A groundbreaking study from Dalhousie University has uncovered a surprising twist in the world of fitness supplements and exercise. Researchers found that sodium nitrate, a common ingredient in popular workout products like beetroot juice concentrates and nitrate powders, may hinder the heart's beneficial adaptations to aerobic exercise in females. This discovery challenges long-held assumptions about these supplements enhancing cardiovascular performance, particularly for women who are increasingly turning to fitness routines to safeguard their heart health.

The research, published in Scientific Reports on May 3, 2026, highlights significant sex differences in how the body responds to nitrates combined with physical activity. While exercise alone promotes positive changes in heart structure and function, adding sodium nitrate appears to blunt these effects in female mice, with minimal impact on males. Led by Dr. Susan Howlett from Dalhousie’s Department of Pharmacology, the study underscores the need for gender-specific research in sports nutrition, an area often dominated by male-focused trials.

The Rise of Nitrate Supplements in Canadian Fitness Culture

Sodium nitrate supplements have surged in popularity across Canada, fueled by marketing claims of improved endurance, oxygen efficiency, and cardiovascular support. Found naturally in beetroot and leafy greens, concentrated forms are staples in pre-workout routines for runners, cyclists, and gym-goers. Survey data indicates over 40 percent of Canadians use dietary supplements, with nitrate-rich products like beetroot juice gaining traction among active adults seeking performance edges.

In Canada, where physical activity levels are rising—with women comprising a growing segment of fitness participants—these supplements promise to amplify exercise benefits. Heart disease remains the leading cause of death for Canadian women, with 90 percent at risk due to factors like hypertension, inactivity, and poor diet, according to the Heart and Stroke Foundation. Regular aerobic exercise is a proven protector, reducing cardiovascular event risks by up to 30 percent for women, yet supplement interactions remain understudied.

Dalhousie’s investigation arrives at a pivotal moment, as women’s wellness products, including fitness supplements, drive a market projected to reach CAD 13.9 billion by 2033. This research from a leading Canadian institution prompts fitness enthusiasts to reconsider untested combos.

Unpacking the Dalhousie Study Methodology

The study utilized a controlled experiment with 7- to 9-month-old male and female mice, equivalent to middle-aged humans. Animals were divided into four groups: sedentary controls, nitrate-supplemented (1 mM sodium nitrate in drinking water), exercise-only (voluntary running wheel access), and combined nitrate plus exercise for 12 weeks. This duration mimics chronic supplement use alongside regular aerobic training.

Researchers assessed heart structure and function via echocardiography, measuring parameters like heart mass, wall thickness, and global longitudinal strain—a key indicator of ventricular performance. At the cellular level, they isolated ventricular myocytes to evaluate contraction, relaxation, and calcium transients, which govern heartbeat rhythm. Myofilament function, including Mg-ATPase activity crucial for muscle relaxation, was tested in ventricular tissue. Calcium handling genes were also analyzed for molecular insights.

This rigorous, sex-stratified approach addresses a critical gap: most prior nitrate studies focused solely on males, overlooking physiological differences between sexes in cardiac responses to exercise and supplements.

Key Findings: Blunted Benefits in Female Hearts

In female mice, running alone delivered clear cardiovascular gains. Hearts grew heavier with thicker walls, signaling adaptive hypertrophy that enhances pumping efficiency. Myocyte contraction and relaxation accelerated, driven by faster calcium transients. At higher calcium levels, Mg-ATPase activity dropped, optimizing relaxation under stress.

Sodium nitrate alone had no effect. However, when paired with running, it negated these adaptations: global longitudinal strain worsened, indicating impaired ventricular function; contraction and relaxation speeds failed to improve; and Mg-ATPase changes were blocked. Remarkably, after a two-week nitrate washout, exercise benefits reemerged, suggesting reversible interference.

“We expected nitrates and exercise to work together to improve heart health. Instead, in females, the supplement prevented many of the positive cardiac adaptations normally produced by exercise,” said Dr. Howlett. This points to nitrates disrupting calcium handling and myofilament sensitivity, potentially via nitric oxide pathways that differ by sex.

