According to a study published online Jan. 27 in the BMJ and carried out at Harvard TH Chan School of Public Health, Boston, Mass., eat more foods high in flavonoids may help prevent weight gain over time for adults .
They took seven different types of flavonoids, and it turned out that the classes that have been associated with improved weight maintenance were flavonols, anthocyanins, and flavonoids polymers.
Fruits like apples, pears, and berries are the main sources of flavonoids, but can also be found in some vegetables such as red peppers.
The study is the first to observe the relationship between the intake of various subclasses of flavonoids and weight gain. It included data on more than 124,000 men and women in the US who were followed for up to 24 years.
Previous studies have suggested that flavonoids may play a role in weight loss. Most have focused on sub-class of flavonoids found in green tea, but the studies were few.
The new study drew on data from 124.086 men and women who have participated in three prospective studies: the Nurses ‘Health Study (NHS), the Nurses’ Health Study II (NHSII), and the Health Professionals Follow-up Study (HPFS).
Participants were aged between 27 and 65 years old and came from all 50 states of the United States; he has described their weight, lifestyle habits, and recent medical diagnoses every two years between 1986 and 2011. They also documented their diet every 4 years using validated semiquantitative food frequency questionnaires (FFQs).
The researchers looked at seven flavonoid subclasses: flavanones, anthocyanins, flavanols, proanthocyanidins, flavonoid polymers, flavonols and flavones.
The results – adjusted for lifestyle factors – have suggested that people who ate more food by specific subclasses of flavonoids have experienced less weight gain over time.
These flavonoids have had the greatest effect on weight loss: anthocyanins, polymers of flavonoids and flavonols.
One serving a day of many fruits often offers a lot more flavonoids than one standard deviation, that can put these results in perspective. For example, eat only half a cup of blueberries a day would increase the consumption of anthocyanins by 12 standard deviations.
The anthocyanin-rich foods include dark red fruits such as blackberries, red grapes, raspberries, cherries, blueberries and strawberries, with the last two fruits also high in flavonoid polymers, as are tea, nuts and apples. The tea is also rich in flavonols, along with onions and some types of beans.
In the United States currently, most of the people consume less than 1 cup of fruit, and less than 2 cups of vegetables per day. The authors suggest that this should be increased to 2 cups of fruit and 2.5 cups of vegetables.