Vitamin C Foods: A Practical Guide
Health benefits of Vitamin C
Vitamin C aids in the synthesis of collagen and elastin as well as other critical elements in our bone matrix, skin, tooth dentin, blood vessels, and tendons.
As an antioxidant, Vitamin C helps protect against oxygen-based damage to cells (free radicals), is required for fat synthesis and has antiviral and detoxifying properties.
Vitamin C protects you from cardiovascular diseases, cancers, joint diseases, cataracts as well as the common cold.
Vitamin C is an essential nutrient because humans (along with guinea pigs, fruit bats and other primates and mammals) can’t make their own. It is thought that humans lost their ability to make Vitamin C because it was so plentiful in our traditional diets.
Vitamin C is helpful for a variety of chronic health issues, including:
- high blood pressure,
- heart disease,
- elevated uric acid levels and gout,
- poor iron absorption,
- weak immunity, and
- poor memory.
Vitamin C supports your neurotransmitters
Vitamin C is also critical to help you make neurotransmitters that:
- stop you from peeing at night,
- prevent you from overeating,
- increase your sex drive,
- stop your hair from going grey, and
- boost your thyroid, adrenal and sex hormones.
History of Vitamin C
We have known since the 1500s that fresh food could prevent scurvy, which was a common killer of sailors on long voyages.
James Lind undertook the first documented controlled trial to establish that citrus fruits prevented scurvy.
Subsequently, Vitamin C was the first vitamin to be discovered in 1912 and isolated in 1928 and then synthesised in 1933.
Vitamin C deficiency conditions
With fresh food being more available, Vitamin C deficiency (scurvy) is rare today.
But you may still be at a higher risk of Vitamin C deficiency if you:
- are not able to eat fresh and minimally processed food (e.g. older people, low-income households or people with an eating disorder),
- smoke heavily or are dependent on alcohol or drugs, or
- have a health condition that makes it difficult to effectively digest your food (e.g. coeliac disease, ulcerative colitis or Crohn’s disease).
Vitamin C remains stable in dry powder form, but in food, it is highly unstable and degrades in response to heat, light and alkalinity. Losses during processing can range from 10 to 90%. Hence, it’s critical to focus on fresh food.
Our satiety analysis of people using the Nutrient Optimiser shows only a moderate satiety response when people consume food that contains higher levels of Vitamin C. People who consume more Vitamin C from their diet tend to consume around 15% fewer calories.
The relatively small satiety response to Vitamin C is likely because most people interested in optimising their nutrition are getting a reasonable intake of Vitamin C.
The Estimated Average Requirement for Vitamin C is set at 30 mg/day with a Recommended Daily Intake of 45 mg/day. The average consumption of Optimisers is much higher at 318 mg/day.
Vitamin C side effects, toxicity and overdose
While many people recommend high doses Vitamin C for a range of conditions, the Upper Limit of Vitamin C is set at 2000 mg/day due to gut tolerance. Too much supplemental vitamin C will send you to off to the toilet.
Chronic excess Vitamin C supplementation can lead to excess iron absorption (iron overload) which increases oxidative stress, Vitamin B12 deficiency and erosion of dental enamel.
Stretch Target for Vitamin C
Based on the satiety response, a reasonable stretch target from food could be 240 mg/day for women and 300 mg/day for men.
|nutrient||average||EAR||RDI||stretch (men)||stretch (women)|
|Vitamin C (mg)||318||30||45||300||240|
Availability of Vitamin C in the food system
Vitamin C availability has varied over time. Today, a significant amount of Vitamin C is used as an additive in food to prevent browning. It seems from the USDA data that there may have been an increase in Vitamin C fortification around 1970.
It is reasonably easy to get from the food system at levels to meet the EAR and RDI. However, if you want to achieve more optimal levels, you will need to go out of your way to focus on more nutrient-dense foods and meals.
Your absorption of Vitamin C depends on how much you’re consuming. Your stomach seems to regulate absorption based on demand.
Approximately 70%–90% of Vitamin C is absorbed in moderate intakes of 30–180 mg/day. However, at doses above 1 g/day, absorption falls to less than 50%. Unmetabolized Vitamin C is excreted in the urine.
It’s also worth noting that adequate Vitamin C is required to absorb non-heme iron successfully.
Can you get enough Vitamin C from meat?
Glucose and Vitamin C have similar chemical structures and compete for glucose transporters in the cell membrane. Both are escorted into the cells by the action of the hormone insulin. Thus, high levels of glucose in your diet means you will require more insulin and more Vitamin C to get glucose into the cell. Based on this logic, it appears that a diet with less glucose may require less Vitamin C.
Liver and organ meats contain some Vitamin C. However, other meats are typically assumed to have no Vitamin C and it is typically not measured (although fresh meat may still contain some).
While people consuming lots of fresh meat do not appear to develop scurvy, there are some anecdotal reports of people following a carnivorous diet developing symptoms of scurvy.
The minimum required intake of Vitamin C to prevent deficiency is fairly easy to obtain from an omnivorous diet with some fresh food. But if your diet has minimal glucose, this minimum requirement for Vitamin C may be even lower. Other nutrients commonly found in plant foods such as vitamin C, potassium, magnesium and calcium appear to be a more significant concern for people consuming only animal products.
It is not known whether the lower intake of Vitamin C on a carnivorous diet would affect iron absorption given that iron availability would be high.
Vitamin C rich food sources
- green peppers
- lemon juice
- lime juice
- sweet potato
The nutrient fingerprint below shows that it is easy to obtain the minimum required intake of Vitamin C. However, at the top of the chart we see that, because foods high in Vitamin C are typically plant-based, we tend to miss out on nutrients that are more common in animal-based foods (e.g. B12, selenium, choline, methionine and omega 3).
Nutritious meals to boost your vitamin C
If you are experiencing any of the symptoms of low vitamin C or are concerned that your current vitamin C intake is low, then you may be interested in our lists of vitamin C-rich foods and meals.
What you will get:
- Our Nutritional Optimisation Kickstart Guide.
- A list of the most popular 50 foods that contain more vitamin C.
- A list of 100 popular foods that contain vitamin C, and
- An even longer list of 150 common foods that contain more vitamin C to allow you to expand your nutrient-dense repertoire further.