Sex Differences: Why Females Respond Differently

Male mice ran less than females, yet nitrates showed minimal impact. No changes in myocytes from nitrates alone or combined; only slight prolongation of isovolumic relaxation time with exercise plus nitrates. Calcium handling genes and Mg-ATPase remained largely unaffected at physiological levels.

These disparities align with Dalhousie’s Heart Health Lab focus on sex-specific cardiac aging. Females exhibit unique estrogen-modulated calcium dynamics, which decline post-menopause, elevating heart disease risk. Exercise typically counters this via structural and functional remodeling, but nitrates may override these protective mechanisms in females through excessive nitric oxide signaling, impairing adaptation.

Such findings echo broader Canadian research emphasizing sex as a biological variable. The Heart and Stroke Foundation notes women’s heart disease often presents differently, with underdiagnosis contributing to higher post-event mortality.

Photo by Aniket Ganguly on Unsplash

Meet the Researchers Behind the Discovery

Dr. Susan E. Howlett, Professor of Pharmacology and Medicine at Dalhousie, leads the Heart Health Lab. Her work explores age, frailty, and sex hormones’ roles in heart disease, funded by the Heart and Stroke Foundation. Recent awards include the University Research Professorship and Legacy Awards for graduate supervision. Co-authors Elise S. Bisset (now postdoc at Université de Montréal), Gracious D. S. Kasheke, Scott A. Grandy (Dalhousie Health and Human Performance), and W. Glen Pyle (BC Women’s Hospital) contributed expertise in cardiac physiology and myofilament function.

The lab’s mouse models mimic human aging, providing translational insights into testosterone deficiency, estrogen loss, and frailty’s cardiac toll—critical as Canadian women over 50 face rising heart risks.

Implications for Canadian Women in Fitness

For the millions of Canadian women hitting the gym or trails, this study urges caution with nitrate supplements. While touted for vasodilation and endurance, they may compromise exercise’s cardioprotective remodeling, especially long-term. Read the full Scientific Reports paper for technical details.

Heart disease claims a woman’s life every 20 minutes in Canada; exercise slashes risks, but interactions matter. Fitness apps and influencers promote beetroot shots, yet sex-specific data is scarce. Consult professionals before stacking supplements with workouts.

From Mice to Humans: The Need for Clinical Trials

While compelling, mouse findings require human validation. Dalhousie calls for female-inclusive trials on chronic nitrate use with aerobic exercise. Ongoing Canadian efforts, like the Women@Heart NS pilot and CIHR-funded networks, prioritize women’s cardiovascular research. For details, see Dalhousie’s news release.

Health Canada regulates supplements as natural health products, but efficacy claims lag. This study bolsters calls for evidence-based labeling, protecting active women.

Dalhousie’s Role in Advancing Women’s Heart Research

Dalhousie exemplifies Canadian higher education’s strength in biomedical research. The Heart Health Lab’s sex-focused approach addresses gaps: women’s trials comprise under 30 percent of cardiac studies. Funded by Heart and Stroke (Grant G-22-0031992), this work influences policy and inspires peers like McGill and UBC.

With 2.6 million Canadians living with heart disease, university labs drive innovation, from frailty indices to hormone therapies.

Broader Impacts and Future Directions

This research spotlights overlooked sex differences, urging personalized nutrition. Future studies may test doses, durations, and human cohorts. For women, prioritize whole foods, balanced training, and medical advice over hype.

Explore Dalhousie’s Heart Health Lab for ongoing work on estrogen, testosterone, and frailty.

Photo by Sahil Babbar on Unsplash

Actionable Insights for Heart-Healthy Fitness

• Focus on consistent aerobic exercise without unproven add-ons for proven heart gains.
• Women: Monitor symptoms; consult cardiologists on supplements.
• Support sex-inclusive research via Canadian unis like Dalhousie.
• Track progress with wearables, prioritizing recovery and nutrition.

Dalhousie’s findings empower informed choices, advancing women’s cardiac wellness through rigorous science.