Helge Einar Lundberg

• Lundberg, Helge Einar; Larsen, Stig; Mathisen, Therese Fostervold; Borgen, Tove Tveitan & Sundgot-Borgen, Jorunn (2026). Propionibacterium cheese and bone turnover in active young adults: a randomized-controlled trial. Journal of Bone and Mineral Metabolism. ISSN 0914-8779. doi: 10.1007/s00774-026-01761-9. Full text in Research Archive Show summary

  Introduction Young physically active individuals exposed to prolonged physiological stress and low energy availability are prone to reduced gonadal steroid protection and increased bone turnover. Nutritional strategies that favor positive bone remodeling balance are of clinical interest. Jarlsberg cheese contains Propionibacterium freudenreichii (PF), which produces vitamin K₂ and 1,4-dihydroxy-2-naphthoic acid (DHNA), compounds with potential favorable effects on bone health. Materials and Methods In this 24-week sex-stratified randomized-controlled trial, 60 young physically active adults engaged in endurance training were allocated to daily intake of either Jarlsberg cheese or a nutritionally comparable control cheese without PF. The primary outcome was change in serum total osteocalcin (tOC). Secondary outcomes were changes in carboxylated osteocalcin (cOC), procollagen type 1 N-terminal propeptide (P1NP), cross-linked C-terminal telopeptide of type I collagen (CTX), P1NP/CTX ratio, lumbar spine bone mineral density (BMD), and trabecular bone score (TBS). Results After 24 weeks, serum tOC was significantly higher in the Jarlsberg group than in controls (38.0 vs. 26.8 ng/mL, p < 0.01). cOC and P1NP/CTX ratio increased in favor of the Jarlsberg group (p = 0.03). Lumbar spine BMD increased in the Jarlsberg group (mean change 0.012 g/cm2, p = 0.03), with a greater increase than in controls (p = 0.05), and TBS showed a positive trend in the Jarlsberg group. Conclusion Daily intake of cheese-containing PF was associated with favorable changes in bone turnover markers and increase in lumbar spine BMD. These findings suggest that PF-fermented cheese may support bone metabolism in young individuals exposed to reduced hormonal protection and high bone turnover.

• Øistuen, Gina Flugstad; Osborne, John Owen; Sundgot-Borgen, Jorunn; Noordhof, Dionne; Taylor, Madison Y. & Heikura, Ida [Show all 16 contributors for this article] (2026). Menstrual status and bone health in athletes from different sports – a retrospective analysis. BMC sports science, medicine and rehabilitation. doi: 10.1186/s13102-026-01781-y. Full text in Research Archive Show summary

  Abstract Background Relative energy deficiency in sport (REDs) is linked to low energy availability, menstrual disturbances (MD) and low bone mineral density (BMD; Z-score < -1.0). The prevalence of these symptoms across sports and their interrelationships requires further investigation. This study aimed to 1) investigate the prevalence of severe MD and low BMD among athletes from different sports, 2) compare BMD Z-scores at lumbar spine, total hip and whole-body between regularly menstruating (RM), severe MD and hormonal contraceptive (HC) users, and 3) examine factors related to BMD among endurance athletes, including menstrual status, athletic caliber and sport-specific loading characteristics. Methods Retrospective analysis of cross-sectional data from seven projects included 411 women from 34 sports (endurance: n = 257; non-endurance: n = 154). BMD was assessed using dual-energy X-ray absorptiometry. Menstrual status was defined by the three-step method, cycle tracking or questionnaire, and categorized as RM, severe MD or HC. Endurance sports were further grouped by loading characteristics (very low, low and medium). Results Among non-HC users (51%), the prevalence of severe MD was 37% in endurance, 34% in ball sport and 36% in power- and technical- sports. BMD was not different between menstrual status groups at either lumbar spine ( P  = 0.334), total hip ( P  = 0.079) or whole-body ( P  = 0.164). Endurance athletes had lower lumbar spine BMD Z-scores than non-endurance athletes (-0.0 ± 1.0 vs 1.2 ± 1.2, P  < 0.0001), with a higher prevalence of low BMD (17% vs 2%, P  = 0.015). Total hip BMD Z-scores were lower in endurance than non-endurance athletes (0.6 ± 0.9 vs 1.4 ± 1.2, P  < 0.05 for age < 27). Among endurance athletes, neither loading characteristics nor athletic caliber were associated with BMD. However, endurance athletes with severe MD had lower total hip BMD Z-scores compared to RM athletes ( P  = 0.008) and HC users ( P  = 0.021). Conclusions The prevalence of severe MD did not differ between sport types. Overall, BMD Z-scores did not differ across menstrual status categories. However, endurance athletes had lower BMD, with total hip BMD being lower in those with severe MD. Heterogenous menstrual assessment methods across the projects included in this study may have impacted the results. Future research should integrate comprehensive REDs assessments including detailed data on menstrual status, training history, bone-loading impact and injuries in female athletes from different sports.

