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Findings

Vitamin C is a powerful antioxidant that contributes to the formation and health of blood vessels, tendons, ligaments, bones, teeth and gums.¹ It helps the body absorb iron and recover from wounds and burns. Serious deficiency can lead to scurvy, which is now a rare condition in the Western world.

Fruit and vegetables are the main dietary sources of vitamin C, but it can also be taken as a supplement. In fact, vitamin C is taken more often than other supplements.²

This article provides an overview of vitamin C intake among Canadians and how levels are affected by supplement use (see the data).

According to the Institute of Medicine, the estimated average requirements for vitamin C range from 13 milligrams for toddlers aged 1 to 3 to 75 milligrams for adult men and 60 milligrams for adult women (Table 1). Because smokers have below-normal antioxidant levels and their bodies use vitamin C more quickly, their requirements are 35 milligrams higher than those of non-smokers. The recommended intake level maintains a near-maximum concentration of neutrophil (a type of leukocyte) in the blood, and minimizes the loss of vitamin C in the urine. The Institute of Medicine recommendations are not nearly as high as those of some other sources, which advocate intake as high as 400 or even 2,000 milligrams per day.³ This analysis, however, examines vitamin C intake in relation to the Institute of Medicine recommendations, which were set jointly by Canada and the United States and are used by Health Canada.⁴

Table 1
Estimated average daily vitamin C requirements, by age group and sex

Vitamin C from food

Three sources—fruit juice, fruit drinks and citrus fruits—accounted for 50% of the vitamin C that Canadians got from food in 2004; fruit juice alone made up 32% (Table 2).

Table 2
Main dietary sources of vitamin C, household population aged 1 or older, Canada excluding territories, 2004

Regardless of their age, sex, household income, level of education or province of residence, Canadians’ average dietary intake of vitamin C was well above the Institute of Medicine recommendations. In 2004, Canadians averaged 132 milligrams of vitamin C a day from food alone (Table 3). Quebec residents, whose fruit and vegetable consumption is highest,⁵ had the highest provincial dietary intake of vitamin C: a daily average of 144 milligrams.

Table 3
Vitamin C intake by supplement consumption and selected characteristics, household population aged 1 or older, Canada excluding territories, 2004

High averages, however, hide the substantial percentages of various groups whose vitamin C intake from food left them below the recommended levels. When smokers’ greater vitamin C requirements are factored in, 21% to 35% of men aged 19 or older had inadequate dietary intake; among women, the percentages ranged from 17% to 26%. Fewer than 10% of children and teens had inadequate dietary intake of vitamin C (Table 3).

Not surprisingly, a high percentage— 46%—of people who reported that they ate fruit and vegetables infrequently (no more than three times a day) had inadequate dietary intake of vitamin C. The percentages were also significantly high among people in the lowest income (25%) and education (35%) households and among those who were inactive during their leisure time (30%). Partly because smokers’ recommended intake is greater, over half (52%) of them had inadequate vitamin C intake from food. In fact, despite their greater requirements, smokers’ average dietary intake of vitamin C was lower than that of non-smokers. 

The people who took supplements containing vitamin C also tended to get more vitamin C from their diet than those who did not:  a daily average of 142 milligrams, compared with 126 milligrams. Thus, based on diet alone, those who did not take supplements were more likely than supplement consumers to have inadequate vitamin C intake (25% versus 17%) (data not shown)

Supplements

Just under a third (31%) of Canadians took supplements containing vitamin C in 2004 (Table 3). In general, the groups that had higher average dietary intake of vitamin C were also the most likely to take supplements—36% of people who ate fruit and vegetables more than six times a day did so, as did 38% of those with the highest household incomes, 34% of those who belonged to a household with at least one postsecondary graduate, 35% who were physically active, and 32% of non-smokers.

Quebec differed from the other provinces in that it had the highest dietary intake of vitamin C, but the lowest percentage of consumers of vitamin C supplements (Table 3).

Impact on intake

For the population as a whole, supplements provided 43% of vitamin C intake, twice as much as the main dietary source, fruit juice. And for the minority of the population (31%) who were supplement consumers, the percentage was nearly 70%. 

Supplement consumption raised Canadians’ overall vitamin C intake by 100 milligrams to an average of 233 milligrams a day. Among supplement consumers, total daily intake averaged 463 milligrams.

Despite the substantial increase in average milligrams a day, the overall effect of supplements was relatively modest, reducing the percentage of the total population with inadequate vitamin C intake by just 5 percentage points.  This is because more than two-thirds of Canadians did not take supplements, and those who did take them were likely to already have adequate dietary intake of vitamin C. Nonetheless, except among the age groups from 1 to 30, the reductions in inadequate vitamin C intake due to supplement consumption were significant (Table 3). The impact of supplement consumption was greater for smokers and for people who eat fruit and vegetables infrequently:  almost a 10-percentage-point reduction. 

As might be expected, few supplement consumers had inadequate vitamin C intake—2% overall, 5% among those who ate fruit and vegetables no more than three times a day, and 7% among smokers (Table 4). However, if the people who took supplements had not done so, based on their diet alone the percentages with inadequate intake would have been 17% overall, and 40% for smokers and infrequent consumers of fruit and vegetables.

Table 4
Percentage with inadequate vitamin C intake, by supplement consumption and selected characteristics, household population aged 1 or older who take vitamin C supplements, Canada excluding territories, 2004

Conclusion

More than 20% of Canadians do not get sufficient vitamin C from their diet. Roughly a third of the population takes vitamin C in the form of supplements. While supplements virtually eliminate inadequate intake among those who take them, the impact on the population as a whole is minimal.