IRON SUPPLEMENTATION IN HEALTHY BREASTFED INFANTS
Ziegler EE, Nelson SE, and Jeter JM. Iron supplementation of breastfed infants from an early age. Am J Clin Nutr. 2009;89:525–532.
Iron deficiency in infancy results in long-term neurodevelopmental impairments and affects millions of children globally. Infants are typically born with adequate stores of iron to last the first 4–6 months of life. This iron endowment coupled with iron ingested in formula or in breast milk is rapidly used during growth, and is generally replenished with the introduction of iron-containing foods. Breast milk itself contains very small amounts of iron, although this iron is highly bioavailable. Despite the high bioavailability of iron from breast milk, infants who are breastfed exclusively, in particular those with lower iron endowments may be at greater risk for iron deficiency. Ziegler et al. posit that iron supplementation during the first several months of infancy may prevent iron deficiency and improve iron endowment.
Infants whose mothers were breastfeeding exclusively to at least 5.5 months of age were randomized into either an iron-supplementation condition (n = 37) or placebo (n = 38). Infants were given daily drops of the iron-containing vitamin supplement (7 mg/d ferrous sulfate) or a vitamin placebo between the ages of 1 and 5.5 months. Infants were followed through the age of 18 months. Primary outcome measures included blood concentrations of ferritin, hemoglobin, and red cell indices. In general, the supplement was well-tolerated by the infants, with no mothers indicating difficulty in administering the drops. Two infants in the placebo condition developed iron deficiency prior to 5.5 months of age, and one infant in the iron-supplemented condition developed iron deficiency at 9 months of age. Plasma ferritin was significantly elevated in the iron-supplemented group during the period of supplementation, but this elevation did not last beyond the course of treatment. The authors conclude that iron supplementation from an early age in breastfed infants, while feasible, is only moderately effective in protecting an infant's iron endowment. They propose that screening and treatment would be more beneficial than universal supplementation.
Comment: Dr. Buchanan counters the proposal of Ziegler et al. for widespread screening for iron deficiency. He observes that the present study indicates that exclusive breastfeeding in early life is normally effective in preventing iron deficiency without supplementation. Widespread screening would be complicated by factors such as expense and uncertainty about which tests would be most appropriate in detecting iron deficiency.
Comment: Buchanan GR. Screening for iron deficiency during early infancy: is it feasible and is it necessary? Am J Clin Nutr. 2009;89:473–474.
COFFEE DRINKING IN MIDLIFE REDUCES RISK FOR DEMENTIA IN LATER LIFE
Eskelinen MH, Ngandu T, Tuomilehto J, Soininen H, and Kivipelto M. Midlife coffee and tea drinking and the risk of late-life dementia: A population-based CAIDE study. J Alzheimers Dis. 2009;16:85–91.
Coffee intake may be protective against cognitive impairments seen with aging. Coffee contains magnesium, caffeine, and antioxidant compounds, all of which may affect the progression of cognitive decline. Moderate consumption of coffee is associated with reduced risk for the development of type 2 diabetes, a known risk factor for dementia, and the contribution of magnesium from coffee could increase insulin sensitivity. Caffeine may have neuroprotective effects related to its actions as an adenosine receptor antagonist. Several longitudinal studies have associated coffee drinking in older individuals with reduced cognitive decline and decreased risk for Alzheimer's disease. Eskelinen et al. examined how coffee intake at midlife (∼50 yrs) impacted the development of dementia later in life (∼71 yrs) in Finns.
Participants in the Cardiovascular Risk Factors, Aging and Dementia (CAIDE) study were recruited from survivors of the North Karelia Project and the FINMONICA study. Baseline measurements were obtained between 1972 and 1987 (midlife) and reexamination measurements were taken in 1998, with an approximate follow-up time of 21 years (N = 1409; 62% women). Coffee intakes were assessed at midlife, and coffee drinking was categorized into low (0–2 cups/day), moderate (3–5 cups/day), and high (>5 cups/day). Cognitive status at follow up was determined primarily using the MMSE, with individuals scoring <24 examined further for diagnosis of dementia or Alzheimer's disease. Sixty-one individuals were diagnosed with dementia, 48 of whom had probable Alzheimer's disease. All data were adjusted for confounders including age, sex, education, depression, and ApoE-4 status. Low-level coffee drinkers had the highest rates of dementia and Alzheimer's disease as well as higher depression scores. Moderate coffee drinkers had an approximate 65% reduced risk for developing dementia and Alzheimer's disease relative to the low-level coffee drinkers, but there was no dose-dependent effect for coffee.
