The Numbers Talk This vitamin, ascorbic acid, is water-soluble and essential to humans. From immunity boosters to collagen production, there are other uses of vitamin C, but the body can’t synthesize it. So we have to get it from diet or supplements. This article presents statistics, recommendations, and benefits of vitamin C, specifically on the overall vitamin C status of the US population based on National Health and Nutrition Examination Survey (NHANES) data.
Why is vitamin C important?
Before we get into the intake numbers, let’s remind ourselves why vitamin C is so important in nutrition. Here are a few functions that this excellent antioxidant nutrient supports:
Immune activity: vitamin C supports various cellular functions of both innate and adaptive immune systems.
Collagen synthesis: It’s important for collagen synthesis, the structural protein needed for healthy skin, cartilage, tendons, ligaments, and blood vessels.
Iron absorption: Vitamin C enhances non-heme iron absorption (the form of iron found in plant-based foods).
Antioxidant properties: It’s a potent antioxidant that neutralizes free radicals and reduces oxidative stress in the body.
Wound healing: Since vitamin C is involved in collagen production, it’s also essential in wound healing. Vitamin C is indeed the foundation of good health.
Average Daily Intakes of Vitamin C in the U.S.
Let’s see how Americans are meeting their vitamin C needs. Average Daily Intakes of Vitamin C in the US According to the 2001-2002 National Health and Nutrition Examination Survey (NHANES) data, most Americans are getting enough vitamin C Here’s how average intake differs among groups:
Adult Males and Females From age 19 years and up,
Adult males consume around 105.2 mg/day.
Adult females of the same age group consume around 83.6 mg/day. These intake levels meet the Recommended Dietary Allowance (RDA) for most non-smoking adults.
RDA for adult males: 90 mg/day
RDA for adult females: 75 mg/day
It’s good to know that the mean intake is above or equal to RDA for both for general adult population because of fruits, vegetables, or even supplements.
Children and Adolescents (1-18 years) Mean vitamin C intakes range between 75.6 mg/day and 100 mg/day in children and adolescents according to age groups. These meet the RDAs for this age group according to the following:
1-3 years: 15 mg/day
4-8 years: 25 mg/day
9-13 years: 45 mg/day
14-18 years: 65-75 mg/day (depending on sex). So overall, American children and teens are getting enough vitamin C for their growth and immune health.
Vitamin C Intake for Infants and Toddlers
The 2001-2002 NHANES survey did not include any information on breastfed infants and toddlers, but most experts stayed in agreement that such infants and toddlers would get adequate vitamin C levels from breast milk; the infant formula is supplemented with vitamin C when given to the infant who is formula-fed, thereby covering all of the nutritional needs.
In fact breast milk is considered a perfect nutritional source in every possible respect for normal healthy growth in an infant, including vitamin C. Therefore, it can be said that the youngest members of the population will at most times likely meet their requirements and thus be nourished with this important nutrient during the early developmental period.
Role of Supplements in the Intake of Vitamin C
The intake of vitamin C supplementation by diet contributes significantly to the total vitamin C intake. This information came from NHANES 1999-2000:
35% of adults used multivitamin supplements such that most of these multivitamins included vitamin C;
12% non-using multivitamins but consuming vitamin C supplements, usually higher in amounts than contained in multivitamin supplements.
Assuming the findings of those surveyed in 1999-2002 by NHANES, for children:
Roughly 29%, or around 1 in 4, of children take some dietary supplement having vitamin C.
This trend in supplementation would suggest that many adults pursue their efforts to meet vitamin C intakes despite not receiving sufficient amounts through diet.
How Is Vitamin C Status Assessed?
More clearly, to know what an individual eats is another thing from judging whether the intake covers the needs for the body to receive and use adequate vitamin C. Status assessment is usually done by measuring plasma vitamin C concentrations.
Plasma Vitamin C Levels
It is the most commonly used measure of recent intake that determines the plasma serum concentration of vitamin C. Indeed very simple and readily available, this measure has its limitations: it reflects recent intake rather than long-term saturation in body tissues.
