The goodness derived from eating plant-based foods every day can't be overstated.
Fruit, vegetables, beans, legumes and whole grains contain a wide variety of vitamins, minerals, antioxidants, phytonutrients and dietary fibre — all of which are essential for optimum health.
"Numerous studies have linked a higher consumption of healthy plant foods with a reduced risk of chronic conditions, from type two diabetes and liver disease to cardiovascular disease, digestive issues, certain eye diseases, and even depression and anxiety," says Cyrus Luk Siu Lun, a dietitian and executive committee member of the Hong Kong Dietitians Association.
Five new studies show plant foods can reduce your risk of diabetes and heart disease, combat frailty, improve your cognitive health, and more.
An avocado a day helps lower cholesterol levels
Avocados are high in calories, with a medium-sized fruit (138g/5oz) containing about 21g of fat.
Those who want to lose weight may avoid it for this reason, but a study published in July in the Journal of the American Heart Association found that eating an avocado a day didn't cause weight gain, and in fact lowered cholesterol levels.
"While the avocados did not affect belly fat or weight gain, the study still provides evidence that avocados can be a beneficial addition to a well-balanced diet," says researcher Penny Kris Etherton, a professor of nutritional sciences at Pennsylvania State University in the US.
A daily avocado was linked to a slight decrease in the unhealthy cholesterol low-density lipoprotein (LDL), which makes it good for your health, she adds.
The study lasted six months and involved over 1,000 overweight and obese participants.
Eat fruit frequently to boost mental well-being
When it comes to healthy snacking, you can't beat fruit.
A study by the College of Health and Life Sciences at Aston University in the UK looked at the relationship between mental health and the consumption of fruit, vegetables, sweet and savoury foods.
Study participants who frequently snacked on nutrient-poor savoury foods like crisps were more likely to experience "everyday mental lapses", such as forgetting where they had left keys or why they had gone into a particular room, and reported lower mental well-being.
A greater number of mental lapses was associated with higher reported symptoms of anxiety, stress and depression, and lower mental well-being scores.
Participants who frequently ate fruit, by comparison, were less likely to report symptoms of depression. Researchers did not find any link between everyday memory lapses and fruit and vegetable intake or consumption of sweet snacks.
According to the study's lead author Nicola-Jayne Tuck, "fruit and vegetables are rich in antioxidants, fibre and essential micronutrients which promote optimal brain function, but these nutrients can be lost during cooking. As we are more likely to eat fruit raw, this could potentially explain its stronger influence on our psychological health."
Results of the study were published in May in the British Journal of Nutrition.
Hong Kong's health department recommends that adults consume at least two servings of fruit a day — but most fall short of this amount, Luk says.
"One serving is a medium-sized orange or apple, for instance, two small-sized plums, kiwis or other small fruit, half a bowl of cut fruit, or half a bowl of grapes, lychees or berries." Fresh juice, he adds, is not a replacement for whole fruit.
Plant protein from beans and legumes reduces frailty risk
Frailty is common in older adults, with symptoms that include muscle loss and weakness, fatigue, slow walking speed and unintentional weight loss. The syndrome is associated with falls, longer stays in hospital, difficulty recovering from illnesses and surgery, and mortality.
A study published in March in the Journal of Cachexia, Sarcopenia, and Muscle found that eating more plant protein was associated with a reduced risk of frailty. A higher intake of animal protein was found to be linked to a higher risk.
The study, which looked at data from more than 85,000 women aged 60 and older, also found that replacing animal protein with plant protein may help to prevent frailty.
The main food sources of plant protein identified in the study were bread, cereals, pasta, nuts, beans and legumes, while the main food sources of animal protein included processed and unprocessed red meat, poultry, fish and seafood, eggs, and dairy products.
Healthy plant foods — including coffee — may lower diabetes risk
In a study published in April in Diabetologia, the journal of the European Association for the Study of Diabetes, researchers found that people who consume more healthy plant foods — such as fruit, vegetables, nuts, legumes, whole grains, and tea or coffee — can significantly minimise their risk of type two diabetes.
The study compared people who enjoyed a diet rich in these plant foods with people who ate a diet of unhealthy plant foods such as refined grains and fruit juices and people who ate animal foods such as meat, fish, dairy and eggs.
It found that participants who went on to develop type two diabetes had a lower intake of healthy plant-based foods. Those with type two diabetes typically had a higher average body mass index (BMI) and were more likely to have high blood pressure and high cholesterol levels. They were also less physically active.
As part of their study, the researchers, from the Harvard TH Chan School of Public Health in the US, analysed blood plasma samples from over 10,000 people. The researchers also asked participants to complete food frequency questionnaires.
When choosing healthy plant foods, Luk recommends focusing on a rainbow of colours. The brighter the colour, the more antioxidants and phytochemicals they contain, which means you enjoy an even greater variety of nutrients.
"Red foods like tomatoes and red capsicum, for example, have lycopene, which benefits heart health and is anti-inflammatory," he says.
"Dark green ones like spinach, bok choy — a type of Chinese cabbage — and broccoli are high in iron, folate and calcium, which helps with red blood cell production, healthy cell function and bone health, respectively; while orange and yellow foods like pumpkin, carrot and sweet potato contain beta-carotene and lutein, which are important for skin and eye health and a healthy immune system."
Watermelon may boost cardiovascular and metabolic health
Watermelon is loaded with important nutrients that are good for our bodies. In a review of research from 2000 to 2020, researchers at the Illinois Institute of Technology in the US concluded that citrulline and arginine are important for cardiovascular and metabolic health.
These amino acids found in watermelon help form nitric oxide, a natural compound the body produces that helps relax our blood vessels and assists with lipid reduction and glucose control.
The sweet fruit also contains antioxidants and minerals such as lycopene, polyphenols, potassium and magnesium, which are key to heart health and digestion.
The findings were published in December 2021 in Current Atherosclerosis Reports.