Synbiotic may boost response to iron supplementation in female athletes: Study

Combining the synbiotic with iron supplements (140 mg per day of ferrous sulfate) led to significantly better iron status over eight weeks compared to ferrous sulfate plus placebo, report scientists from Marywood University (Scranton, PA).

“While this was a smaller sample [19 female athletes completed the study], if synbiotic supplementation can enhance the uptake of FeSO4 in ID [iron deficient] and IDEP [subclinical iron depleted] female athletes during repletion of Fe status, it could conceivably improve the Fe bioavailability of non-heme Fe sources and mixed meals (e.g. heme + non-heme sources of Fe),” ​wrote the researchers, led by Dr Diane DellaValle.

“Non-heme Fe is the most abundant source of dietary Fe worldwide, so using a synbiotic supplement or foods containing pre- and probiotics along with increased dietary Fe could aid in ameliorating ID in women around the globe.”​

The data was originally presented in 2018 at the American Society for Nutrition’s annual meeting in Boston, and the data is now published in the Journal of Dietary Supplements​.  

Iron deficiency​

Active women are especially susceptible to iron deficiency (ID) and subclinical iron depletion (IDEP), with surveys showing rates of IDEP in this population ranging from 25-52%. The consequences of this are “particularly relevant to athletic performance,”​ noted the researchers

Commenting on the significance of their findings, the researchers noted: “These results are important for female endurance athletes whose dietary patterns and physical training levels increase their risk of ID. In addition to screening the Fe status of female college athletes at the beginning of a season, athletes with a history of anemia or ID should receive counseling regarding Fe supplementation and high-Fe food choices, as well as serial monitoring of their Fe status (Hgb, sFer). ​

“Further, these results suggest that Fe supplementation, along with dietary adjustments (e.g. pre- plus probiotic consumption) may maximize Fe uptake.” ​

Study details​

Dr DellaValle and her co-workers recruited 20 female athletes with hemoglobin levels of 12.3 dL and serum ferritin (sFer) of 18.1 micrograms/L. The athletes were randomly assigned to receive 140 mg per day of ferrous sulfate with the Regular Girl synbiotic (Taiyo International, Inc.) or placebo for eight weeks.

The data indicated that, for the 19 athletes who completed the trial, compliance was good for both groups: 87% in the synbiotic group and 92% in the placebo group.

Iron status increased significantly more in the synbiotic group than in the placebo group, wrote the researchers.

“This RCT showed that after controlling for baseline sFer, supplementation with a synbiotic supplement along with low-dose Fe supplementation improved Fe stores in training female athletes,” ​they stated. “Taken together, these results indicate that along with once-daily, low-dose Fe supplementation it may also be beneficial for active females to receive dietary counseling on pre- and probiotic food choices, and/or synbiotic supplementation to maximize Fe bioavailability.”​

Decreasing the pH in the intestine​

Derek Timm, technical sales director for Regular Girl, told NutraIngredients-USA the company was, “very excited to see the strong results of this study on Regular Girl. ​

“Customers are already consuming Regular Girl to help with regularity, but these results showing our synbiotic combination has the added benefit of helping improve iron status,” ​added Timm. “This matters because iron deficiency is the leading nutrient deficiency worldwide and women need more than double the amount of iron compared to men.  ​

“Prebiotics have previously been shown to increase absorption of several minerals including calcium, iron and magnesium.  This study confirms the synbiotic combination of prebiotic fiber and probiotics in Regular Girl will help increase iron absorption.  This occurs because the fermentation of prebiotic fiber in the large intestine produces short chain fatty acids, which decrease the pH.  The decreased pH allows minerals in the large intestine to be better absorbed.  Overall, the reason Regular Girl helps with regularity is also the reason it leads to better absorption of iron.”​

Timm confirmed that the company is currently investigating a follow up study to confirm these findings and more deeply examine this connection.

“Iron is crucial”​

Commenting independently on the study, Dr Ralf Jaeger, managing member of Milwaukee-based Increnovo, LLC., told NutraIngredients-USA: “Probiotic strains have recently been studied for their ability to digest, absorb, and metabolize nutrients important to exercise performance and recovery/health status of those physically active, such as protein or carbohydrates and inorganic iron supplementation. ​

“Iron is crucial for oxygen transport, mitochondrial energy production, and cellular immune responses and has been shown to negatively affect physical performance and adaptation to training when low. In non-anemic female athletes with low iron stores receiving a daily supplement of 20mg of ferrous fumarate, ​L. plantarum 299v supplementation resulted in a more substantial and rapid improvement in iron status compared to iron alone [Axling et al., Nutrients 2020; 12(5):E1279​]​

“Sandroni et al. showed similar results with a higher dose of iron sulfate, supplementing a blend of one pre- and a single strain probiotic,” ​added Dr Jaeger.

Source: Journal of Dietary Supplements​
Published online ahead of print, doi: 10.1080/19390211.2021.1887423​
“Synbiotic Supplementation Improves Response to Iron Supplementation in Female Athletes during Training”​
Authors: A. Sandroni et al.