Loading muscle and bone in the window

What changes for muscle and bone

Women face a different musculoskeletal picture than men across midlife. Oestrogen has a moderating effect on bone turnover and on muscle protein synthesis; as oestrogen becomes more variable through the perimenopause window, that moderation weakens. Iron demand patterns also shift with cycle changes, and most of the research the mainstream sports-supplement conversation cites was conducted on male subjects in their twenties — which does not necessarily generalise. [3]

Three gaps define the supplement conversation for active women in this window. The iron situation: lower iron status is meaningfully more common in active women than active men at the same training volume. The post-training wellbeing question: EPA/DHA, protein timing, and the maintenance of normal muscle function weigh differently for women in midlife than for younger male athletes. And the creatine gap: creatine is one of the three ingredients with the most evidence for use in females per the ISSN 2023 position stand, and it is consistently under-represented in women’s routines — including in Solgar UK’s catalogue. [5]

The active-woman foundation reads bisglycinate iron when ferritin testing supports it, TG-form omega-3 at the heart-claim dose, and a women-targeted multivitamin as the daily-cover layer. Iron contributes to normal oxygen transport in the body and to the reduction of tiredness and fatigue, which is why the cluster anchors on bisglycinate at the 20 mg per-capsule dose tier rather than ferrous sulfate at higher elemental doses. We describe iron as a confirmed-low-status supplement only — ferritin first, dose second; the bisglycinate form is the right starting point because it tolerates the elemental dose tiers used across the trial literature. For women applying training stress through the perimenopausal window, supplementation supports the dietary pattern, never replaces it; the cluster sequences iron, omega-3, and a foundation multi behind the eating shape.

What the research examines

Two ingredient categories carry GB-authorised health claims directly relevant to loading muscle and bone in the window: iron (red blood cells, haemoglobin, oxygen transport, reduction of tiredness and fatigue) and EPA/DHA (heart function at ≥250 mg/day, with broader cardiovascular research at higher doses). [1] Two more sit in research-context only: creatine (no UK authorised claim, named as a top-evidence ingredient for active females by ISSN 2023, not stocked by Solgar UK) and BCAAs / L-glutamine (moderate-evidence tier; we name them, we do not card them).

Research findings

1. Lower iron status is meaningfully more common in active women than active men at the same training volume.

   Sim et al.’s 2019 narrative review reports prevalence of approximately 15–35% in female athlete cohorts versus 5–11% in male athlete cohorts. The test-first principle is standard: ferritin before supplementation, then retest at three months. Iron carries authorised claims for normal formation of red blood cells and haemoglobin, normal oxygen transport, and reduction of tiredness and fatigue — exactly the outcomes that compound through midlife when iron status drifts low.

   Source: Sim 2019 + EU 432/2012 · Narrative review + GB-authorised claims

2. Iron bisglycinate is non-inferior to ferrous sulfate at lower elemental doses, with better digestive tolerance.

   Milman et al.’s 2014 head-to-head trial in pregnant women found 25 mg bisglycinate non-inferior to 50 mg ferrous sulfate for prophylaxis of iron deficiency, with better tolerability. The defensible framing is non-inferior at lower dose with better tolerability — not the popular ‘2× bioavailability’ figure, which is not robustly established by head-to-head human RCTs.

   Source: Milman 2014 RCT · Pregnancy prophylaxis, head-to-head

3. Creatine is named as one of the top three ingredients with the most evidence in active females — and Solgar UK does not stock it.

   The ISSN 2023 female-athlete position stand identifies caffeine, iron, and creatine as the ingredients with the most evidence for use in females. Standard maintenance dose is 3–5 g/day (Kreider 2017 ISSN position stand). Smith-Ryan 2021 and 2025 cover creatine across the lifespan and through the menopausal transition. Bone-relevant outcomes are mixed at the meta-analytic level (Chilibeck 2015 femoral-neck positive; Forbes 2018 null aggregate). Creatine has no UK authorised health claim and is not in the Solgar UK catalogue — flagged as a gap rather than substituted.

   Source: Sims 2023 + Smith-Ryan 2021/2025 · ISSN position + reviews

4. BCAAs and L-glutamine sit in the moderate-evidence tier — useful to name, not to overstate.

   The ISSN 2023 female-athlete position stand explicitly does not place BCAAs or L-glutamine in the top-evidence tier. Both can be appropriate when dietary protein intake is irregular or during high-volume training phases, but neither carries a UK authorised health claim and the trial base is moderate rather than strong. We name them; we do not card them.

