Orange juice and Covid-19: it won’t help and it may harm
Boosting our immune system has rarely felt more urgent than with the current coronavirus crisis, downplaying all other battles we were fighting to improve our health. This has brought back juices from being the food evil in the goal to reduce sugar intake to the food allied with healthy diets. Their popularity has grown mainly due to the generally assumed effects of vitamin C for protecting from a common cold — some of them caused by viruses belonging to the coronavirus group — and therefore to prevent Covid-19 infections. This extended belief has been reinforced by the still-unfolding results on the effects of megadoses of this vitamin to treat those infected with the virus.
For many, juices are the easy and fast way to get the vitamins of two or three fruits that otherwise they wouldn’t eat. Industry, always seeking chances to increase sales, has taken advantage of this situation and some companies like Moon Juice or Natali´s juice have designed special products claiming they can boost the immune system.
Among all the options available, orange juices have registered the highest sales growth (with about 50 mg of vitamin C by 100 g of fruit). The main reason for that is because, although there are fruits with higher vitamin C content than oranges, such as grapes (90 mg/100 g), they are considered the staple food enriched by this antioxidant. Only in the USA sales of orange juice jumped 70 % in the week ending March 21, 2020, compared to the same period in 2019. That’s a big turnaround from the prior trend of orange juice sales declining, which felt 40% from 2010 to 2019.
However, despite the interest to increase the vitamin C intake, the truth is that the results obtained so far on its effects for preventing a cold are inconclusive or negative. They have shown that among extremely active people, such as marathon runners, skiers, and army troops, taking at least 200 mg of vitamin C every day — about 400 mL of juice — appeared to cut the risk of getting a cold in half. For the general population, the effects are not that striking. The same intake of vitamin C only reduces the duration of cold symptoms by an average of 8% in adults and 14% in children.
A glass of juice not only provides more vitamin C and other beneficial micronutrients than one piece of fruit — polyphenols, minerals, vitamin A and B vitamins — but also levels of sugar similar to the most despised sugar-sweetened beverages. For example, a 330 mL can of coke has 39 g of sugar and the same quantity of orange juice has around 30 g. Other juices even exceed this concentration, such as those obtained from grapes with more than 54 g in 330 mL.
Although there are fewer investigations on the harmful effect of juices than sugar-sweetened beverages, those available have positively associated them with weight gain, type 2 diabetes, and all-cause of mortality. A recent publication part of the NutriNet-Santé study — aiming to better understand the determinants of eating behaviours — researchers from France found a link between natural juices and the incidence of cancer. The authors justify this impact on the accumulation of fat in the abdominal cavity and the rapidly absorbed sugars which increase insulin levels, both factors are independently associated with a variety of cancers. Most of these detrimental effects have been observed in those exceeding the recommended limits of 150 mL per day. Therefore, juices can have positive effects when consumed below the maximum recommended limits that prevent sugar to be a health problem.
Another important characteristic of juice is that by preparing them we eliminate the fiber of the fruit which helps to slower absorption of sugar in the intestine avoiding a fast spike of insulin which is one of the underlying causes of many diseases. Besides this benefit, fiber supports the growth of gut bacteria that convert fiber into short-chain fatty acids, with anti-inflammatory effects, and produce vitamins playing an essential role in the reinforcement of the immune system.
The high popularity that juices are having in the current pandemic is the consequence of looking at foods only by the health effects of one or several of their nutrients but not as a combination of all. Many other foods have been victims of this phenomenon that Michael Pollan popularized with the term nutritionism, which was originally credited to the Australian sociologist of science Gyorgy Scrinis. Under this lens, the fate of each food rises and falls with every change in the nutritional weather. In the case of juice, many articles have stated that they are just as bad as soda drinks when the spotlight is on sugar whereas this year many others encourage intake them to boost the immune system. The same can apply to other foods. For example, olive oil is considered a very healthful food because of the high monounsaturated fat and antioxidants it provides, but when the objective is losing weight, it is demolished.
It is clear that the more complex a problem is, the easier it is to engage people with simple and almost immediate solutions, but the juice is not a magic potion to prevent Covid-19. To face the virus infection, we should have sufficient energy, nutrients and a balanced diet — no individual nutrient, food or supplement will boost immunity, or will prevent getting highly infectious viruses like Covid-19. When referring to juice the recommendation is to have not more than 150 mL per day, to have it with a meal so it doesn’t make blood sugar go up too quickly and favour fruit intake over juice, just the same as before pandemic.
