A daily glass of pure juice could be the most effective way to ensure you get enough vitamin C from your diet, new research suggests.

The latest study, published in the journal Nutrients, found that drinking 100 % fruit and vegetable juice results in the body absorbing higher levels of vitamin C compared with taking a vitamin C supplement or eating the whole fruits and vegetables.

In a randomised clinical trial, university researchers from South Korea compared vitamin C levels in the blood after participants consumed equivalent doses of vitamin C (102 mg) from three sources: a tablet; chopped tomatoes, peppers, and mandarin oranges; and a juice made from these same fruits and vegetables.

The juice was found to deliver the highest vitamin C levels to the bloodstream, a result attributed to the juice matrix enhancing the vitamin C’s availability for absorption.

The “juice matrix” refers to the way the components of fruit juice – such as polyphenols, vitamins and minerals in solution – work together to make vitamin C easier for the body to absorb.

Vitamin C is a crucial water-soluble compound that supports essential physiological processes. While most animals can synthesise vitamin C internally, humans and a few other mammals must obtain it through dietary sources due to a genetic mutation.

Vitamin C is essential for breaking down nutrients like tyrosine, folic acid, and tryptophan. It also helps your body produce collagen, supports your immune system, and acts as a powerful antioxidant.

Lead researcher, Dr Mijoo Choi, said: “The juice matrix appears to facilitate better absorption of vitamin C, making it a practical choice for those looking to optimise their intake.”

Award winning dietitian and public health nutritionist, Dr Frankie Phillips, added: “With winter flu season approaching, it’s especially important to make sure you’re getting enough vitamin C into your body to support your immune system. This new study emphasises how a simple glass of fruit juice is an excellent way to maximise absorption of vitamin C. A daily glass of orange juice provides more than 80 % of the European recommendation and is a nutritious start to the day.”

Contrary to concerns – oft repeated on social media – that the manufacturing process destroys the nutritional value of shop bought 100 % orange juice, researchers from leading universities in Spain and Italy have found levels of polyphenols – valuable bioactive compounds linked to health – are similar in home-squeezed and shop-bought juice.

The study, published in the International Journal of Food Sciences and Nutrition*, compared the most popular shop bought orange juices in the UK, Germany, France and Spain against freshly squeezed ‘Navelina’ oranges. It found that while home squeezed juice contains more vitamin C than shop-bought equivalents, this degrades significantly over time and is expected to reach shop bought juice levels after a week.

The study also established that shop bought orange juice contains 94 % of European recommendations for daily vitamin C intakes – set at 90 mg for men and 80 mg for women – meaning only a minor impact on consumers from a nutritional standpoint.

Vitamin C, found in fruits and vegetables, is essential for human health since it can’t be synthesised by the body and is involved in many biochemical functions including immunity, neutralising free radicals, iron absorption, bone formation and synthesis of collagen. Low intakes can be noticed as poor wound healing and gum inflammation.

Lead scientist in the study, Dr Cristina Viguera from the Department of Food Science and Technology at CEBAS-CSIC, said: “Our research indicates that there’s limited nutritional advantage to spending time home squeezing oranges when you can obtain similar levels of polyphenols and most of the vitamin C you need from a good quality shop bought version.

“We also found that shop bought orange juices preserve their bioactive compounds during storage and the brand, country or manufacturing process made little difference to the polyphenols or vitamin C. Overall, orange juice is still a rich source of vitamin C whether it’s freshly squeezed or purchased”.

*Salar et al. (2024) Comparison of vitamin C and flavanones between freshly squeezed orange juices and commercial 100 % orange juices from four European countries. https://pubmed.ncbi.nlm.nih.gov/38230429/.