Leukocyte Vitamin C Concentration
Leukocyte (white blood cell) vitamin C concentration is a truer measure of tissue vitamin C and is regarded as much more reflective of the body's stores. However, this method is:
more difficult to evaluate,
less standardized across laboratories,
more variable.
Because of these shortcomings and due to the less accurate of plasma vitamin C in informing about tissue levels as compared to leukocyte vitamin C, plasma vitamin C measurement should be used more in clinical and research studies.
What Is An Excess Of Vitamin C?
which can be interpreted as the average daily intake level considered to be adequate to meet the nutrient requirements of nearly all healthy individuals, whereas at the same time, the Tolerable Upper Intake Level (UL) for vitamin C should also be given consideration:
For adults (19 years and older): 2,000 mg/day
For kids aged 1-3 years: 400 mg/day
For children aged 4-8 years: 650 mg/day
For children aged 9-13 years: 1,200 mg/day
For adolescents aged 14-18 years: 1,800mg/day
An individual ingesting more than these would have side effects.
diarrhea
nausea
abdominal cramps
patients with predisposition to kidney stones
However, high-label supplements should only be taken after consulting a healthcare practitioner, especially in the case of children and those with coexisting medical issues.
Best Sources of Vitamin C in the Diet
Supplements hold their worth, but always obtain it through whole foods. Vitamin C is found naturally in most appetizing and inexpensive products.
Among these, the best sources are:
Food Item Vitamin C (mg per serving)
Red bell pepper (1/2 cup) 95 mg
Orange (1 medium) 70 mg
Kiwi (1 medium) 64 mg
Broccoli (1/2 cup cooked) 51 mg
Strawberries (1/2 cup) 49 mg
Brussels sprouts (1/2 cup) 48 mg
Grapefruit juice (3/4 cup) 70 mg
Making every single one of these food items part of everyday meals is a deliciously simple yet completely natural way toward meeting the daily requirement without supplementation.
Risk Population Segments for Vitamin C Deficiency
Notwithstanding the positive intake statistics as a whole, certain groups are still considered to be at risk for vitamin C deficiency:
Smokers - Tobacco use increases oxidative stress and the turnover of vitamin C, which should be taken in larger amounts.
People with limited food variety - People consuming a very limited range of foods, having few fruits or vegetables, might have some deficiency of vitamin C.
Individuals with malabsorption syndromes - Conditions such as Crohn's disease or chronic diarrhea may hamper the absorption of nutrients.
Infants fed evaporated or boiled milk - These types of milk do not contain enough vitamin C, and a proper supplement should be provided to avoid deficiency.
The symptoms of vitamin C deficiency are fatigue, gum inflammation, and slow wound healing, with the extreme manifestation being scurvy—a condition that is associated with bleeding gums, bruising, and joint pains.
Conclusion: What the Data Tell Us about Vitamin C in America
NHANES data from 1999 to 2002 provide good insight into both vitamin C intake habits and vitamin C status in Americans. The take-home messages are as follows:
Most adults and children in the U.S. are meeting their vitamin C needs through food and supplements.
Supplement use is quite common, at least among adults, and is raising vitamin C intake well above that which could be obtained from foods alone.
Vitamin C status is generally assessed through plasma levels, but leukocyte concentrations give more accurate results, albeit these are more difficult to obtain.
While most of the population is getting enough vitamin C, certain populations remain susceptible to deficiency, including smokers and people with suboptimal eating habits.
While just avoiding deficiency is a worthy goal in optimizing vitamin C intake, maintaining health, immune function, and well-being are further considerations. Whether one is an orange lover, a strawberry fanatic, or the occasional multivitamin user, there are ways to support healthy vitamin C levels.
Reference
The reference for the data and statistics presented in this article is the following NHANES reports and scientific literature:
National Health and Nutritional Examination Survey, 1999-2002.
Dietary Reference Intakes for Vitamin C.
Studies on plasma and leukocyte vitamin C assessment.
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