English breakfast tea may aid weight loss by boosting metabolism, but only if it is drunk without milk, new research reveals.
A black brew is thought to raise metabolism as its larger molecules are poorly absorbed in the intestine, which may encourage the growth of weight loss-boosting bacteria, a study found.
Research has previously revealed English breakfast tea only relaxes blood vessels, which leads to improved blood flow, when taken without milk.
The new study also found both black and green tea appear to have weight-loss benefits by reducing levels of intestinal bacteria associated with obesity and increasing those linked to lean body mass, the study found.
Study author Dr Zhaoping Li from the University of California, Los Angeles, said: ‘For black tea lovers, there may be a new reason to keep drinking it.’
English breakfast tea could aid weight loss by boosting metabolism, new research reveals
SPECIFIC BACTERIA IN YOUR STOOLS REVEALS WHETHER YOU CAN LOSE WEIGHT
Your stools reveal whether you can lose weight, research suggested last month.
People cannot shed the pounds without a specific bacteria in their faeces, even if they eat a healthy diet, a study found.
Having low levels of the bacteria Prevotella in the trial’s participant’s stools prevented them from losing weight regardless of whether they were consuming fruits and vegetables or heavy, rich food and sweets, the research adds.
Only around 50 per cent of people are thought to have sufficient Prevotella levels in their gut, the study found. Prevotella is associated with plant-based diets – one that is abundant in fruit, vegetables, leafy greens, seeds, nuts, beans and lentils with little or no animal products.
Previous research suggests Prevotella may aid weight loss by influencing fat storage and how people respond to hunger hormones.
Study author Professor Mads Fiil Hjorth from the University of Copenhagen, said: ‘The study shows that only about half of the population will lose weight if they eat more fruit, vegetables, fibres and whole grains. The other half of the population doesn’t seem to gain any benefit in weight from this change of diet.’
How the research was carried out
The researchers gave four groups of mice different diets for four weeks.
These diets included: low-fat, high-sugar; high-fat, high-sugar; high-fat, high-sugar and green tea extract; and high-fat, high-sugar and black tea extract.
At the end of the study, the researchers assessed the mice’s weight, bacteria content in their large intestine and fat deposition in their liver tissues.
‘For black tea lovers, there may be a new reason to keep drinking it’
Results reveal mice receiving either tea extract see their weight drop to the same level as those having a low-fat diet.
Mice receiving any tea extract also have less intestinal bacteria associated with obesity and more microbes linked to lean body mass.
Yet, only black tea-extract consumers possess a bacteria associated with improved metabolism.
This is thought to be due to black tea’s molecules being larger and therefore lingering in the large intestine rather than being absorbed. This may help to enhance the growth of beneficial bacteria involved in metabolism.
Lead author Professor Susanne Henning said: ‘It was known that green tea polyphenols are more effective and offer more health benefits than black tea polyphenols since green tea chemicals are absorbed into the blood and tissue.
‘Our new findings suggest that black tea, through a specific mechanism through the gut microbiome, may also contribute to good health and weight loss in humans.
‘The results suggest that both green and black teas are prebiotics, substances that induce the growth of good microorganisms that contribute to a person’s well-being.
Dr Li added: ‘For black tea lovers, there may be a new reason to keep drinking it.’
The findings were published in the European Journal of Nutrition.