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November 2009 Highlights of This Issue
More Evidence that Chocolate May Reduce Inflammation
Background Accumulating scientific evidence suggests that the genesis of atherosclerosis involves vascular inflammation. Consequently,
researchers are keenly interested in understanding whether certain lifestyle choices, such as optimal dietary patterns, might help modulate chronic
inflammation and ultimately decrease the risk of cardiovascular disease. One group of potentially beneficial dietary components consists of the flavonoids,
which belong to a larger category of compounds called polyphenols, many of which are potent antioxidants. Cocoa is an especially good source of flavonoids,
and several cell culture studies have provided evidence that cocoa exerts anti-inflammatory effects. However, few controlled human feeding trials have
focused on this relation. To lend more insight, a group of Spanish researchers evaluated the effects of chronic cocoa consumption on inflammation in a
group of older subjects at high risk of cardiovascular disease. Their results are published for the first time in the November 2009 issue of The American
Journal of Clinical Nutrition..
Study Design Subjects (19 men and 23 women; mean age: 70 y) were eligible to participate if they had diabetes or at least 3 other risk
factors for cardiovascular disease (eg, hypertension). After a 2-wk baseline period, each subject consumed daily either 500 mL skim milk (M) or 40 g soluble
cocoa powder mixed with 500 mL skim milk (C+M) for 4 wk. Participants then “crossed over” and consumed the other treatment for an additional 4 wk. In this
way, each subject served as his or her own control. Fasting blood samples and 24-h urine specimens were collected at baseline and after each treatment
period and were analyzed for a battery of inflammatory and cardiovascular biomarkers.
Results As hypothesized, several inflammatory markers were altered by cocoa consumption. For example expression of several adhesion
molecules [eg, very late activation antigen-4 (VLA-4) and CD40] found on the surface of white blood cells decreased during the C+M period. Similar results
were found for P-selectin and intercellular adhesion molecule-1 (ICAM-1), circulating biomarkers of inflammation. HDL-cholesterol concentration was higher
after C+M consumption than after the M treatment; higher HDL cholesterol is typically considered beneficial in terms of cardiovascular disease risk. No
other risk factors for cardiovascular disease were influenced by treatment.
Conclusions In summary, results of this study suggest a positive influence of cocoa on the modulation of inflammatory mediators in
older individuals at elevated risk of cardiovascular disease. The authors hypothesize that these effects may, in part, contribute to the overall benefits
of cocoa consumption in terms of atherosclerosis.
Reference Monagas M, Khan N,
Andres-Lacueva C, et al. Effect of cocoa powder on the modulation of inflammatory biomarkers in patients at high risk of cardiovascular disease.
American Journal of Clinical Nutrition 2009;90:1144–50.
For More Information For the complete article, please go to the following URL:
http://www.ajcn.org/cgi/content/full/90/5/1144
To contact the corresponding author, Ramón Estruch, please send an e-mail to restruch{at}clinic.ub.es.
Latino Youth Who Increase Fiber Consumption May Lower Risk of Diabetes
Background Escalating rates of obesity, especially in at-risk groups such as Latino youth, are of public health concern partly because
childhood obesity increases the risks of diabetes, metabolic syndrome, and cardiovascular disease. Although the etiology of childhood obesity and its
accompanying health problems is complex, environmental factors such as increased consumption of added sugars and decreased fiber intake are thought to be
involved. However, no study has simultaneously measured changes in these dietary variables and changes in adiposity and related disorders in at-risk youth.
As described in the November 2009 issue of The American Journal of Clinical Nutrition, researchers from the University of Southern California
examined these factors in overweight Latino youth. An accompanying editorial by Lupton delves further into the apparent relations between dietary
carbohydrate types and body fat distribution.
Study Design Children (48 boys and 37 girls) were 11–17 y of age, overweight or obese, and of Latino ancestry and had a family history
of type 2 diabetes. At the beginning of the study and ~1 y later, subjects were weighed and measured. Body composition was determined by using dual-energy
X-ray absorptiometry; amounts of adipose tissue beneath the skin (subcutaneous) and in the abdominal region (visceral) were estimated by using magnetic
resonance imaging (MRI). Insulin resistance was assessed by using a 2-h oral-glucose-tolerance test, and children not diagnosed with type 2 diabetes were
asked to participate in a frequently sampled intravenous glucose tolerance test. Dietary intake was estimated by using multiple 24-h recalls.
