peeled oranges in bowl on table

You probably already know that C is an important vitamin that we should be getting every day in our diets. You also know that when you feel a cold or flu coming on, quickly boosting your vitamin C levels helps your body to respond better.

But is diet enough? And if not, what else should we be doing?

How much vitamin C do we need?

For adults over 19, the recommended daily amount for vitamin C is 65 to 90mg a day. For a woman who’s pregnant the RDA is 85mg, 120mg if lactating.

Some researchers suggest that if we want to protect our immune systems, then we should be consuming around 200 to 400mg per day.

People who are hypertensive, smoke or have diabetes or osteoarthritis tend to have lower vitamin C levels. And as we age, our immune systems also don’t operate as well as they once did. Under these circumstances, we need more.

Consuming five varied servings of fruits and raw vegetables a day can provide more than 200 mg of vitamin C. But that means being consistent, which is difficult for many of us.

Vitamin C is found in citrus fruits, berries, potatoes, tomatoes, peppers, cabbage, Brussels sprouts, broccoli and spinach. Baobab, amalaki (or amla), camu camu, beetroot and a few other superfood powders are also high in vitamin C.

baby red tomatoes with sliced oranges

Where do we get it?

Fruits and vegetables high in vitamin C include:

  • Guavas;
  • Citrus fruits like oranges, grapefruit and lemon;
  • Kiwi fruit;
  • Pineapple;
  • Strawberries;
  • Bell peppers;
  • Chilli peppers;
  • Broccoli;
  • Kale;
  • Cauliflower;
  • Brussel sprouts;
  • Tomatoes; and
  • Mung beans.

Superfoods with the highest vitamin C include:

How does vitamin C work in the body?

When you look at the literature, it seems the verdict is still out on vitamin C and whether it really works for colds and flu. That’s research for you!

There does, however, seem to be agreement that:

  • Vitamin C levels decline during infections and stress. Supplementation seems to improve the body’s ability to resist infection by improving the functioning of the immune system.
  • Vitamin C has an anti-inflammatory effect. This is important because inflammation increases during a viral infection, and reducing the stress on the cells is essential to the body’s ability to cope with (and recover from) the infection.
  • Vitamin C is also believed to have an immunomodulatory effect. With sufficient C, our immune systems are better able to respond when needed.

Signs of Deficiency

There are several signs that someone may be low in vitamin C. Signs such as easy bruising, swollen or bleeding gums, painful swollen joints, poor immunity, low iron levels or anaemia, dry damaged skin and hair, fatigue, irritability, and unexplained weight gain may all indicate that someone’s vitamin C levels are low.

It’s also important to consider that people who are hypertensive, smoke or have diabetes or osteoarthritis tend to have lower vitamin C levels as well. And as we age, our immune systems don’t operate as well as they once did, so our bodies require more. Stress, surgery, and protein deficiency also increase our need for this essential vitamin.

vitamin c tablets on yellow background

So does supplementing work?

As we’ve mentioned, it seems there’s no clear answer when it comes to the common cold or flu. Several clinical trials with varying doses of ascorbic acid showed no significant prophylactic effect, but it did reduce the severity and duration of symptoms during the period of infection.

When it comes to COVID-19, preliminary studies indicate that many critically ill patients have low levels of vitamin C. In fact, there’s ongoing research into IV vitamin C therapy in COVID-19 patients to ascertain whether these high doses will help.

But before supplementing, it’s important to know a few things – especially if you’re wanting to go higher than the RDA.

It turns out that the body has a limited ability to absorb high doses of vitamin C. Because it’s water-soluble, the average adult will easily absorb around 100mg per day. But when the intake goes higher, the body doesn’t absorb it as efficiently. It gets rid of the excess through urine.

Vitamin C stays in the body for about 10-20 days; that’s how long it will take for your body to become depleted if you don’t have it in your diet. The more depleted you are, the more you can absorb at one time. So the amount you need depends on the state of your body.

What’s the best way to supplement?

In general, if you want to keep your levels as high as possible over time, then the advice is to take multiple doses (no greater than 200mg) throughout the day. In this way, the body (and more specifically the kidneys) should be able to absorb the entire dose.

If you’re really wanting to megadose with ascorbic acid (synthetic vitamin C), the suggested upper limit is 2000 mg daily. Take more and you may trigger gastrointestinal distress (bloating and cramping) and diarrhea.

Fortunately, supplementing with vitamin C is relatively safe and there are many types of supplements available. If you choose straight ascorbic acid, it should be buffered so as to be gentler on the stomach.

If you’re thinking of supplementing in higher doses, consider using liposomal vitamin C. The ascorbic acid is encapsulated in a fatty acid or liposome to allow for better absorption and tolerance of higher doses. It’s also a safer option for anyone who experiences gastrointestinal distress when taking vitamin C.

The takeaway from all of this is that firstly vitamin C should be part of your daily diet, and consuming fresh fruit and vegetables is a must for anyone wanting to be healthy. If this is a challenge for you, then it’s important to supplement in the right way.