Should you be eating more plants and less meat? The underlying benefits and scientific evidence explained

Should you be eating less meat and more plants? Professor Robert Thomas explains. Photograph by GettyShould you be eating less meat and more plants? Professor Robert Thomas explains. Photograph by Getty
Should you be eating less meat and more plants? Professor Robert Thomas explains. Photograph by Getty | getty
NationalWorld’s expert Professor Robert Thomas explains whether you should be eating more plants and less meat

A thought-provoking study published by Dr. Kamiński last week added to the current flurry of interest in plant-based diets. He analysed the nutritional content of veggie, meat substitute, and meat meals in over 50 fast-food outlets across the world. The data showed that there were more calories and sugar in the veggie meals yet more salt in the meat meals, overall concluding that they were both as unhealthy as each other.

This study did not actually measure the long-term consequences of regularly eating fast foods. It also did not take into account other potentially harmful effects of high meat intake, such as the cancer-forming chemicals, altering the balance of gut bacteria, and increasing the level of inflammation in the body. Notwithstanding the environmental damage of meat production. Above all, it addressed highly processed, deep fried plant products such as faux chicken, often packed with artificial flavours, preservatives and colour, rather than well prepared, fresh, meat free dishes.

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This did not stop headline-grabbing enthusiastic carnivores from hijacking the conclusions to support outrageously high and unnecessary meat intake in western-style countries. Please don't be put off; making a positive step to increase plants and decrease meat consumption to less than three times a week is one of the healthiest commitments you can make to help your current and future well-being.

High-meat, low-plant diets are major contributors to main chronic conditions, including obesity, dementia, osteoporosis, diabetes, high cholesterol, high blood pressure, and human disease. It is a well-established fact that cancer rates are lower among vegetarians. An Oxford University study found that eating meat no more than three times a week could prevent 31,000 deaths from heart disease, 9,000 from cancer, and 5,000 from stroke each year.

The scientific data shows that it is  not just the quantity of meat that matters, but also the quality ,how it is preserved and cooked. Processed meats such as many sausages, bacon, sliced ham and all tinned meats are the main perpetrators. The European Prospective Investigation into Cancer (EPIC) study reported a strong link between red meat intake and cancer. Other analyses have linked eating processed meat with a 30% greater chance of premature death from any cause.

Harmful culprits in meat include Heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs), which are toxins created when meat is grilled, fried, or chargrilled over an open flame. Specifically, HCAs are formed when amino acids, sugars, and creatinine (found in the meat’s muscle) react at high temperatures, while PAHs are formed when fat and juices from the meat drip onto the fire and then rise up in the smoke that is generated, sticking to the surface of the meat. There is no debate from numerous studies that eating fried, well-done, charred, smoked, or barbecued meats is associated with an increased risk of arthritis, dementia, and cancer, particularly arising in the bowel, pancreatic, and prostate.

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Processed meats are also often high in nitrates, other preservatives and even sugar. One of the largest, and well conducted studies in the UK called the UK biobank study found that even eating two meals with processed meats a week was linked to higher rates of breast cancer. Nitrates are actually found in many plants including beetroot, celery, spinach and other leafy green vegetables but in this form they are not harmful. In fact, they are very healthy because they combine with vitamin C and phytochemicals (see below) to convert the nitrates to nitric oxide. Nitric oxide (NO) relaxes muscles around arteries, improving blood flow to organs such as the heart and muscles and reducing blood pressure, improving energy levels, sports performance and mental agility. On the other hand, nitrates in meat combine with the protein in the meat to form harmful substances called nitrosamines which cause excess inflammation, joint pain, fatigue and brain fog as well as damaging our DNA, causing cancerous mutations.

On the bright side, meat eaters who also have a high intake of vegetables, fruit, whole grains and spices only have a moderately increased health risk, as opposed to salad-dodging carnivores. The phytochemical in plants can help diminish nitrosamine formation by converting nitrates to nitric oxide. So, when eating meat try to make sure you include a lot more vegetables and spices at the same time.

Other factors that affect nitrosamine formation is the profile of bacteria in the gut. The "friendly" varieties block the formation of nitrosamines. Conversely, harmful bacteria such as Helicobacter pylori can create an environment conducive to nitrosamine formation, which increases the risk of stomach cancer. Excess meat intake is actually one of the causes of poor gut health along-side smoking, processed sugar, artificial sweeteners, excess alcohol and lack of exercise. Plants, on the other hand, help gut health by acting as prebiotics which feed the growth of healthy bacteria and impede the formation of unhealthy bacteria. Prebiotics such as inulin, lignans and beta-glucans are abundant in chicory, leeks and asparagus, onions, garlic, asparagus, mushrooms, fruit beans and grains and even, in moderation, resveratrol in red wine.

The fibre in many plants similarly promotes healthy gut bacterial growth. Moreover, experimental studies have demonstrated that short-chain fatty acids produced during the fermentation of dietary fibre in the colon help feed the gut lining cells, improving gut integrity preventing a leaky gut which leads to inflammatory toxins entering the body. Not a surprise then that numerous epidemiological studies have established a strong relationship between low dietary fibre intake and the risk of various cancers, particularly bowel cancer.

