even if you work outside, you may still need a supplement in autumn and winter. There are two types of vitamin D and both are suitable to cover your needs – vitamin D2 is always vegan whereas D3 is usually of animal origin but can also be obtained from algae or mushrooms. If it’s the latter, it’s usually declared on the packaging.

Physical activity is a simple, yet very effective heart-protector. It can be in the form of a daily 30-minute walk, a moderate workout twice or three times a week, any outdoor activity that increases your heart rate, or indoor exercise, yoga or even housework if you do it vigorously!

If it’s a low-level activity, a daily routine is recommended, while for moderate and higher intensity activity, twice or three times a week is sufficient.

Stress can be bad news for your heart and circulation. It can cause all sorts of symptoms that are certainly not good for you, such as high blood pressure, insomnia, altered metabolism and digestive issues. We cannot avoid stress, but we can use smart tools to help us deal with it, for example breathing exercises, mindfulness techniques, meditation, yoga, tai chi, arts, music or even gardening. Spending quality time socialising and/or relaxing is also important.

Even if your diet is perfect, you don’t smoke or drink alcohol, keep your salt intake low and engage in physical activity, you can still be at high risk of cardiovascular events if your stress levels are high and unregulated.

As clinical trials show, heart disease can be halted and in many cases even reversed with the right kind of diet and lifestyle changes.

Since 1980s, there have been many trials of wholesome plant-based diets and their effect on heart disease.  Most people have had excellent results – significant drops in cholesterol, blood pressure and reduced plaques in their arteries. Atherosclerosis develops slowly over many years so while people had great results after a year, their results were even better after several years.

As one recent review summarised – vegan or almost-vegan diets have been the only ones to show success in reversing heart disease and reducing atherosclerotic plaques.

A wholesome vegan diet can produce truly life-changing results but it’s also important to engage in some moderate physical activity and practice stress-management.

Read the research.

Omega-3 fats are essential for us – we need them for good health because they are a natural component of many of our tissues. We obtain omega-3 fats from plants in the form of alpha-linolenic acid (ALA) and from fish and microalgae in the form of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).

The human body converts ALA into EPA and DHA but this conversion is not very efficient. That’s why many people opt to take EPA and DHA directly in the form of supplements made from microalgae or fish oil. Of the two, supplements made from microalgae are far superior to fish oil because they are more sustainable and don’t contain dangerous environmental pollutants that are often found in fish oil.

Cochrane reviews are considered to be the gold standard quality in science. The most comprehensive Cochrane review of evidence on the subject found that increasing EPA and DHA has little or no effect on cardiovascular events (eg heart attack) or death. They also found that omega-3 supplements do not reduce the risk of heart disease, stroke or death caused by cardiovascular events and that there was little evidence of effects of eating fish. However, eating ALA (from flaxseeds or flaxseed oil, chia seeds, hemp seeds, walnuts or rapeseed oil) may help slightly reduce cardiovascular events, heart irregularities and death. They concluded that increasing plant‐based ALA may be mildly protective for some heart and circulatory diseases.

When it comes to fish oil supplements, another scientific review found a concerning effect – they may actually increase the risk of atrial fibrillation (irregular heartbeat) by 25 per cent and if you take more than one gram daily, the risk may increase by 49 per cent. On the other hand, ALA from plants reduces the risk.

Fish oil is often promoted as heart-healthy but don’t be fooled – it won’t protect you from heart disease.

Read the research.

Red, white and processed meats are all a significant source of saturated fats, cholesterol and haem-iron, they trigger TMAO production and contain no fibre – that’s why they can greatly increase the risk of heart disease. Read the research.

Red and processed meat in particular increase the risk of heart disease, stroke and heart failure. According to a number of studies, replacing them with plant-based foods slashes the risk.

Meat iron and heart disease

There are two types of iron in the foods we eat – haem iron in meat, poultry and seafood and non-haem iron in plants. The human body uses these forms differently – the absorption of haem iron from meat is unlimited, so we absorb it no matter what. That means high meat consumption can lead to iron overload. The main sources of haem iron are red meat, processed meat, chicken and seafood. On the other hand, the body only absorbs as much non-haem iron as it needs, so we cannot overload on plant iron.

Too much haem iron stimulates the formation of free radicals – dangerous molecules that can damage our DNA, blood vessel walls and increase the oxidation and therefore stickiness of cholesterol particles, making them more likely to form cholesterol plaques leading to atherosclerosis and heart disease. Read the research.

In short, yes. Sensational headlines saying the opposite are not based on sound science and the fact remains that major health organisations and heart experts warn against saturated fats.

It’s because a diet high in saturated fats increases blood cholesterol levels – in particular, the dangerous LDL type. Dozens of studies show similar results – higher saturated fat intakes increase cholesterol levels and when they are replaced by unsaturated fats, cholesterol levels drop. This dietary change can reduce the risk of heart disease and related events by about 30 per cent, which is a reduction similar to that achieved by cholesterol-lowering drugs, statins.

Saturated fats are mainly found in meat, dairy and egg products, butter, lard, coconut and palm oil.

Read the research.

Eggs are a rich source of dietary cholesterol, which may raise blood cholesterol levels, and also choline, from which TMAO (see section Gut bacteria and heart health for details) is produced – both may raise the risk of heart disease as discussed above.

Scientific studies show that people who eat eggs daily have higher risk of heart disease, heart failure and high blood pressure compared to people who rarely eat them. At the same time, other studies didn’t find such clear-cut results. While more research will bring more clarity, it’s obvious that eggs are not heart protectors and may increase the risk of heart disease.

Read the research.

Short-term stress, such as being nervous about a meeting or getting scared by a dangerous situation, is normal and harmless for a healthy person because once the situation passes, the stress is gone. However, for people who already have heart or circulatory issues, even short-term stress can be dangerous. It’s because stress causes blood vessels to constrict and that increases blood pressure – if an artery is already narrowed by plaques, a further constriction might block it and lead to sudden events, such as a heart attack.

Long-term or chronic stress (lasting months or years), on the other hand, can play a major role in the development of heart disease and cause sudden events even in a healthy person and makes matters worse for heart disease patients. Chronic stress can be caused, for example, by a difficult living or financial situation, bereavement, lasting physical or mental health problems, a stressful job or family issues.

In response to stress, which is perceived as danger by the body, the sympathetic nervous system is activated and the hormones cortisol and adrenaline are released. These actions cause an increase in blood pressure, blood lipids (including cholesterol) and blood sugar because they are preparing the body for a ‘fight or flight’ reaction and so it’s important that muscles are well-supplied with oxygen and energy. At the same time, the immune system is blunted while pro-inflammatory substances are released and blood-clotting increases. When there’s no fight or flight and the stressful situation continues, it may lead to a lasting increase in blood pressure, blood sugar, cholesterol levels and triglycerides, and cause or contribute to inflammation in blood vessels which promotes the build-up of atherosclerotic plaques. At the same time, the increased blood clotting poses a risk especially in people who already have atherosclerosis – a blood clot can block an artery. Read the research.

Chronic stress can also be dangerous in another way – often, it triggers unhealthy behaviours, such as excessive drinking, comfort eating, smoking, physical inactivity and disturbed sleep patterns. These are all significant risk factors for heart disease and it’s another reason why stress increases the risk.

As a part of a heart-healthy lifestyle, it’s important to engage in stress management techniques, such as non-competitive physical activity, mindfulness, yoga, meditation, calming breathing exercises, walking – where you connect with nature or whatever it takes for you to release some of the day’s tension!