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September 2009 Highlights of This Issue
Systematic Review Finds that Conventional Foods Are Just As Nutritious As Organics
Background "Organic" foods are those grown and produced according to specified standards that limit pesticide and herbicide use in crop
production and drug use in livestock rearing and also emphasize minimal environmental impact. Despite the higher price point of organic foods, their sales
have been booming as a result of claims and perceptions that organic foods are more nutritious, healthier, and tastier than nonorganic foods and that their
production does less damage to the environment than that of nonorganic foods. But what is the scientific evidence that organic foods are in fact more
nutritious than their less expensive counterparts? To help answer this question, researchers at the London School of Hygiene & Tropical Medicine carefully
combed through the published literature to identify and evaluate all the research that has been published on this topic. Their methods and findings can be
found in the September 2009 issue of The American Journal of Clinical Nutrition.
Study Design These researchers conducted a systematic review of all published studies that reported the chemical analysis of foodstuffs
produced using organic or conventional methods over the past 50 years (between 1958 and 2008). It is noteworthy that the quality of research and reporting
in this area was found to be extremely variable, which calls into question the validity of the conclusions drawn by many previously published studies on
this topic. From a total of 52,471 articles, the researchers identified 162 studies related to nutrient content of organic and conventionally produced foods,
of which 55 were of satisfactory quality. The contents of nutrients (such as vitamin C, calcium, and zinc) and other nutritionally relevant substances (such
as phenolic compounds) reported in satisfactory quality studies were compared between organically and conventionally produced foodstuffs. To help prevent
researcher bias, an independent expert review panel was constituted to oversee and advise on issues related to the conduct of the review, and the results
and conclusions were reviewed by 5 additional subject experts.
Results The results indicated no evidence of a difference between organic and conventional crops in terms of their content of vitamin C,
magnesium, calcium, potassium, zinc, or copper. Conventional crops were found to contain more nitrogen than did organics, and organic crops had higher
phosphorus and acidity content than did conventional crops. When only animal-source foods were considered, the researchers found no evidence of a difference
in nutrient content.
Conclusions These scientists concluded that "there is no evidence of a difference in nutrient quality between organically and
conventionally produced foodstuffs." They also propose that the claim of benefits to public and environmental health of organic growing and processing
methods warrants further systematic review and assert that future research in this area would be enhanced by improved scientific protocols and reporting
procedures.
Reference Dangour AD,
Dodhia SK, Hayter A, Allen E, Lock K, Uauy R. Nutritional quality of organic foods: a systematic review. American Journal of Clinical Nutrition
2009;90:680–5.
For More Information For the complete article, please go to the following URL:
http://www.ajcn.org/cgi/content/full/90/3/680
To contact the corresponding author, Alan Dangour, please send an e-mail to:
alan.dangour{at}lshtm.ac.uk.
Effects of Vitamin A Supplementation Differ Depending on Vaccination Status
Background Vitamin A deficiency remains a major public health concern in developing countries, and the World Health Organization
recommends that high-dose vitamin A supplements be given to all children aged 
6 mo. However, studies assessing
the effect of vitamin A supplementation (VAS) from 1 to 5 mo have generally found no effect on mortality, whereas the majority of trials in the 1980s and
early 1990s studying older infants and children reported benefits. It has been proposed that the efficacy of VAS in reducing mortality may be modified by
whether the child has already received vaccinations. Sex may also influence the outcome. To test this, researchers examined if VAS was associated with
reduced mortality in children who had been vaccinated for bacilli Calmette-Guérin (BCG; usually given at birth), diphtheria-tetanus-pertussis (DTP;
recommended at 2, 4, and 6 mo of age), or measles (MV) as their most recent vaccination. They hypothesized that a negative effect of VAS with DTP would be
stronger in girls than boys. Details concerning this study can be found in the September 2009 issue of The American Journal of Clinical Nutrition.
Study Design At enrollment, children (n = 11,722) were randomly assigned to receive either high-dose vitamin A supplements or
placebo every 4 mo for 2 y. Vaccinations were not provided by the researchers but through routine health services, but information concerning when
vaccinations were given was recorded annually by the researchers. Mortality was also assessed.
Results VAS appeared to benefit only children with no record of vaccination at enrollment. Among vaccinated children, the effect of VAS
on mortality during a particular 4-mo interval differed between boys and girls, such that it was associated with increased mortality among MV-vaccinated
girls, who were likely to have also received at least one vaccination for DTP during those 4 months.