• Lundberg, Helge Einar; Borgen, Tove Tveitan; Kafel, Joanna; Lotfi, Sosan; Usman, Qudsia Norin & Guldal, Karina Reinfjord [Show all 10 contributors for this article] (2026). Jarlsberg cheese consumption is associated with favourable changes in bone turnover markers and BMD in postmenopausal women and older men: a randomised clinical trial. BMJ Nutrition, Prevention and Health. p. 001436–001436. doi: 10.1136/bmjnph-2025-001436. Full text in Research Archive Show summary

  Introduction Osteoporosis remains a significant global health issue, and prevention of age-related bone loss is of particular interest. Aim To assess whether daily Jarlsberg cheese fermented by Propionibacterium freudenreichii (PF) is associated with changes in bone turnover markers and bone mineral density (BMD) in postmenopausal women and men aged ≥55 years. Methods The study was performed as a randomised semi-cross-over designed multicentre trial using delayed start-up. 57 postmenopausal women and men ≥55 years, both with BMD T-score between −2.5 and 0, who did not use any osteoporosis medication were included. All participants received daily calcium and vitamin D. One group was randomly allocated to Jarlsberg from start till 32 weeks, whereas the second had a 16-week delay before Jarlsberg start-up for 32 weeks. Bone turnover markers and BMD were assessed every 16 weeks. Results In the Jarlsberg group, total osteocalcin (OC) increased from 18.8 to 23.5 ng/mL at week 32 (p<0.01), carboxylated OC from 11.8 to 17.3 ng/mL (p<0.001) and the ratio between procollagen type 1 N-terminal propeptide (P1NP) and crosslinked C-terminal telopeptide of type 1-collagen (CTX) (P1NP/CTX) from 168.8 to 203.9 (p<0.01). Lumbar spine BMD increased from 1.151 to 1.163 g/cm² (p=0.04) and total hip BMD from 0.929 to 0.933 g/cm² (p=0.02). The differences between groups in BTM were significant in favour of Jarlsberg cheese. After Jarlsberg was introduced, OC-level, biomarkers and BMD increased. Conclusion Jarlsberg intake alongside calcium and vitamin D was associated with favourable increases in OC-related markers, P1NP/CTX ratio and BMD in postmenopausal women and older men.

• Lundberg, Helge Einar; Larsen, Stig; Sundgot-Borgen, Jorunn & Mathisen, Therese Fostervold (2026). Seasonal changes in energy intake and emerging indicators of energy availability in young elite Nordic skiers. Journal of the International Society of Sports Nutrition (JISSN). 23(1). doi: 10.1080/15502783.2026.2634184. Full text in Research Archive Show summary

  Background Nordic skiing, an energy-demanding endurance sport, may be particularly susceptible to low energy availability (LEA) and relative energy deficiency in sport (REDs). The objective was to examine the nutritional practices and physical symptoms associated with (REDs among young elite Norwegian Nordic skiers during the off-season, with particular emphasis on energy and CHO intake, in the transition from the competitive season to preparation for the subsequent season. Methods Thirty female and thirty male Nordic skiers participated in a 24-week controlled clinical trial. The daily dietary intake variables were carbohydrates (CHO), protein, and calcium (Ca) intake and weekly training hours. The blood variables were vitamin D, total osteocalcin (tOC), procollagen type 1 N-terminal propeptide/cross-linked C-telopeptide type 1-collagen (PINP1/CTX1) ratio, heart rate (HR), resting metabolic rate (RMR), bone mineral density (BMD), lean body mass (LM), visceral adipose tissue (VAT), and body fat percentage (BF%). Results Energy intake increased by 25%, and CHO increased by 14.5% for both sexes during the study, and training volume increased by 41% for female athletes and 83% for male athletes, respectively. There were positive correlations between higher BMD, bone markers, RMR, and LM and negative correlations between VAT and REDs symptoms. VAT was correlated with RMR and bone markers. LM emerged as a key predictor for health variables, explaining variability across multiple REDs markers. Conclusions Nordic skiers seem unable to increase energy intake sufficiently during the preparation period, leading up to the competitive season, as demonstrated by a large discrepancy between changes in energy intake, especially CHO, and exercise volume. The correlations between energy intake and BMD, RMR, VAT, and HR underscore the clinical consequences of insufficient energy intake, which may arise if individuals focus on low body mass and body fat percentage without sufficient knowledge. VAT, tOC, and the P1NP/CTX-ratio are promising indicators for monitoring dietary interventions in individuals with REDs and should be considered in future research on REDs treatment strategies.

