Welcome to the June 2025 issue of Research Extracts. “The Extracts” is designed to keep busy practitioners and savvy consumers up to date on the latest research on diet, nutrients, botanicals, the microbiome, the environment, and lifestyle approaches to good health and wellness. Our medical team, including NDs, RDs, MS biology, MS chemistry, an LAc, and a Certified Specialist in Sports Dietetics (CSSD), summarizes the essence of several interesting recent studies. 

In this issue: (1) Movement Moment: iron deficiency in female athletes, (2) nutrient deficiencies in GLP-1 users, (3) exercise timing and sleep, and (4) sugar-sweetened beverages and sperm quality. 

Movement Moment: Iron Deficiency, Supplementation, and Sports Performance

In female athletes, iron deficiency prevalence ranges globally from 9 to 60%. Iron supports key biological functions for peak sports performance through the production of red blood cells, oxygen transportation and uptake, and ATP production for energy. Females typically have a higher rate of iron turnover than males, usually due to menstrual cycle blood loss, which can contribute to up to 10 mg of iron lost per cycle. 

In this review of 23 articles, researchers aimed to characterize the effects of iron deficiency and iron supplementation on sports performance in high-level female athletes. 

The research shows that the impact of iron deficiency largely depends on its severity, which can range from non-anemic iron deficiency, where iron stores are reduced to iron deficiency anemia that compromises red blood cell production and oxygen delivery due to reductions in blood hemoglobin – crucial for tissue oxygenation and subsequent recovery.

Iron deficiency has been shown to consistently impair endurance performance, as athletes who are iron deficient will require more energy to complete the same endurance task. However, performance decrements can depend on the stage of iron deficiency because maximal aerobic capacity may not be affected until iron deficiency anemia is present. 

Endurance performance was found to be compromised by 3-19% compared to iron-sufficient counterparts, likely due to decreased tissue oxygenation. In one study, both iron-deficient and iron-sufficient runners followed an eight-week training program; iron-deficient runners completed a 2,400-meter time trial that was, on average, 36 seconds slower than that of iron-sufficient runners at the end of the eight weeks. 

Note: Thorne’s Iron Bisglycinate is NSF Certified for Sport® and provides 25 mg of elemental iron per capsule. Ferrasorb provides comprehensive nutritional support with iron bisglycinate, B vitamin cofactors, and vitamin C for enhanced iron absorption. 

Contributed by Maura Donovan, MS, RD, CSSD

Reference

Nutrient Deficiencies In GLP-1 Weight Loss Drug Users

In a cross-sectional analysis, nutrient intakes were assessed in 69 participants who had been on GLP-1 agonist weight-loss medication (Ozempic, Wegovy, Zepbound, etc.) for at least a month. Because of the action of this class of medication, nutrient intake is considerably less, and specific nutrient deficiencies would be expected. The goal of this study was to assess which nutrients are at most risk of being deficient. 

Nutrient intake was determined via an online questionnaire and a three-day diet diary and compared to Dietary Reference Intakes (DRI) – reference ranges developed to assess healthy intakes. 

Macronutrients: The GLP-1 users ate a higher percentage of calories from fat and consumed less than the recommended amount of fiber and protein.

Micronutrients: The GLP-1 users were deficient in the minerals calcium, magnesium, potassium, and iron; vitamins A, C, D, and E; and choline. They did, however, meet the DRI for B vitamins, zinc, copper, selenium, and phosphorus.

They did not meet the recommended number of daily servings of fruits, vegetables, grains, or dairy products. 

Note: Anticipating such deficiencies as well as potential side effects of GLP-1 weight loss medication, the Thorne Medical Affairs team wrote a Medically-Guided Weight Loss: Support Program, which includes information on how to manage side effects and fill nutrient gaps often seen during the use of these medications.

You can fill nutrient gaps with Basic Nutrients 2/Day, provide muscle support with Amino Complex or Whey Protein Isolate, offset GI side effects with probiotics, and stay hydrated with Daily Electrolytes.

Contributed by Kathi Head, ND

Reference

Exercise Timing Can Disrupt Sleep 

Exercise is widely recognized for its positive influence on sleep, metabolism, and overall well-being. But do we really know what happens when workouts are pushed into the evening hours? A new major study offers fresh insight into how the timing and intensity of evening exercise may influence sleep quality and recovery.