Conclusions The present study adds evidence that the effect of VAS is dependent on vaccination status and that, while VAS may reduce
mortality in many situations, it may be harmful in some specific subgroups of infants and young children. Although these associations may not be causal,
they are disturbing, and there is a need to more carefully assess this interaction. In an accompanying editorial, Stephensen and Livingston suggest that
high-dose supplements may have risks not seen for low-dose supplementation or fortification. They urge further studies to determine the physiologic
mechanisms by which vitamin A influences immune response in children so that this potential adverse interaction with vaccines can be evaluated from a
mechanistic standpoint and that public health recommendations can be developed to maximize the benefits while giving appropriate consideration to the
risks.
Reference Benn CS, Aaby P,
Nielsen J, Binka FN, Ross DA. Does vitamin A supplementation interact with routine vaccinations? An analysis of the Ghana Vitamin A Supplementation Trial.
American Journal of Clinical Nutrition 2009;90:629–39.
Stephensen CB, Livingston KA. Vitamin supplements and vaccines: maximize benefits, evaluate potential risks. American Journal of Clinical Nutrition
2009;90:457–8.
For More Information For the complete article, please go to the following URL:
http://www.ajcn.org/cgi/content/full/90/3/629
To contact the corresponding author, Christine Benn, please send an e-mail to
cb{at}ssi.dk.
For the complete editorial, please go to the following URL:
http://www.ajcn.org/cgi/content/full/90/3/457
To contact the corresponding author, Charles Stephensen, please send an e-mail to
charles.stephensen{at}ars.usda.gov.
Studies Do Not Support Unhealthful Relation between Animal Foods and Breast Cancer
Background Breast cancer is the 7th leading cause of mortality in the United States and results in approximately 41,000 deaths each
year. Although genetic factors are important, there is considerable evidence that breast cancer risk is related to modifiable lifestyle factors, such as
physical activity, body weight, alcohol intake, and dietary choices. For instance, epidemiologic studies suggest that a "Western" diet high in animal foods
is related to increased risk. Conversely, conjugated linoleic acid (CLA) found primarily in beef and milk decreases mammary cancer initiation and promotion
in animals; CLA consumption from supplemental sources also lowers body fat, which might help decrease cancer risk even more. The September 2009 issue of
The American Journal of Clinical Nutrition reports the results of 3 human studies designed to better delineate the relation between animal foods and
breast cancer risk. An accompanying editorial asks the following: "Meat, dairy, and breast cancer: do we have an answer?"
Study Design In the first study, which was a controlled dietary intervention trial conducted in the United States, 35 obese
postmenopausal women with type 2 diabetes received CLA supplements (~7.4 g mixed isomers/d) or a control supplement (safflower oil) each for 36 wk;
adiposity was assessed. In another study, researchers examined the association between CLA intake from natural sources and breast cancer incidence in a
large (n = 61,433) cohort of initially cancer-free Swedish women for 17.4 y. The third study assessed whether the consumption of meat, eggs, and
dairy products was associated with breast cancer risk in a very large (n = 319,826) group of healthy European women followed for 8.8 y.
Results In the first trial, CLA supplementation reduced body mass index (BMI; P < 0.0022) and lowered total adipose mass
(P = 0.0187). The epidemiologic study conducted in Sweden provided no evidence of a protective effect of dietary CLA intake on breast cancer
development. Similarly, the large European epidemiologic study found no consistent association between breast cancer risk and consumption of any of the
animal-derived food groups they studied.
Conclusions These studies provide no evidence that animal-food consumption increases (or decreases) risk of breast cancer, although
CLA supplementation may decrease adiposity (a major risk factor for this disease). In their editorial, Linos and Willett remind us that these studies did
not assess the relation between animal-food intake during early life and later breast cancer, a likely important piece of the puzzle. Nonetheless, they
conclude, "These data are sufficient to exclude any major effect of consuming these foods during midlife or later on risk of breast cancer." Perhaps we
finally have the answer to this long-standing question.
Reference Larsson SC,
Bergkvist L, Wolk A. Conjugated linoleic acid intake and breast cancer risk in a prospective cohort of Swedish women. American Journal of Clinical
Nutrition 2009;90:556–60.
Norris LE, Collene AL, Asp ML, et al. Comparison of dietary conjugated linoleic acid with safflower oil on body composition in postmenopausal women with
type 2 diabetes mellitus. American Journal of Clinical Nutrition 2009;90:468–76.
Pala V, Krogh V, Burrino F, et al. Meat, eggs, dairy products, and risk of breast cancer in the European Prospective Investigation into Cancer and Nutrition
(EPIC) cohort. American Journal of Clinical Nutrition 2009;90:602–12.
