A plant-based diet is one that focusses on the consumption of fruits, vegetables, whole grains, beans, nuts and seeds, whilst minimising or avoiding animal-derived and processed foods. There isn’t a precise definition of this term, which includes vegan (100% plant-based), vegetarian and flexitarian diets. Most people consider a plant-based diet one where at least 85% of calories are derived from plant foods. There are numerous benefits to eating in this way and it is healthy and safe to do so at all stages of life (1).
So, what are some of the expected benefits?
A healthy diet is the main way to maintain a healthy weight. A plant-based diet predominantly focusses on low-calorie foods, which are packed full of essential nutrients. One of most important nutrients for maintaining a healthy weight is fibre and this is only found in plant foods. Fibre not only keeps you feeling full for longer, but it also promotes a healthy gut microbiome, which in turn impacts body weight. On a plant-based diet, you can usually eat to fullness without worrying about portion control or calorie counting. This is certainly true when you concentrate on eating minimally processed plant foods, as close to nature as possible (2–4).
High blood pressure is a leading cause of illness, yet for most people it is possible to maintain a normal blood pressure throughout life by adopting healthy lifestyle habits. These include regular physical activity, avoiding tobacco smoking and alcohol consumption, sleeping well and managing stress. When it comes to diet, plant-based diets are best for maintaining a healthy blood pressure and have a similar effect to medications in people with high blood pressure (5,6). There are certain foods that stand out in their ability to reduce blood pressure. These include whole grains, nitrate-rich vegetables, such as leafy greens and beetroot, flaxseeds and even beetroot juice and hibiscus tea. Remember, minimising salt consumption is also essential for maintaining a healthy blood pressure.
People who avoid all animal foods have the lowest cholesterol levels of all diet patterns (7). This is because a plant-based diet avoids or minimises ‘nutrients’ that increase blood cholesterol, namely saturated fat and dietary cholesterol, and also include nutrients that naturally keep blood cholesterol low, such as fibre, unsaturated fatty acids, plant sterols and stanols. Some standout foods for lowering cholesterol that are part of the Portfolio eating plan are soya, nuts and foods high in soluble fibre found in fruits, vegetables, beans and whole grains such as oats (8).
Type 2 diabetes is driven by insulin resistance, a condition caused by the abnormal accumulation of fat inside the muscle, liver and pancreatic cells. This fat accumulation inhibits the action of insulin and thus leads to elevated blood glucose. Lowering blood glucose levels by using medications or avoiding carbohydrate-rich foods just treats the symptoms without addressing the root cause. Foods associated with a high risk of developing insulin resistance and type 2 diabetes are meat, eggs, excess free sugar and processed foods in general (9). This is because these foods lead to inflammation, generate advanced glycation end products and expose you to higher levels of saturated fat, haem iron and nitrites and nitrates (from processed meat), all of which drive insulin resistance. Fruits, vegetables, beans and whole grains are all associated with a significantly lower risk of type 2 diabetes and once again fibre is a key nutrient along with antioxidant and anti-inflammatory compounds. In general, avoiding the consumption of animal foods can reduce your risk of type 2 diabetes by up to 50% (10).
The main risk factors for heart disease are being an unhealthy weight, high blood pressure and cholesterol and type 2 diabetes. By avoiding these conditions, you significantly reduce the risk of heart disease. (11). The main foods that increase the risk of heart disease are those high in saturated fat, essentially all animal-derived foods, and those high in free sugar, mainly processed foods and sugar-sweetened beverages. Don’t forget that palm oil and coconut oil, despite being plant-based, are also high in saturated fat and are thus best avoided or at least kept to a minimum. In addition, sugary treats, even if they are plant-based, are not going to be healthy. The good news is that the type of saturated fat in chocolate is not harmful and so dark chocolate can be enjoyed as part of a healthy plant-based diet. Plant-based diets are full of all the foods that are known to support heart health and overall reduce the risk of heart disease by around 25-30%. A daily portion of nuts is also great for heart health.
The causes of cancer are varied and complex. Eating a plant-based diet is just one of several healthy habits that is associated with a lower risk of cancer, especially breast, colon and prostate cancers. This is because you avoid cancer causing substances found in red and processed meat and emphasise foods that contain cancer suppressing substances, including antioxidants and anti-inflammatory compounds, found in plant-based foods. Once again, fibre and fibre-rich foods are key to lowering the risk of cancer. Being overweight poses a significant risk for developing cancer as fat cells produce chemicals, hormones and growth factors that drive the growth of cancer cells. Overall, consuming a plant-based diet can reduce your risk of cancer by about 15% (12,13). A plant-based diet is also best for improving health, well-being and survival after a cancer diagnosis.
Mental health and well-being is a complex topic with many physical, social and psychological factors playing a role. However, there is no doubt that a healthy diet can improve our mood. One major way in which food influences mood is by affecting the health of our gut microbiome. The gut bacteria are responsible for making a range of brain active hormones and also produce chemicals that communicate directly with the brain. You guessed it, fibre-rich foods are key to providing nourishment for our gut microbiome, which is why fruits and vegetables come out top when it comes to improving mental health and well-being (14). In a general sense, mental health disorders are driven by chronic low-grade inflammation, a type of cellular stress. Plant-based diets are known to reduce inflammation and thus can support better brain health (15).
The rising rate of dementia is a real threat to our quality of life and is a major burden for healthcare systems and society as a whole. Around 30-40% of dementia case could be prevented or delayed by addressing modifiable risk factors (16). The same risk factors that cause heart disease are implicated in the cause of dementia, both Alzheimer and vascular dementia. By significantly lowering the risk of heart disease you can also reduce your future risk of dementia. The World Health Organisation recommends a Mediterranean diet for prevention of dementia because this way of eating is full of healthy plant foods.
Without a healthy planet there are no healthy people. The climate and ecological crises are now directly affecting human health globally. One of the main drivers of these crises is our food system. Animal agriculture is a major cause of greenhouse gas emissions, biodiversity loss, land, water and air pollution, land use change and more. The most impactful action we can take as individuals is to remove animal foods from the diet and instead eat a plant-based diet. Without exception, the production of all plant foods has significantly less impact on the environment than animal foods. There is now international consensus that if we want to limit global warming to less than 1.5∞C, we need a global transition to a plant-based foods system (17).
The positive impacts of a plant-based diet far outweigh any perceived downsides. In addition to supporting good health, a plant-based diet is full of abundance and flavour and is a joy to adopt. Critics always rush to remark about the lack of B12 in a plant-based diet and the need to supplement. In addition, there is a greater need for vitamin D supplementation than for people following an omnivorous diet. However, given the numerous benefits to human and planetary health, these are small adjustments to make.
Dr Laura Freeman is a GP and Lifestyle Medicine Physician. She is Co-Founder of Plant Based Health Online, an online lifestyle medicine healthcare service that supports patients to adopt healthy lifestyle habits for prevention and treatment of chronic illness. You can book an appointment with Dr Freeman by visiting https://plantbasedhealthonline.com/book
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