There are several limitations not addressed by the authors, and these limitations should be considered when interpreting the findings. The participants in this study had been enrolled in the North Karelia Project and the FINMONICA study, both long-term studies examining factors implicated in cardiovascular disease, a risk factor for dementia. The North Karelia Project, in particular, aimed to reduce cardiovascular disease through community-based intervention, and it was largely successful in reducing cardiovascular disease in Finns. It is not clear in the present paper to what degree participation in the intervention trial may have influenced the current findings. A main strength of this paper is the use of midlife coffee intakes, which avoids recall bias, and the long follow-up period of over 20 years. The authors suggest that the findings show a protective effect of coffee on cognitive status, and could lead to dietary interventions to modify the risk for dementia.
VITAMIN AND MINERAL USE IN CHILDREN IN THE UNITED STATES
Shaikh U, Byrd RS, and Auinger P. Vitamin and mineral supplement use by children and adolescents in the 1999–2004 National Health and Nutrition Examination Survey: Relationship with nutrition, food security, physical activity, and health care access. Arch Pediatr Adolesc Med. 2009; 163:150–157.
Vitamin and mineral supplements are commonly taken by both adults and children. However, the American Academy of Pediatrics does not recommend the use of such supplements in children over the age of 1 year if they are healthy and consume a varied diet. The present report by Shaikh et al. uses a Health Belief Model as a means of determining patterns directing vitamin use.
Under this model, individuals engage in a health-related action if such actions are perceived as beneficial in avoiding negative health conditions. Using this approach, the authors hypothesized that vitamin and mineral intake in children and adolescents would be higher in those at risk for nutritional deficiencies. They proposed that intakes would be higher in children with poor nutritional habits, lower food security, lower physical activity, lower access to healthcare, and who are underweight. Data for children and adolescents aged 2–17 years (N = 10, 828) from the NHANES 1999–2004 study were analyzed using vitamin and mineral supplement intake in the 30 days prior to NHANES interview as the main factor. Main outcome measures included demographics, food intake patterns, food security, physical activity, and healthcare access. Thirty-four percent of young people had used supplements in the 30 days prior to NHANES interview. In contrast to the hypothesized outcomes, higher supplement use was associated with white race, higher socioeconomic status, better nutritional habits, higher physical activity, better healthcare, and better self-reported health. Supplement use was higher in those with high food security and also in those who had low food security with hunger, but it was lower in those with moderate-to-low food security without hunger. The Health Belief Model approach to vitamin and mineral supplement use is novel, but the pattern of supplement use in children appears to be strongly associated with other health-promoting behaviors and with better socio-economic status, which is consistent with the literature on supplement use. High-risk populations that could potentially benefit most from vitamins and minerals are not receiving supplementation. In contrast, most of the children in this population who took supplements are at low risk for nutritional insufficiency.
SCIENCE ADVISORY: OMEGA-6 FATTY ACIDS AND CARDIOVASCULAR DISEASE
Harris WS, Mozaffarian D, Rimm E, Kris-Etherton P, Rudel LL, Appel LJ, Engler MM, Engler MB, and Sacks F. Omega-6 fatty acids and risk for cardiovascular disease: A science advisory from the American Heart Association Nutrition Subcommittee of the Council on Nutrition, Physical Activity, and Metabolism; Council on Cardiovascular Nursing; and Council on Epidemiology and Prevention. Circulation. 2009;119:902–907.
Recent focus on omega-3 fatty acids in relation to good health, particularly the focus on increasing the ratio of omega-3 to omega-6 fatty acids, has lead to the perception that omega-6 is detrimental to health. However, there is considerable evidence that intake of omega-6 fatty acids, linoleic acid in particular, has positive effects on cardiovascular health. Harris et al. in this science advisory from the American Heart Association present a review of the literature pertaining to omega-6 in the diet and risk for coronary heart disease.
