Fruit juices contain a range of minerals, vitamins and bioactive compounds, such as phytochemicals, that are important for good health. Guidelines for a healthy, balanced diet typically recommend plenty of fruits and vegetables are required to supply our vitamin and mineral needs. However, within this model, moderate consumption of 100% fruit juices can make a significant contribution to potassium and some other micronutrients.
Vitamin and mineral claims
European Union regulation 1924/2006 states that, in order to use a nutrition claim, 100 g of a food or 100 ml of a drink must contain at least 15% or 7.5% respectively of the nutrient reference value (NRV). In accordance with this, 100% juices of orange, grapefruit, lemon, pineapple and tomato can be declared a “source” of vitamin C; orange, pineapple and tomato juices meet the criterion for potassium; while orange juice additionally meets the criterion for folate.
The nutrients in fruit juice come directly from the squeezed fruit. When micronutrient levels of vitamin A, folate, vitamin C, calcium, magnesium and potassium were compared in juices versus the whole fruits from which they were derived, no significant differences were found. In some cases, sodium may be higher in 100% fruit juices while the content of potassium, phosphorus and magnesium may be lower compared with the corresponding fresh fruit extract.
Intestinal absorption of non-haem iron is inhibited by some compounds present in foods, such as phytates or polyphenolic compounds, and conversely, is promoted by others, such as vitamin C (ascorbic acid). The role of vitamin C in this regard is so important that the WHO considered its impact on the bioavailability of iron when developing Dietary Reference Values. Thus, consuming 100% fruit juice along with foods rich in non-haem iron can help increase absorption of this mineral.
Pro-vitamin carotenoids (for example, ß-carotene), present in fruit and vegetables, represent about 40% of the vitamin A consumed daily in western countries. A study of 8,861 subjects, including 2,310 who routinely drank juice, reported a 14% higher daily vitamin A intake among the routine orange juice drinkers compared to non-consumers (660μg retinol equivalent/day vs. 580μg retinol equivalent/day respectively).
A study that analysed blood carotenoids, found higher blood concentrations of alpha-carotene after the consumption of juice compared with consumption of raw or cooked whole vegetables. Fruit (and vegetable) juices typically have a high content of certain micronutrients whose bioavailability, as in the case of provitamin carotenoids, can be higher compared with corresponding raw or cooked whole fruits and vegetable.
Potassium and blood pressure
Potassium is found in significant quantities in 100% fruit juices, as well as vegetables, whole-grain cereals and legumes. The average daily intake of potassium in Europe is 2,463 to 3,991 mg/day in adults. The WHO suggests a potassium intake of 3,510 mg/day, based on a systemic review of the literature, with a view to controlling blood pressure and reducing the risk of cardiovascular disease, particularly stroke. Consumption of fruit juices in moderate amounts (around 150-200ml per day) and as part of a balanced diet could help consumers achieve recommended potassium intake levels and support the maintenance of normal blood pressure in the general population.
Energy density of fruit juices
Concerns have been raised as to whether the energy content of fruit juices (arising from fruit sugars) may modify the overall nutritional quality of the diet and contribute to a “nutrient dilution” effect. Studies have shown that, notwithstanding their energy density which is not high, fruit juice consumption is not associated with dilution of essential micronutrients such as vitamin A; indeed quite the opposite as they can contribute to meeting recommended intakes of these nutrients.
Phytocompounds such as carotenoids, particularly lutein, β-carotene and lycopene, as well as polyphenols are present in many 100% fruit juices. In citrus fruits, as most of the phenolic compounds and carotenoids are found in the skin, industrial pressing allows for a greater amount of phytocompounds to pass into the juice.