Eating at least five portions of colorful fruits and vegetables a day, which includes drinking a 150ml glass of 100% pure fruit or vegetable juice, could lower your risk of developing Type 2 diabetes, according to a new study published today in the British Medical Journal. Researchers, led by a team at the University of Cambridge, found that pure juice is associated with higher blood levels of protective vitamin C and carotenoids (plant pigments which give some fruit and veg their bright colors).
The findings are based on the diets and blood samples of 9,754 participants who developed new-onset Type 2 diabetes, compared with a group of 13,662 adults who remained free of diabetes during follow-up consultations from over 340,000 people taking part in the European Prospective Investigation into Cancer and Nutrition.
After adjusting for lifestyle, social and dietary risk factors for diabetes, blood levels of vitamin C and carotenoids (bioactive compounds found in orange, yellow and red fruits and vegetables) were assessed and an overall ‘bioactive score’ was calculated. The study found that:
having higher blood levels of vitamin C and carotenoids, as well as a higher overall bioactive score, was statistically linked to a lower risk of type 2 diabetes. This led the researchers to conclude that boosting fruit and vegetable intakes, especially amongst habitual low consumers of these foods, could help to prevent type 2 diabetes.
- Higher blood levels of vitamin C and carotenoids, as well as a higher overall bioactive score, is statistically linked to a lower risk of Type 2 diabetes
- Boosting fruit and veg intake, especially amongst people who don't normally consume these foods, could help prevent Type 2 diabetes
- Participants with the highest intakes of fruit and veg had up to a 50% reduced risk of diabetes compared to those with the lowest intakes
- 100% pure fruit and vegetable juices have the highest bioactive score - a higher overall bioactive score is linked to lower risk of developing Type 2 diabetes
As we know, fruit juices, especially citrus juices, contain 80-100% of the daily recommendation in one glass. From the study, researchers discovered that the top-scoring categories for vitamin C were pure fruit and vegetable juices, followed by citrus fruits, fruiting vegetables (such as tomatoes, and cabbage).
In terms of an overall bioactive score, the following foods were rated top:
- Root vegetables
- Fruit and vegetable juices
- Tomatoes, avocados, peppers, courgettes and other fruiting foods
- Citrus fruits
Cases of Type 2 diabetes, a condition that causes the level of sugar (glucose) in the blood to become too high, and where patients monitor blood sugar levels using glucose meters, has risen dramatically over the past decade alone. The CDC states that 90-95% of the 34 million Americans with diabetes have Type 2 diabetes, so prevention of further Type 2 cases is a major public health concern.
Commenting on the study, dietitian Dr Carrie Ruxton, PhD, said: “While it’s important to eat at least five portions of fruit and vegetables daily, this study suggests that certain categories are more effective than others for raising blood levels of specific compounds.
“Pure fruit and vegetable juices were most strongly correlated with vitamin C levels, while root vegetables were top for the overall bioactive score.”
A second study published in the same journal also shows that wholegrain foods are also associated with a lower risk of developing Type 2 diabetes.
Foods that lower your risk and boost your health
Inevitably you may have questions about the new study, so we asked Dr Ruxton to shine a spotlight on certain areas of the study’s findings. In particular, why are 100% pure fruit or vegetable juices more protective than lesser quality juices?
“Pure juices contain similar vitamin, mineral and bioactive (carotenoid, polyphenol) properties to the fruits or vegetables used to make the juice,” explains Dr Ruxton. “Therefore, they are more protective than ‘juice drinks’ which are diluted with water and which may contain added sugars.
“When compared against whole fruits and vegetables, juices have a lower fibre content - by around 1g per serving - and should be seen as complementing the fruits and vegetables in our diets rather than replacing them. This is why the official advice recommends that a 150ml serving of juice or smoothie counts as a portion of fruit, but we shouldn’t replace all our fruit and vegetables with juices.”
If you’ve been put off drinking these types of juices in the past because of the sugar content, Dr Ruxton explains that there is a difference between natural sugars and added sugars. “The natural sugars in juices still count towards our daily sugar maximum limit, but research shows they behave differently in the body to added sugars. This is because, in juice or fruit, the sugars exist in a natural matrix with other nutrients and bioactives.
“The rich polyphenol content probably explains why pure fruit juices are classed as low glycemic index (GI) drinks, as opposed to sugary fizzy drinks which are classed as medium-high GI,” Dr Ruxton continues. “Other studies have found no links between fruit juices and diabetes, or with obesity, while the opposite has been found for sugar-sweetened beverages.”
Other lifestyle changes if you're prediabetes
For people considered prediabetes, there are other diet and lifestyle changes that could lower your risk of developing this condition. “The greatest predictor of Type 2 diabetes risk is excess weight,” says Dr Ruxton, “so keeping weight within a healthy range by limiting calorie-rich foods (cakes, biscuits, sugar-sweetened drinks, alcohol) and taking more exercise (resistance exercise is the best) are effective ways to prevent Type 2 diabetes.”
Simple bathroom scales can help you monitor your weight, while wearing one of the best fitness trackers prompts you to move more through daily and weekly activity targets. These could involve cardio exercises with a treadmill or exercise bike, for example, or resistance training as advised by Dr Ruxton.
“In pre-diabetes, people can often have underlying chronic inflammation, which can be helped by regularly eating berries, citrus fruits, green leafy vegetables, oily fish, olive oil instead of butter/vegetable oil, and nuts and seeds."
How many portions of fruit and veg should you eat?
To increase your blood levels of vitamin C and carotenoids, Dr Ruxton advises eating the following portions of fruit and vegetables each day: “The minimum should be five a day including a 150ml glass of fruit or vegetable juice. This is easier than you think as frozen, tinned and dried all count.
For a simple daily plan, Dr Ruxton advises:
- A glass of orange juice with breakfast
- An apple or orange for a snack
- Two servings of veg with dinner
- A handful of berries or raisins with natural yogurt for dessert
“I have a Nutribullet, so I enjoy adding fresh spinach leaves to frozen berries and a shot of orange juice to make a nutritious breakfast smoothie. For vegetable juices, my favorite is carrot with apple and fresh ginger.”
And if you’re wondering whether it’s better to make your own juices rather than buy them from a health food store, Dr Ruxton has some great insight here too: “Any 100% juices are similarly good, whether they are fresh or commercially-squeezed. Home-made juices have more vitamin C but need to be made fresh each time as the vitamin C degrades when exposed to oxygen.
“Commercially-squeezed juices are richer in polyphenols as the juicing process is more thorough than home squeezing. They are also high in vitamin C as they are generally bottled with minimal exposure to oxygen.”
If you suspect you may be prediabetes, or are showing Type 2 diabetes symptoms, contact your doctor or healthcare professional and schedule an appointment for a medical check-up. Lowering your risk of developing Type 2 diabetes is possible with the right diet and lifestyle changes, including lowering excess weight and eating a rainbow diet, but expert guidance and treatment should be your first port of call.