Using more than four million nights of biometric data from over 14,000 physically active adults, researchers examined how “exercise strain” (the combination of intensity and duration) impacts sleep when workouts occur closer to bedtime.

Key Findings:

  •  “Strain” matters: High-strain activities, such as long runs or intense training, performed within four hours of sleep were linked to delayed sleep onset, shorter sleep duration, poorer sleep quality, and changes in nocturnal heart rate and heart rate variability (HRV) – both markers of autonomic nervous system recovery.
  •  The four-hour window: Exercise that concluded at least four hours before sleep did not significantly disturb sleep, regardless of strain level. This suggests that the body needs sufficient recovery time before transitioning into restorative sleep states.
  •  Lighter workouts at night: When performed within the four-hour window before bedtime, light strain exercises, such as gentle jogs or walks, had a minimal impact on sleep quality and duration.
  •  No gender, age, or BMI differences: The study found consistent results across demographic groups, reinforcing the general applicability of the findings.

Sleep is a critical part of the recovery process, especially after strenuous activity. In this study, higher exercise strain was associated with increased resting heart rate and decreased HRV during the night, two signs that the body’s stress response remained elevated. These physiological effects can interfere with the transition into deep, restorative sleep.

To support optimal sleep quality, consider finishing intense workouts at least four hours before bedtime. If your schedule only allows for evening activity, opting for lighter, less strenuous exercise may help reduce the potential for sleep disruption.

Note: You can explore Thorne’s extensive supplement offerings for sleep support here.

Contributed by Ashley Huber, MS

Reference

Sugar-Sweetened Beverages and Sperm Health 

Consumption of sugar-sweetened beverages has increased significantly since 1990, and along with this trend, a decline in sperm health has been observed, contributing to half of the global cases of infertility. These beverages contain caloric sweeteners like sucrose, high fructose corn syrup, or fruit juice concentrate, delivering approximately 35 g of added sugar per 12 fl oz.

A key finding of the present narrative review was that regular consumption of sugar-sweetened beverages, defined as seven or more beverages per week, was correlated with a significant decline in sperm concentration and motility, compromising the ability of sperm to move toward an ovum for fertilization. They found this was primarily due to oxidative stress and hormonal disruption. 

Increased consumption of sugar-sweetened beverages has also coincided with an increased prevalence of obesity, which can disrupt sex hormone balance and alter sperm quality. Multiple studies showed an inverse relationship between intake and sperm concentration, and effects were increased in those with a higher BMI. 

Identified as one of the main contributors to altered sperm function, oxidative stress can compromise sperm function through damage to the sperm membrane, altered shape and structure of the sperm cell, and DNA damage that impairs the ability to achieve fertilization. Additionally, things like insulin resistance, caused by metabolic alterations, can exacerbate oxidative stress and hormonal imbalances brought on by increased consumption of sugar-sweetened beverages, impairing the maturation of sperm cells. Antioxidant supplementation, including vitamins C and E, glutathione, and CoQ10, has shown promise in mitigating oxidative stress.* 

Regarding hormonal disruption, high sugar-sweetened beverage intake was also linked to significantly lower serum inhibin-B levels, a marker of testicular function, which negatively regulated FSH levels, and a reduced inhibin-B/FSH ratio, which is correlated with sperm count and testicular volume. Elevated estradiol was also seen with a higher sugar-sweetened beverage intake, suggesting that these beverages disrupt male fertility via several mechanisms. 

Although more research is needed, two separate studies found that caffeinated energy drinks and sugar-sweetened beverages lowered the chance of a successful conception. It is unclear if this would have the same effect with non-caffeinated sugar-sweetened beverages. 

Overall, high sugar content in sugar-sweetened beverages can contribute to increased oxidative stress, hormonal imbalances, and metabolic dysfunctions, which can impair sperm production, male fertility, and overall reproductive health; the effects on the metabolic system may harm overall health and longevity. Sperm health is ultimately affected by the totality of lifestyle and environmental exposures, including diet, pollution, sleep, physical activity, and other modifiable factors that can affect health outcomes. The current study’s recommendations are to limit the intake of sugar-sweetened beverages because of their negative effects on sperm count, sperm motility, and increased DNA fragmentation. 

Note: Thorne’s Advanced Testosterone Support can help support healthy testosterone levels. This product contains shilajit, which has been shown to support healthy sperm number and function.* Click here to explore Thorne’s selection of nutrient and botanical antioxidants.

Contributed by Maura Donovan, MS, RD, CSSD 

Reference