   Source: Sims 2023 ISSN position stand · No UK authorised claims

Evidence at a glance

Reader questions

Do women in midlife need creatine?

The research base in women — including women through the menopausal transition and beyond — has expanded significantly. The ISSN 2023 female-athlete position stand identifies creatine as one of the three ingredients with the most evidence for use in females. Standard maintenance dose is 3–5 g per day. Concerns about water retention or ‘bulking’ are not supported by trial data at that dose. Solgar UK does not currently stock creatine; we flag this as a catalogue gap rather than substitute another brand we have not evaluated against the same three criteria.

Should I take BCAAs?

If dietary protein intake is adequate (roughly 1.6–2.0 g per kg bodyweight for active women), BCAAs are optional rather than essential. They become more useful when protein intake is irregular or during high-volume training phases. The ISSN 2023 position stand does not place BCAAs in the top-evidence tier for active females. We do not card BCAAs as a primary recommendation.

When should I supplement iron?

After a ferritin test, not before. Routine iron supplementation without testing can be counter-productive — for women whose iron status is already in range, supplementation does not produce the outcomes the trials describe and can cause digestive issues. The standard pattern: test ferritin, supplement if low, retest at three months, adjust. The NHS iron-deficiency-anaemia pathway is the right starting point.

What about protein powder?

Outside our scope on this page — food first, then a whole-food protein (whey or pea) if convenient. The supplement decisions that map most directly to the research for active women in midlife are iron, EPA/DHA, creatine, and a foundation multivitamin — in roughly that order.

Do I need to be in a gym for this to apply?

No. The page is written for any woman in the perimenopause window who is loading muscle and bone — resistance, impact, weight-bearing — at any volume. The iron and EPA/DHA cases scale across activity levels; the creatine case applies most cleanly when resistance loading is part of the routine. Walking and bodyweight work count as loading.

Why Solgar specifically? Are you the Solgar site?

We are not. HerStack is published by Suggestic, a digital nutrition company. We picked Solgar UK as the reference brand for three reasons set out in our formulation criteria: bioavailable forms across most of the range, transparent dosing on the labels, and third-party testing on the supplements we recommend. Where Solgar’s formulation does not meet our criteria, we say so on the page and link to alternatives.

Recommendations: three reference picks with formulation reasoning

Each entry carries the form chosen, the rationale, the authorised claim text, and the Amazon.co.uk link. Affiliate disclosure: HerStack is a participant in the Amazon EU Associates Programme.

1. Solgar Gentle Iron (Iron Bisglycinate) 20 mg Vegetable Capsules

   Form: Iron · Bisglycinate (gentle)

   Rationale: Bisglycinate form for digestive tolerance. Milman 2014's head-to-head trial found bisglycinate non-inferior to ferrous sulfate at lower elemental dose, with better tolerability — the right form for a reader who will be supplementing daily across months. The 20 mg dose is appropriate when ferritin testing has confirmed low iron status. Do not supplement iron blind.

   Authorised claim: Iron contributes to the normal formation of red blood cells and haemoglobin, to normal oxygen transport in the body, and to the reduction of tiredness and fatigue.

   Price: £16.10 · Tag: Reference pick

   Link: https://www.amazon.co.uk/dp/B00068X4IG?tag=herstack-21

2. Solgar Triple Strength Omega-3 Softgels

   Form: Omega-3 · TG-form, third-party tested

   Rationale: EPA and DHA at the dose threshold for the GB-authorised heart-function claim. Triglyceride form is more bioavailable than ethyl esters at the same total EPA/DHA. Same SKU we recommend on the longevity cluster — the nutrient case overlaps when a woman is loading the cardiovascular system regularly.

   Authorised claim: EPA and DHA contribute to the normal function of the heart, with a daily intake of 250 mg.

   Price: £38.85 · Tag: Reference pick

   Link: https://www.amazon.co.uk/dp/B000NI6WHY?tag=herstack-21

3. Solgar Female Multiple Multivitamin Tablets

   Form: Multivitamin · Women-specific foundation

   Rationale: A women-targeted multivitamin covering the nutrient gaps most common in active women's diets. Authorised claims apply across the formulation: B vitamins for normal psychological function and the reduction of tiredness and fatigue; vitamin D and magnesium for the maintenance of normal muscle function and bones; iron (when included at appropriate dose) for the same red-blood-cell and oxygen-transport claims as the Gentle Iron SKU.