• Lundberg, Helge Einar; Kafel, Joanna; Holo, Helge & Larsen, Stig (2025). Daily cheese intake positively affects serum osteocalcin levels, vitamin K status and bone turnover markers in elderly men and women. BMJ Nutrition, Prevention and Health. 8(2), p. 494–502. doi: 10.1136/bmjnph-2024-000933. Full text in Research Archive
• Mathisen, Therese Fostervold; Sundgot-Borgen, Jorunn; Macnaughton, Lindsay; Rustaden, Anne Mette; Løkkevik, Inger Johanne & Lundberg, Helge Einar [Show all 7 contributors for this article] (2025). Knowledge of low energy availability in biathlon: Why coaches need more targeted education. Results from a national, cross-sectional study. International journal of sports science & coaching. ISSN 1747-9541. doi: 10.1177/17479541251407845. Full text in Research Archive Show summary

  This study explores the knowledge of coaches working with adolescent biathletes regarding eating disorders (ED), low energy availability (LEA), and Relative Energy Deficiency in Sport (REDs). METHODS: Recruited coaches completed a questionnaire assessing self-reported knowledge (scale 0–10) of ED, LEA and REDs, and secondly by articulating their knowledge (scored by three experts, scale 0–2). RESULTS: Thirty-three coaches participated (mean age 40.6 ± 12.2 years), most without formal coach education (n = 25, 75.8%), and 13 (39.4%) were female. Self-reported knowledge of LEA/REDs was lower than ED knowledge (4.75 ± 2.9 vs. 5.74 ± 2.5; p = 0.02, g = 0.4), with a similar pattern in expert-rated scores (0.72 ± 0.6 vs. 1.12 ± 0.6; p < 0.01, g = 0.8). A regression model explained 45% of variance in self-reported LEA/REDs knowledge, with education level and course participation positively associated, while sex had no significant effect. For expert-rated scores, the model explained 33% of variance, with only course participation significant. For knowledge of guidelines on addressing LEA/REDs concerns self-reported scores were 3.6 ± 2.9, and 4.5 ± 2.9 for ED concerns (p = 0.04, g = 0.4); and expert-assessed scores were 0.7 ± 0.7 and 0.9 ± 0.8 (p = 0.11), respectively. Regression models did not significantly explain variability in these scores CONCLUSION: Biathlon coaches are less aware of LEA/REDs symptoms and less confident in addressing them than symptoms of ED. Importantly, education and course attendance raised knowledge scores, and preferred learning methods were virtual or physical courses with experts over scientific papers.

• Lundberg, Helge Einar; Larsen, Stig; Mathisen, Therese Fostervold & Sundgot-Borgen, Jorunn (2025). Comparison of cheese with and without Propionibacterium freudenreichii subsp. shermanii LMGT 2951 on off-season muscle strength and VO2 max development in Nordic skiers: a randomized clinical trial. Journal of the International Society of Sports Nutrition (JISSN). 22(1). doi: 10.1080/15502783.2025.2566373. Full text in Research Archive Show summary

  Background and objective: Nordic skiers represent a low-impact, weight-sensitive sport and may be inclined to engage in weight-controlling behavior, hence increasing their risk for low energy availability and impairment in health and performance. Jarlsberg cheese (J) is rich in vitamin K₂ from fermentation by Propionibacterium freudenreichii subsp. shermanii LMGT 2951 (Pf) and lactic acid bacteria and increases the osteocalcin (OC) level. Vitamin K is essential for activating OC, which is described to be associated positively with muscle strength, whereas propionic acid bacteria are found to enhance endurance. Except for Pf and its by-products, J and Norvegia (N) cheeses have almost identical nutrient content. The objective of this study was to compare the effects of Jarlsberg and N as potential supplements to training on muscle strength (MS), lean body mass (LBM) and VO2 max. Methods: Thirty female and 30 male Nordic skiers were block randomized 1:1 to either J or N and studied during a 24-week offseason training schedule. The Norvegia group served as a control group. Females and males were treated with 75 and 90 grams/day, respectively. MS by seated pulldown and half-squat, LBM by DXA, and VO2 max were measured at baseline and after the 24 weeks off-season period. Dietary intake and training hours were registered and monitored at baseline and every eight weeks during the study. Results: MS significantly increased in both groups after 24 weeks (p < 0.01). The mean increase difference in MS-upper body favored Jarlsberg by 0.95 kg (95% CI: −0.02–1.46), approaching significance (p = 0.06). No significant difference was found between groups in MS-lower body. LBM and VO2-max both increased significantly in each group (p ≤ 0.05), with no notable differences between groups. Correlation analysis identified LBM as the dominant outcome variable at both baseline and 24 weeks. Endurance training was the dominant input variable and correlated significantly positively both multiply and partially to LBM, (p = 0.04, p = 0.02), respectively. At baseline and 24-weeks sex, endurance training along with OC-level explained 65% and 68% of the LBM variations, respectively. Conclusion: Both Jarlsberg cheese, characterized by its unique Propionibacterium freudenreichii content, and Norvegia cheese, when combined with off-season training, led to increases in LBM, VO₂ max, and MS, with no significant differences observed between groups. However, there was a trend toward greater improvements in MS in the Jarlsberg group. Overall, increases in LBM through structured training appear to be a key driver of gains in both muscle strength and aerobic capacity.

• Lundberg, Helge Einar; Sundgot-Borgen, Jorunn; Mathisen, Therese Fostervold; Holo, Helge; Whist, Anne Cathrine & Larsen, Stig (2024). Cheese positively affects serum osteocalcin levels, bone turnover markers and bone mineral density in cross-country skiers: a dose-response study. International Journal of Clinical Trials (IJCT). ISSN 2349-3240. 11(2). doi: 10.18203/2349-3259.ijct20240961. Full text in Research Archive

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