As the pandemic goes on and winter approaches in the northern hemisphere, incorporating a cheap, easy and accessible immune system booster has never been more crucial. When we think of nutrients that provide some protection against the common cold and influenza, we often think of vitamin C in the form of orange juice or maybe a hot lemon tea. But which of the two is higher in vitamin C and what are the alternatives?

the orange is not the pinnacle of vitamin C-rich food

A powerful antioxidant that protects cells and reduces free radical damage, vitamin C is often associated with boosting the immune system in various ways, effectively reducing the risk of infection and helping to fight some of them, such as the common cold. As the world continues to learn more about COVID-19, contracting both a cold or flu and coronavirus at the same time is currently said to be very possible, which is why supporting the body's defences is vital right now.

The recommended daily intake (RDI) of vitamin C for adults is between 70 to 90 milligrams. Upwards of 2000 milligrams is not recommended due to various potential side effects, but even 500 grams should be taken with caution as you run the risk of short-term side effects, such as diarrhea, or long-term and more serious side effects, such as kidney stones. These high levels can be reached simply by taking one or two vitamin C supplements per day, so it's important to check dosage per capsule and consult a health professional to find out what's right and safe for you.

In terms of oranges versus lemons, there's little difference in vitamin C content. In every 100 grams, oranges contain around 50 milligrams, while lemons contain around 55 milligrams. A large orange usually weighs over 100 grams, so one or two large oranges would provide RDI without the sourness of lemons, higher fibre (when you eat the pulp), more nutrients overall (e.g. vitamins A, E, potassium), but unfortunately up to seven times more sugar than the same serving of lemons. Besides containing less sugar, citric acid is higher in lemons – a point to consider if you want to reduce the risk of kidney stones. But if citrus fruits really aren't your thing, there are tastier alternatives.

Unbeknownst to many, the orange is not the pinnacle of vitamin C-rich food. Guavas have almost five times the vitamin C content as an orange or lemon at the same volume (in size it's closer to a lemon), though it's hard to find outside of tropical areas. Two widely available and edible options are red capsicum (red bell pepper) and kiwifruit (the green Hayward variety), with vitamin C at three and 1.5 times that of oranges, respectively.

Although food sources of vitamin C are said to be more easily absorbed by our bodies, vitamin C supplements have temporarily been given the green light by some health professionals in light of the current pandemic and our track record in consuming sufficient daily servings of fruit and vegetables.