Results There was no overall relation between changes in total carbohydrate intake and changes in visceral adipose fat. However,
subjects who decreased their intakes of fiber during the study experienced increases in visceral adipose fat; the same was found between insoluble, but not
soluble, fiber and visceral adipose fat. More specifically, participants who decreased their total fiber intake had a 21% increase in visceral adipose
tissue, whereas those who increased their total fiber intake decreased their visceral adipose tissue by 4%. The researchers found no other associations
between nutrient intake and measurements of adiposity or blood glucose regulation.
Conclusions The authors concluded that “contrary to our hypothesis, decreases in sugar variables (including total sugar, added sugar,
fructose, and sugary beverages) were not related to improvements in insulin secretion” and proposed that a negative effect of sugar intake on insulin
secretion and responsiveness may have occurred earlier in life. Lupton lauded the significance of this study, in part because it went beyond simply
measuring body mass index (BMI)—it also examined body fat distribution. This is especially important given the fact that a change in visceral fat is
considered an independent risk factor for development of type 2 diabetes. Furthermore, Lupton’s editorial underscores the fact that all carbohydrates are
not created equal; instead, they have myriad and disparate effects when consumed.
Reference Davis JN,
Alexander KE, Ventura EE, Toledo-Corral CM, Goran MI. Inverse relation between dietary fiber intake and visceral adiposity in overweight Latino youth.
American Journal of Clinical Nutrition 2009;90:1160–6.
Lupton JR. Sugar and fiber intake and type of adiposity: are they related? American Journal of Clinical Nutrition 2009;90:1119–20.
For More Information For the complete article, please go to the following URL:
http://www.ajcn.org/cgi/content/full/90/5/1160
To contact the corresponding author, Jaimie Davis, please send an e-mail to jaimieda{at}usc.edu.
For the complete editorial, please go to the following URL:
http://www.ajcn.org/cgi/content/full/90/5/1119
To contact the corresponding author, Joanne Lupton, please send an e-mail to jlupton{at}tamu.edu.
Vitamin C Status in the United States: Should We Look beyond Scurvy?
Background Vitamin C is an essential nutrient that prevents scurvy and has been proposed to be important in decreasing the risk of
various chronic diseases. Nonetheless, clinical trials designed to determine whether supplemental vitamin C decreases the risk of chronic diseases have
generally produced disappointing results. Studies do show, however, that vitamin C status can be influenced by both dietary and genetic factors,
underscoring the concept that what might be adequate vitamin C intake for one person might be inadequate for someone else. Although scurvy is now rare in
the United States, there continues to be interest in whether vitamin C consumption is adequate to stave off other potentially vitamin C-dependent health
conditions. Two independent studies, published in the November 2009 issue of The American Journal of Clinical Nutrition, provide important
information concerning trends in vitamin C status and potential interindividual differences due to environmental and genetic factors. A corresponding
editorial digs deeper by questioning the adequacy of using only scurvy as a health outcome variable.
Study Design In the first study, researchers from the US Centers for Disease Control and Prevention compared vitamin C–related
data collected in the 1988–1994 and 2003–2004 National Health and Nutrition Examination Survey (NHANES). Specifically, serum concentrations and
dietary intakes of vitamin C were assessed and categorized as being adequate or inadequate. In the second report, researchers from the University of Toronto
studied 905 individuals to determine which type of glutathione S-transferase (GST) gene each one had and then investigated whether this affected risk
of vitamin C deficiency. GSTs are a group of enzymes in the body that can activate vitamin C.
Results Data from the more recent NHANES suggested that serum vitamin C concentrations were highest in children and older persons, with
women generally having higher concentrations than men. Plasma vitamin C concentrations in smokers were roughly one-third lower than those in nonsmokers, and
7.1% of Americans were classified as vitamin C deficient (a value lower than previously reported); recent vitamin supplementation or adequate dietary intake
decreased this risk. The Canadian researchers found that the presence of certain variations in the GST gene were associated with increased risk of vitamin C
deficiency in subjects consuming less than the Recommended Dietary Allowance (RDA) for vitamin C.
Conclusions The NHANES data are promising in terms of overall vitamin C status, although men and smokers may be at elevated risk of
deficiency. The Canadian study suggests that genetics might interact with diet to influence vitamin C status. In their accompanying editorial, Levine and
Eck praise these studies for providing basic information concerning the “x-axis” (vitamin C intake or blood concentration) but ask a question that is
rapidly becoming a common conundrum among nutritional scientists: what is the appropriate parameter for the y-axis (the dependent variable)? In sum,
they nudge researchers to consider looking beyond scurvy for meaningful health outcomes when it comes to studying vitamin C adequacy in the future.
