Handbook of Vitamin C Research

Vitamin C Intake 271exposure [98-101]. Younger children may be unaware of random smoke exposure and whileonly 35% of children in the US younger than 18 years live in homes where residents orvisitors smoke [102], a national survey reported that virtually all children of similar ages haveat least low levels of cotinine in their system [103]. Indeed, data from this same surveydocumented that 87.9% of non-tobacco users had detectable levels of serum cotinine [104].To sum up, it is more logical to expect that measurement of children‘s exposure to acomponent of tobacco smoke would better predict ETS than would a self-reported smokeexposure. Consequently, we agree with Jarvis et al. [105] who recommend that investigatorsshould supplement or replace questionnaire data with quantitative measures of actual smokeexposure.One result of this study has been the confirmation of previous findings that showexposure to ETS results in reduced levels of vitamin C intake due to decreased consumptionof food with high vitamin C content [70-79]. Previous studies have included mainlypreschool children and adults so our population of children aged 2-13 years can extendconclusions for an understudied age group. As to whether the reduced intake of vitamin C inour subjects could have any clinical significance, the probability is unlikely. Both LEX andHEX children consumed well in excess of National Research Council required amounts ofvitamin C (20-45 mg/d) [95]. In fact, we have shown that blood levels of ascorbate in ourpopulation of children are overwhelming in the normal to saturated categories [106].However, not all children are as well fed as ours and suboptimal to low vitamin C status inother populations has been implicated as a major risk factor in cardiovascular diseases andall-cause mortality [107].The principal finding in this study is related to meal pattern. To our knowledge, this isthe first report of the effect of ETS on vitamin C intake during the daily dietary regimen.Breakfast provided the greatest amount and percentage of total vitamin C intake for the dayin both LEX and HEX children. This result is unsurprising since fruits and juices aretraditionally served at this meal. Likewise, lunch and dinner provided lesser but similaramounts of vitamin C for both groups. The unexpected finding was the contribution of snacksto the amount of daily vitamin C intake, which was 15% in HEX children and 26% in LEXchildren. It is well documented that snacking behavior among US children has increaseddramatically over the past 25 years [108]. Snacks are generally considered of low dietaryquality and major sources of fat and calories disposing toward overweight and obesity [109-111]. While these conclusions may often be valid our study shows that snacks can also be amajor source of an important nutrient, indeed one-fourth of the daily intake of vitamin C isprovided for children not exposed to ETS. A recent study examining snacking patterns in USadults shows a positive relationship with eating frequency and vitamin C intake [112]. In fact,when snacks contain nutrient dense foods, higher intake of such beneficial nutrients as folicacid, calcium, magnesium, iron, potassium and dietary fiber have been documented in studieswith adolescents [113] and adults [112, 114].Closer examination of snacking behavior reveals that snack #1 (midmorning) providedmuch more vitamin C than did snack #2 (mid-afternoon) or snack #3 (evening). A largepercentage of our study groups attends preschool and elementary school and brings to schoolwith them a snack prepared at home. Our data indicate that children from LEX householdsbring snacks with high vitamin C content, while children from HEX households bring snacks