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Legumes and soy are rich in high-quality vegetable protein, vitamins and fibre but they also have beneficial hormonal effects. A robust study from the USA reported that women with breast cancer who regularly consumed soy products had a 32% lower risk of breast cancer and a 29% decreased risk of death. Another major analysis reported that increased intake of soy resulted in a 26% reduction in prostate cancer risk.

Nuts, in particular, are super healthy. They have unsaturated fatty acids and essential minerals such as zinc, potassium, calcium, magnesium, flavonoids and cholesterol-reducing phytosterols. Well-conducted studies have shown that eating a handful of nuts such as almonds, walnuts, hazelnuts, and brazils more than three times a week reduces the risk of heart disease, diabetes, and cancer by up to 25%.

Plants are rich in natural chemicals called phytochemicals which provide the colour, aroma and taste but also have enormous health benefits. Phytochemicals are abundant in vegetables, salads, herbs, teas, nuts, fruits, mushrooms, seeds and legumes more often used in Mediterranean and Asian diets. Population studies have shown that their higher intake is linked to a lower risk of cancer , diabetes, arthritis, dementia, premature ageing and many other chronic degenerative diseases. Their underlying mechanism of benefit of phytochemicals includes:

  • Reducing excess inflammation in the gut, brain, and the whole body.

  • Encouraging the production of antioxidant enzymes, protecting us from carcinogens.

  • Blocking the formation of toxic chemicals from meat.

  • Acting as prebiotics, which improves gut flora.

  • Slowing the transport of sugar across the gut wall, reducing the risk of diabetes.

  • Reducing joint pains and aiding in the regeneration of cartilage.

  • Encouraging bone formation, thereby reducing the risk of osteoporosis.

  • Helping to restore circadian rhythm, improve sleep, and reduce daytime fatigue.

  • Improving mood, putting us in a better frame of mind to live healthily.

    The typical western diets, on the other hand, are dreadfully deficient in phytochemicals, meaning we need to eat a lot more of them. Ideally we should aim to have one or more vegetable, fruit or other phytochemical rich food with every meal of the day. A recent study showed that boosting their intake with an enhanced recovery from long covid. Ongoing studies are also investigating whether supplementing these foods could enhance muscle strength, libido and their anti-cancer properties. They are particularly important for men and women who are physically active and those wishing to improve their sports performance. They help training, recovery and motivation by:

  • Protecting joints and tendon;

  • Reducing delayed-onset muscle symptoms and muscle damage

  • Improving muscle and tissue oxygenation

  • Elevating mood and motivation to exercise

  • Reducing viral colds and flu, which disrupt training.

    Other convincing evidence for a plant based diet comes from studies of identical twins. For example, a study of 22 pairs of identical twins randomised one pair to a vegetarian diet and the other to a healthy omnivorous diet. The meat-free twin, even by 8 weeks, had lower cholesterol, better fasting insulin (a marker of potential future diabetes) and better body weight. An ongoing Netflix series, although a less formal scientific evaluation, demonstrated similar findings and additionally suggested improved energy levels and feelings of wellbeing. For the general population the evidence for benefits of increasing plant intake is extensive. To mention just a few, an Adventist study found that vegetarians have approximately half the risk of developing diabetes. Vegetarian diets have consistently been shown to have lower systolic and diastolic blood pressure , lower cholesterol levels and hence a lower risk of ischemic heart disease compared to meat eaters.

    Finally, it should be mentioned that there are some benefits to eating some meat, as it is an easily absorbable source of protein, a good source of vitamin B12 and if it is sourced from an animal that has been reared on grass and is free-range, is high in omega 3. Young women with periods, who are at a higher risk of iron deficiency, would benefit from some meat as it would help protect them from anaemia. Vegans may also actually have a higher risk of depression and many people enjoy the taste of meat and feel their lives are less fulfilled without it. In terms of nutrition, however, it is possible to get all these nutrients from a plant based diet albeit requiring careful planning, discipline and certainly not relying on veggie options in fast food outlets.

    If you are considering cutting out or reducing meat in your diet, it may be worth considering the following tips to help you keep meat intake at a safe level:

  • Go for quality, not quantity, and try to limit meat consumption to 2-3 times a week.

  • Use meat for its taste, but not as the main content of the meal.

  • Meat shouldn’t be your main protein; include fish, quinoa, and pulses like lentils.

  • Eat plenty of herbs, spices, and vegetables with every meal.

  • Eat a handful of nuts at least 3-4 times a week.

  • Avoid processed sausages, hot dogs, bacon, pies, tinned, and smoked meats.

  • Try to go for free-range, organic, or at least grass-fed animals.

  • Avoid barbecued or blackened meats and reduce the heat when grilling.

  • Remove charred portions of meat.

  • Avoid direct exposure of meat to flame or a hot metal surface.

  • Consider making a casserole rather than frying or burning meat on the barbecue.

  • Put more beans and vegetables and less mince in chilli or Bolognese sauces

    For adequate calcium intake, include tofu, mustard, choy, and kale.

  • For adequate omega-3 intake, include ground flax seeds, Chia seed, walnuts, and avocado.

  • For adequate vitamin B12, consider laver bread (Wales) or dried nori seaweed (Japan). In conclusion, you will see major benefits if you decide to start a plant-based diet, including the possibility of reducing the number of medications you take to treat a variety of chronic conditions, lower body weight, decreased risk of cancer, and a reduction in the risk of death from ischemic heart disease.

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