Reference Schleicher RL,
Carroll MD, Ford ES, Lacher DA. Serum vitamin C and prevalence of vitamin C deficiency in the United States: 2003–2004 National Health and Nutrition
Examination Survey (NHANES). American Journal of Clinical Nutrition 2009;90:1252–63.
Cahill LE, Fontaine-Bisson B, El-Sohemy A. Functional genetic variants of glutathione S-transferase protect against serum ascorbic acid deficiency.
American Journal of Clinical Nutrition 2009;90:1411–7.
Levine M, Eck P. Vitamin C: working on the x-axis. American Journal of Clinical Nutrition 2009; 90:1121–3.
For More Information For the complete article by Schleicher et al, please go to the following URL:
http://www.ajcn.org/cgi/content/full/90/5/1252
To contact the corresponding author, Rosemary Schleicher, please send an e-mail to
rschleicher{at}cdc.gov.
For the complete article by Cahill et al, please go to the following URL:
http://www.ajcn.org/cgi/content/full/90/5/1411
To contact the corresponding author, Ahmed El-Sohemy, please send an e-mail to
a.el.sohemy{at}utoronto.ca.
For the complete editorial, please go to the following URL:
http://www.ajcn.org/cgi/content/full/90/5/1121
To contact the corresponding author, Mark Levine, please send an e-mail to
mark.levine{at}nih.gov.
Vigorous Activity May Be Especially Important in Curbing Obesity in Kids
Background Burgeoning childhood obesity rates represent a major public health concern worldwide, with an imbalance between calorie
consumption and physical activity laying the main etiologic foundation. However, which aspects of physical activity (or lack thereof) are most important in
staving off obesity are poorly understood. For example, very little is known about the independent effects of overall sedentary time and intensity of
activity on obesity risk in youth. To better understand how these factors, along with other indexes of physical activity, are independently and coordinately
related to body weight in children, researchers from the Medical Research Council Epidemiology Unit in Cambridge, United Kingdom, and University of East
Anglia, UK examined a large cohort of otherwise healthy British schoolchildren. Their results can be found in the November 2009 issue of The American
Journal of Clinical Nutrition.
Study Design Children (n = 1865; mean age: ~10.2 y) were recruited from 92 rural and urban schools in Norfolk, United Kingdom.
For 1 wk, each child wore an activity monitor to assess physical activity as well as inactivity; duration was recorded as min/d, and intensity as counts/min.
Anthropometric measurements included height, weight, body mass index (BMI), body fat percentage, fat mass, and fat-free mass. Children were also asked to
keep track of the frequency and duration of sedentary “screen” activities such as electronic games and television use for 7 d.
Results A relatively large percentage of children in this study were overweight or obese (19.8% and 25.4% in boys and girls,
respectively), and more girls than boys were overweight (P < 0.01). Girls also had more body fat than did boys and were more sedentary and less
physically active than boys (P < 0.01). For example, on average, boys were moderately active for 55 min/d, whereas girls were moderately active for
44 min/d; importantly, boys spent 27% more time engaged in vigorous activity than did girls. In addition, despite the fact that they were more active than
girls, boys reported more screen time than did girls: 110 compared with 71 min/d (P < 0.01). Regardless of sex and age, greater sedentary time was
related to increased fat mass (P < 0.05). However, this statistical relation disappeared when the researchers mathematically adjusted for physical
activity, especially time spent in vigorous activity.
Conclusions In summary, the study found that the more time both boys and girls spent being sedentary the more body fat they had. It
also showed that activity of moderate and vigorous intensity may be beneficial even in children who spend a lot of sedentary time sitting in front of
screens or playing computer games. Ekelund explains, "Our study results highlight the importance of moderate and vigorous physical activity in helping
children maintain a healthy body weight, as these types of activities are more strongly associated with body fat than sedentary time. However, we cannot
conclude that physical activity prevents unhealthy weight gain because children who are already overweight may be less likely to participate in more
vigorous activities. Although sedentary time may contribute to obesity in children, more strenuous activity may be needed to curb childhood obesity."
Reference Steele RM, van
Sluijs EMF, Cassidy A, Griffin SJ, Ekelund U. Targeting sedentary time or moderate- and vigorous-intensity activity: independent relations with adiposity in
a population-based sample of 10-y-old British children. American Journal of Clinical Nutrition 2009;90:1185–92.
For More Information For the complete article, please go to the following URL:
http://www.ajcn.org/cgi/content/full/90/5/1185
To contact the corresponding author, Ulf Ekelund, please send an e-mail to
ulf.ekelund{at}mrc-epid.cam.ac.uk.
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