Linos E, Willett W. Meat, dairy, and breast cancer: do we have an answer? American Journal of Clinical Nutrition 2009;90:455–6.
For More Information For the complete article by Larsson et al, please go to the following URL:
http://www.ajcn.org/cgi/content/full/90/3/556
To contact the corresponding author, Susanna Larsson, please send an e-mail to
susanna.larsson{at}ki.se.
For the complete article by Norris et al, please go to the following URL:
http://www.ajcn.org/cgi/content/full/90/3/468
To contact the corresponding author, Martha Belury, please send an e-mail to
mbelury{at}ehe.osu.edu.
For the complete article by Pala et al, please go to the following URL:
http://www.ajcn.org/cgi/content/full/90/3/602
To contact the corresponding author, Vittorio Krogh, please send an e-mail to
vittorio.krogh{at}istitutotumori.mi.it.
For the complete editorial by Linos and Willet, please go to the following URL:
http://www.ajcn.org/cgi/content/full/90/3/455
To contact the corresponding author, Eleni Linos, please send an e-mail to
linos{at}stanford.edu.
More Evidence that High-Fiber Foods Prevent Chronic Disease
Background The USDA Dietary Guidelines for Americans encourages us to consume 3 or more servings of whole-grain products, 1–2.5
cups of fruit, and 1–4 cups of vegetables each day partly because these foods provide dietary fiber. Dietary fiber is important in maintaining
gastrointestinal health, and many studies show that higher consumption decreases risks of chronic diseases such as cardiovascular disease, some cancers, and
type 2 diabetes. Not all studies support these associations, and conflicting results are probably due to differences in dietary intake methodologies,
inadequate statistical control of confounding variables, and small sample sizes. However, results from 2 large-scale studies designed to investigate the
relation between high-fiber foods and chronic disease, published in the September 2009 issue of The American Journal of Clinical Nutrition, provide
important insight into how high-fiber food choices might affect risks of hypertension in men and breast cancer in women.
Study Designs In their research concerning breast cancer, Park and colleagues studied postmenopausal women (n = 185,598) who did
not have cancer at the time of enrollment. Their study estimated fiber consumption and assessed breast cancer incidence over an ~7-y period. Further
information was obtained concerning the type of tumors (ie, estrogen and progesterone hormone responsiveness) in women who were subsequently diagnosed with
breast cancer. Similarly, Flint and coworkers followed for 18 years 31,684 male health professionals who, at baseline, did not have hypertension.
Whole-grain and fiber intakes were calculated, and incident hypertension was reported by each participant over the course of the study. In both studies,
nondietary variables that might be coincidently related to the outcome (eg, smoking and body mass index) were controlled for mathematically.
Results Results from both studies suggest that greater intake of high-fiber foods is inversely related to risk of chronic disease.
Higher dietary fiber intake was related to lower breast cancer risk: women who consumed the most fiber had a 13% lower risk than those who consumed the
least (P for trend = 0.02). This relation was even stronger in women with hormone-nonresponsive tumors: high fiber intake reduced the risk by 44%
(P for trend = 0.008). Similarly, whole-grain intake decreased the risk of hypertension by 19% (P < 0.0001); individuals in the highest
whole-grain consumption group ate ~11 g/d more fiber (the amount in ~4 slices of whole-wheat bread) than those in the lowest whole-grain consumption
group.
Conclusions These studies lend significant support to the recommendation to increase consumption of fiber-rich foods. In both studies,
mean daily fiber intake was ~18 g/d, whereas experts recommend we consume 25–38 g/d. Including more whole-grain foods, fruit, and vegetables in one's
diet will go a long way to achieving that goal.
Reference Flint AJ, Hu FB,
Glynn RJ, et al. Whole grains and incident hypertension in men. American Journal of Clinical Nutrition 2009;90:493–8.
Park Y, Brinton LA, Subar AF, Hollenbeck A, Schatzkin A. Dietary fiber intake and risk of breast cancer in postmenopausal women: the National Institutes of
Health–AARP Diet and Health Study. American Journal of Clinical Nutrition 2009;90:664–71.
For More Information For the complete article by Flint et al, please go to the following URL:
http://www.ajcn.org/cgi/content/full/90/3/493
To contact the corresponding author, Alan Flint, please send an e-mail to
aflint{at}hsph.harvard.edu.
For the complete article Park et al, please go to the following URL:
http://www.ajcn.org/cgi/content/full/90/3/664
To contact the corresponding author, Yikyung Park, please send an e-mail to
parkyik{at}mail.nih.gov.
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