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Does iron supplementation improve exercise performance in the absence of anemia?

Iron deficiency anemia and iron deficiency without anemia are the most common diet-related micronutrient deficiency disorders in the world.

These conditions can impact the oxygen-carrying capacity of red blood cells and iron’s role in oxidative energy production. As a result, those with impaired iron status often experience reduced work capacity. The effects of iron-deficiency anemia on exercise performance are fairly well understood. However, studies also suggest that individuals with depleted body-iron stores who do not have iron-deficiency anemia may also experience changes in physical performance. The impact of simultaneous iron supplementation and aerobic training, especially in untrained subjects, remains unclear. A study conducted by Laura Pompano and Jere Haas (Cornell University) examined the individual and combined effects of iron supplementation and aerobic training on endurance performance in women with iron depletion without clinical iron deficiency. The study results, published in the February 2019 issue of The Journal of Nutrition, show for the first time that iron supplementation improves endurance performance at near-maximal intensities in untrained women exhibiting iron deficiency without anemia.

A total of 73 sedentary, untrained women exhibiting depleted iron stores but without clinical iron-deficiency anemia were randomly assigned into 4 groups: aerobic training plus supplemental iron, aerobic training plus placebo, no training plus supplemental iron, and no training plus placebo. Subjects were given either a placebo or iron supplement (100 mg of ferrous sulfate), which were taken 2 times a day throughout the 8-week study period. Subjects in the aerobic training group were instructed to pedal 5 days a week on an exercise cycle at 60 revolutions per minute at 75% or 85% of their age-predicted maximum heart rate, with the difficulty increasing each week. Graded exercise tests were performed at baseline and at week 8, along with simultaneous oxygen consumption measurements. Iron status was also measured at baseline and at study completion.

The results of this study indicate that aerobic training, iron supplementation, and their combination all result in significant improvements in several measures of submaximal exercise performance.

The results of this study indicate that aerobic training, iron supplementation, and their combination all result in significant improvements in several measures of submaximal exercise performance. However, the effects of iron supplementation were of the same magnitude as those produced from aerobic training, with or without iron supplementation. In other words, improving iron status had no impact on maximal oxygen uptake, a measurement used to assess aerobic fitness, but it did improve endurance at near-maximal intensities. It remains unclear as to why there was no additive benefit of iron supplementation and training together. Nonetheless, this study provides a deeper understanding of the impact of iron status on aerobic fitness in both trained and untrained individuals.  Particularly noteworthy is that the study results suggest that when previously sedentary women exercise at an intensity near their personal maximum, improvements in endurance performance are associated with improved iron status.

Reference Pompano LM, Haas JD. Increasing Iron Status through Dietary Supplementation in Iron-Depleted, Sedentary Women Increases Endurance Performance at Both Near-Maximal and Submaximal Exercise Intensities. Journal of Nutrition. 2019; 109. In Press. https://doi.org/10.1093/jn/nxy271

Hennigar SR. Ironing out the Relation between Iron Supplementation and Exercise Performance in the Absence of Anemia.  Journal of Nutrition. 2019; 109. In Press. https://doi.org/10.1093/jn/nxy288

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New Focus on Reducing Anemia in Adolescent Girls

By Marion Roche, PhD

The target set out by the World Health Assembly is to reduce the anemia in all women of reproductive age by 50% by 2025. Women make up about 3.5 billion in population on our planet. In order to reach this World Health Assembly target, it will be essential to address anemia in the 600 million adolescent girls in the world and recently their nutrition has been getting more attention.

The global birth rate has declined over the past decade, except when analyzing the rate for adolescent girls, with 17-20 million adolescent pregnancies per year. Eleven percent of all pregnancies are to adolescents and 95% of these adolescent pregnancies are occurring in developing countries.

Complications from pregnancy and child birth are the second greatest contributor to mortality for girls 15-19 years of age. Young maternal age increases the risk for anemia during pregnancy, yet adolescent women are less likely to be covered by health services, including micronutrient supplementation, than older women. Compared with older mothers, pregnancy during adolescence is associated with a 50% increased risk of stillbirths and neonatal deaths, and greater risk of preterm birth, low birth weight and small for gestational age (SGA) (Bhutta et al, 2013; Kozuki et al, 2013; Gibbs et al, 2012).

Reducing anemia in adolescents is often motivated by efforts to improve maternal and newborn health outcomes for pregnant adolescents; however, benefits for improving adolescent school performance and productivity at work and in their personal lives should also be valued.

