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Study says vitamin C rich foods could lower your Type 2 diabetes risk, so here’s what to eat

Study says vitamin C rich foods could lower your Type 2 diabetes risk, so here’s what to eat
(Image credit: Getty)

As two out of every five Americans are expected to develop Type 2 diabetes in their lifetime, according to CDC data, looking at ways to reduce our risk is important. A recent study published in the British Medical Journal says that eating and drinking foods rich in vitamin C could lower your risk of developing Type 2 diabetes. 

Drinking a 150ml glass of pure fruit or vegetable juice as part of your five-a-day (minimum) could lower your risk of Type 2 diabetes, researchers say

The researchers, led by experts from the University of Cambridge, found that pure juice (made from whole fruits and vegetables, with no additives) is associated with higher blood levels of protective vitamin C and carotenoids (plant pigments that give vegetables and fruits their bright colors).

Vitamin C and a lower Type 2 diabetes risk

The findings are based upon diets and blood samples collected from 9,754 participants who each developed new-onset Type 2 diabetes. They were compared with a group of 13,662 adults who remained diabetes free 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.

(Image credit: Pexels)

The study discovered that having higher blood levels of protective vitamin C and carotenoids, in addition to a higher overall bioactive score, was statistically linked to a lower risk of Type 2 diabetes. 

As such, researchers concluded that eating more fruit and vegetables daily - five portions a day at the minimum - especially if you don’t usually eat these types of foods, could help prevent Type 2 diabetes

The study found that:

  • 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

Which vitamin C rich foods are best?

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

Type 2 diabetes risk lowered by specific fruits and veg: a photo of freshly squeezed orange juice

(Image credit: Getty)

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.

What to eat to lower your Type 2 diabetes risk

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.”

Type 2 diabetes risk lowered by specific fruits and veg: an image showing a plate of food considered low GI and therefore suitable for people with diabetes

(Image credit: Getty)

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."

Type 2 diabetes risk lowered by specific fruits and veg: an image of avocados, a fruiting food that helps lower the risk of developing Type 2 diabetes

(Image credit: Getty)

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.” 

A blender is a great choice for getting more fiber out of your fruits and veggies, though some people also enjoy using a juicer to make their daily juices.

It's ok to buy fruit and vegetable juices too
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. 

Claire is Health and Wellness Editor at Top Ten Reviews and covers all aspects of health, wellbeing and personal care. With over 17 years' experience as a qualified journalist, writer and editor, Claire has worked across some of Future's most prestigious, market-leading brands. Due to past struggles with insomnia, she is particularly passionate about the role quality sleep plays in our physical and mental health, and loves helping readers to sleep better. Claire is always keen to hear from brands regarding products and services that can help readers feel healthy, happy and empowered.