The short answer
Vitamin C supports normal immune function, and a daily top-up suits anyone whose diet is light on fruit and veges, people who smoke, and anyone wanting easy support through winter. Taken every day, it shortened colds by about 8% in adults, though it doesn't stop most people catching one. Most people in New Zealand get the 45mg they need from food, so keep your total under 1,000mg a day. Not sure it suits you? Try our Supplement Finder.
In this article
Whether you're new to supplements, training through a busy winter or just trying to eat a bit better, vitamin C is one of the easiest nutrients to get right. This guide covers what the research shows for colds, how much you need, the best food sources and how to choose a supplement.
Should I take vitamin C?
Yes, if you don't eat much fruit and veges, you smoke, or you want an easy daily top-up through winter. People who smoke need more than everyone else. [1]
Does vitamin C stop colds?
Not for most people. Taking it every day shortened colds by about 8% in adults and 14% in children, but it didn't change how often people caught them. [2] For a five-day cold, 8% is around 10 hours.
The exception was people under short bursts of extreme physical stress, like marathon runners and soldiers in subarctic conditions, who caught fewer colds. That doesn't carry over to a normal training week. [3]
Does it help once I've got a cold?
Starting vitamin C after symptoms begin hasn't shown a consistent benefit. [2] If you're going to take it, take it daily. See your doctor if you have trouble breathing, can't keep fluids down or a cold drags on.
How much do I need?
45mg a day for adults. You need more if you're pregnant, breastfeeding or smoke. [1]
Stay under 1,000mg a day from all sources combined. That's the upper limit, not a target. [1]
More isn't better. Your body absorbs a smaller share as the dose goes up, and large doses can cause diarrhoea, nausea and stomach cramps. [4]
Can I get enough from food?
Yes, most people can. One medium kiwifruit gives you more than the daily 45mg. [4] Oranges, mandarins, capsicum, broccoli, tomatoes, potato and kūmara all help too. Cooking and long storage reduce vitamin C, so raw or lightly cooked is best. [4]
Check first
Who should check first?
Talk to your doctor before taking vitamin C supplements if you've had kidney stones, have kidney disease or have an iron overload condition. Vitamin C increases how much iron you absorb from plant foods. [4] If you're having cancer treatment, check with your oncology team first. Vitamin C can also affect some lab tests, so tell your doctor what you take.
Which vitamin C should I buy?
One that keeps your daily total under the 1,000mg upper limit, once you count any multivitamin, pre-workout or electrolyte drink you already take. "Natural" or "liposomal" doesn't mean better results for colds.
Our pick: Sanderson Ester-Plex 600mg Chewable Vitamin C
If you'd rather chew than swallow a capsule, this is the one we'd reach for. It's an orange-flavoured chewable that supports healthy immune function.
We chose it because it's a buffered vitamin C, designed to be gentler on the stomach than standard vitamin C, with fruit-derived co-factors including camu camu, acerola cherry, citrus bioflavonoids and rosehips.
Sanderson's directions are one to four tablets a day for adults, preferably with food. Count every tablet towards the 1,000mg daily upper limit, along with any multivitamin or other product you take, so one a day is where we'd start.
Contains sucrose, so take care if you have diabetes. Directions are for adults.
Want a plan built around you?
Inception Nutrition builds your immune support, supplements and lifestyle into one plan around your goals, your routine and the foods you like, with weekly check-ins wherever you are in NZ. Not sure where to start? Take their free metabolic audit. Not sure which product suits you? Try our Supplement Finder or email us at info@supplementsolutions.co.nz. No question is too basic.
References
4 sources
- 1.Australia and New Zealand Nutrient Reference Values: vitamin C Daily intakes, higher needs and the upper limit.
- 2.Cochrane: vitamin C for preventing and treating the common cold How often people caught colds, how long they lasted, and starting after symptoms.
- 3.Hemilä and Chalker (2013). Vitamin C for preventing and treating the common cold, full Cochrane review The extreme physical stress subgroup.
- 4.NIH Office of Dietary Supplements: vitamin C fact sheet for health professionals Food sources, absorption, side effects and interactions.
Sources shown: the research is linked in the references. Product details and doses come from the brand. Product suggestions show what’s available now. Last updated 22 October 2026.
This guide is general information, not a diagnosis or medical advice. Take products as directed, and check with a qualified health professional first if you're pregnant, breastfeeding, taking medication or managing a health condition.