Globally, iron deficiency anaemia is the third most important cause of lost disability adjusted life years (DALYs) in adolescents worldwide at 3%, behind alcohol and unsafe sex (Sawyer et al, 2012).

Adolescents have among the highest energy needs in their diets, yet in developing countries many of them struggle to meet their micronutrient needs. The World Health Organization recommends intermittent or weekly Iron Folic Acid Supplements for non-pregnant women of reproductive age, including adolescent girls. IFA supplementation programs have often been designed to be delivered through the existing health systems, without specific strategies for reaching adolescent girls.

I have heard adolescence referred to as “the awkward years” when individuals explore self-expression and autonomy, but it is also definitely an awkward period for public health services in terms of delivering nutrition, as we often fail to reach this age group.

There have been examples of programs going beyond the health system to reach adolescent girls, such as through schools, peer outreach, factory settings where adolescents work in some countries and even sales in private pharmacies to target middle and upper income adolescent girls.
The Micronutrient Initiative implemented a pilot project with promising results in Chhattisgarh, India where teachers distributed the IFA supplements to 66,709 female students once per week during the school year over a 2 year pilot.

It was new for the schools to become involved in distribution of health commodities, but engaged teachers proved to be effective advocates. There were also efforts to reach the even more vulnerable out of school girls through the integrated child development centers, yet this proved to be a more challenging group of adolescents to reach. Peer to peer outreach by the school girls offered a potential strategy. The current project is being scaled up to reach over 3.5 million school girls.

Adolescent girls have much to offer to their friends, families and communities beyond being potential future mothers. It is time to get them the nutrients they need to thrive in school, work and life.

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Anemia and Inflammation: A Research Dilemma

By Sheela Sinharoy

How does one estimate the prevalence of anemia in a population? Historically, this has been a fairly straightforward matter of testing hemoglobin levels and comparing them to set cutoff figures. However, as we learn more about the physiological effects of infection and inflammation, the validity of our estimates is called into question.

Monday’s symposium on the Biomarkers Reflecting Inflammation and Nutrition Determinants of Anemia (BRINDA) project highlighted some of these issues and potential approaches to address them. Parminder Suchdev of the Centers for Disease Control and Emory University began with an overview. He explained that the immune response triggers inflammation, which leads to temporarily decreased serum zinc and retinol and increased ferritin, transferrin receptor, and hepcidin. Although we know that these nutrients and biomarkers are affected by the inflammatory response, there is no widely accepted approach to effectively account for inflammation when analyzing and interpreting micronutrient data.

In order to address this gap, the BRINDA project team has been analyzing data from 15 countries representing all six WHO regions. Sorrel Namaste of Helen Keller International presented the key findings. Using C-reactive protein (CRP) and α-1 acid glycoprotein (AGP) as biomarkers of inflammation, they found that the prevalence of inflammation varied by country but was, on average, approximately 20% based on CRP and 40% based on AGP. Different methods of adjusting for CRP and AGP in the data analysis produced varying results, with a linear regression method being the most successful. These findings indicated that it is necessary to measure both CRP and AGP and to adjust for them in the analysis phase.

Next, Grant Aaron of Global Alliance for Improved Nutrition presented preliminary findings related to preschool aged children. In the sample, the burden of anemia was approximately 45%. Among children with anemia, 30% of the anemia was attributable to iron deficiency (unadjusted for inflammation). The age of the child, presence of inflammation, and anthropometric measures were associated with anemia in a majority of countries. Using an external correction factor, the proportion of anemia attributable to iron deficiency was adjusted to 35% for this age group.

Finally, Ken Brown of the Bill & Melinda Gates Foundation shared his interpretation of the findings. He emphasized the need for these biomarkers to establish the presence and magnitude of the problem, identify high risk sub-groups, and measure their response to interventions. This will require addressing practical challenges relating to specimen collection, analysis, and interpretation. He also pointed out that the need to collect biomarkers of any potential adverse effects of interventions. Ultimately, he encouraged the BRINDA team to make specific recommendations that other researchers can follow.

Overall, a major conclusion of the project thus far is that accounting for inflammation is necessary in order to improve the validity of anemia estimates. In acting on this conclusion, it will be important for researchers to ensure consistency in the parameters that are measured and to strengthen coordination between programs, evaluators and the academic community to build the evidence base.

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