Linoleic acid accounts for the majority of dietary omega-6 and comes primarily from vegetable oils such as corn or soy oil. After consumption, linoleic acid can be ultimately converted into arachidonic acid, an essential fatty acid, although this conversion rate is low. The main concern with linoleic acid intake and cardiovascular disease is that arachidonic acid is proinflammatory. However, arachidonic acid is the substrate for a variety of eicosanoids, some of which are proinflammatory and some of which are anti-inflammatory. At present, research shows improvement or no change in inflammatory markers with omega-6 intake. Higher intakes of omega-6 fatty acids are associated with improvements in cholesterol levels, improvements in insulin resistance, and lower blood pressure. Observational studies show a modest benefit of up to 10–12% energy intake from omega-6 in heart disease risk. Some intervention trials that replaced saturated fats with polyunsaturated fats (primarily from omega-6) showed 25–45% lowered risk for heart disease, although others showed no change in risk. The authors conclude that a diet containing 5–10% of energy from omega-6 polyunsaturated acids, in combination with a diet that is low in saturated fat and cholesterol can be beneficial in reducing risk for coronary heart disease. Furthermore, reducing omega-6 fatty acids in the diet would potentially increase risk for heart disease.
MODERATE-PROTEIN WEIGHT-LOSS DIETS AND BODY COMPOSITION
Layman DK, Evans EM, Erickson D, Seyler J, Weber J, Bagshaw D, Griel A, Psota T, and Kris-Etherton P. A moderate-protein diet produces sustained weight loss and long-term changes in body composition and blood lipids in obese adults. J Nutr. 2009;139:514–521.
Long-term weight loss and maintenance remain difficult goals for the majority of overweight individuals. The current dietary recommendations for weight management are high-carbohydrate, low-protein, low-fat diets. However recent work indicates that a higher proportion of protein in weight loss diets is more effective in short-term weight loss and spare-lean-mass loss in comparison with a high-carbohydrate diet regimen, but the long-term effects of these diets remain understudied. In the present report, Layman et al. examined the effects of a moderate-protein diet on weight loss, body composition, serum lipids, and weight maintenance in comparison with a more traditional high-carbohydrate diet.
Both reduced-calorie diets met the current recommendations for adequate protein and carbohydrate intake: protein >0.8 g/kg/day; carbohydrate >130 g/day. Thus, neither diet produced severe restrictions in macronutrient intake. The moderate protein diet contributed approximately 30% energy from protein, 30% energy from fat, and approximately 40% energy from carbohydrate. The higher carbohydrate diet contributed approximately 15% energy from protein, 30% energy from fat, and approximately 55% energy from carbohydrate. Participants between the ages of 40 and 56 years with a BMI greater than 26 (N = 130; 72 women) were randomly assigned to one of the two diets. In addition to receiving dietary instructions, participants were required to attend weekly meetings throughout the study period at which they received additional dietary information, were checked for dietary compliance, and were able to ask questions about the program. For the first 4 months of the trial, participants followed a reduced-calorie regimen (short-term weight loss) and for the remaining 8 months, they followed a weight-maintenance program. Total weight loss and compliance did not differ between the two conditions at 4 months. The participants in the moderate-protein condition had a greater loss of body fat in comparison with the higher carbohydrate condition, but the two groups did not differ in lean-mass loss. After 12 months, the participants in the moderate-protein condition continued to have a greater loss of fat mass relative to the higher-carbohydrate condition. The moderate-protein diet had higher participant compliance and a greater number of completers than the lower-protein condition. Over the course of the study, participants in the higher-carbohydrate condition showed improvements in HDL cholesterol levels and triacylglycerol levels. Participants in the moderate-protein condition also showed improvements in triacylglycerol levels and in total cholesterol : HDL cholesterol ratios and triacylglycerol : HDL cholesterol ratios. The authors suggest that these findings may have significance for long-term dietary management of metabolic syndrome or type 2 diabetes. Weight-loss diets frequently fail due to non-compliance. In the present trial, participants who were permitted to eat a greater portion of calories from protein had higher compliance and a greater number of individuals completing the trial. Higher-protein diets are more satiating than lower-protein diets and may make it easier for individuals to stay on a weight-loss regime for a longer period of time. Additionally, consuming a greater proportion of energy from protein during energy restriction leads to a greater loss in fat mass while conserving lean mass. The authors indicate that while energy restriction is the major factor in body-weight loss, the macronutrient composition of the diet can have significant impact on body composition and lipid profiles. The proportions of macronutrients in the present diets do not represent dietary extremes; they meet current recommendations for health, and would be relatively simple for individuals to implement.