   Authorised claim: Multiple GB-authorised claims apply to individual nutrients in the formulation. Read the current Solgar UK label for exact dosing per nutrient.

   Price: £22.50 · Tag: Reference pick

   Link: https://www.amazon.co.uk/dp/B00028Q6G2?tag=herstack-21

Not recommended on this page: creatine monohydrate. The ISSN 2023 female-athlete position stand identifies creatine as one of the three ingredients with the most evidence for use in females; standard maintenance dose is 3-5 g/day. Solgar UK does not currently stock creatine; we flag this as a catalogue gap rather than substitute another brand we have not evaluated against the same three criteria. BCAAs and L-glutamine sit in the moderate-evidence tier and are not carded as primary recommendations. See gap policy at herstack.co.uk/about.

What to look for in a brand: three criteria

1. Iron form on the label. Bisglycinate is not ferrous sulfate. Bisglycinate costs more, absorbs comparably at lower elemental dose, and is better tolerated — particularly for women supplementing consistently over months. The label should disclose the iron form, not just “iron 20 mg”.
2. Banned-substance certification. For competing athletes, look for Informed Sport or equivalent third-party certification on every batch. Less critical for recreational training, essential at competitive level. Iron and omega-3 are unlikely to trigger a positive test; multivitamins occasionally do.
3. Omega-3 oxidation testing. Fish-oil preparations can oxidise on the shelf; oxidised oil is worse than no oil at all for cardiovascular and post-training outcomes. Brands testing for peroxide value and anisidine value, and publishing the results, are doing meaningful quality work.

Citations

1. GB Nutrition & Health Claims register / Commission Regulation (EU) No 432/2012 (retained). Iron — contribution to normal formation of red blood cells and haemoglobin, normal oxygen transport, and reduction of tiredness and fatigue. gov.uk/health-claims
2. GB Nutrition & Health Claims register / Commission Regulation (EU) No 432/2012 (retained). EPA and DHA — contribution to the normal function of the heart at ≥250 mg/day. gov.uk/health-claims
3. Sim M, Garvican-Lewis LA, Cox GR, Govus A, McKay AKA, Stellingwerff T, Peeling P. Iron considerations for the athlete: a narrative review. European Journal of Applied Physiology, 2019;119(7):1463-1478. (Reports 15–35% prevalence of lower iron status in female athlete cohorts vs 5–11% in male.) PMID 31055680
4. Milman N, Jønsson L, Dyre P, Pedersen PL, Larsen LG. Ferrous bisglycinate 25 mg iron is as effective as ferrous sulfate 50 mg iron in the prophylaxis of iron deficiency and anemia during pregnancy in a randomized trial. Journal of Perinatal Medicine, 2014;42(2):197-206. (Bisglycinate non-inferior at half the elemental dose, better tolerated.) PMID 24152889
5. Sims ST, Kerksick CM, Smith-Ryan AE et al. International Society of Sports Nutrition position stand: nutritional concerns of the female athlete. Journal of the International Society of Sports Nutrition, 2023;20(1):2204066. (Caffeine, iron, and creatine identified as the ingredients with the most evidence for use in females.) PMID 37221858
6. Hu Y, Hu FB, Manson JE. Marine omega-3 supplementation and cardiovascular disease — an updated meta-analysis of 13 randomized controlled trials involving 127,477 participants. Journal of the American Heart Association, 2019;8(19):e013543. DOI 10.1161/JAHA.119.013543
7. Smith-Ryan AE, Cabre HE, Eckerson JM, Candow DG. Creatine supplementation in women's health: a lifespan perspective. Nutrients, 2021;13(3):877. PMID 33800439
8. Smith-Ryan AE, DelBiondo GM, Brown AF, Kleiner SM, Tran NT, Ellery SJ. Creatine in women's health: bridging the gap from menstruation through pregnancy to menopause. Journal of the International Society of Sports Nutrition, 2025;22(1):2502094. PMID 40371844
9. Kreider RB, Kalman DS, Antonio J et al. International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation in exercise, sport, and medicine. Journal of the International Society of Sports Nutrition, 2017;14:18. PMID 28615996
10. Chilibeck PD, Candow DG, Landeryou T, Kaviani M, Paus-Jenssen L. Effects of creatine and resistance training on bone health in postmenopausal women. Medicine & Science in Sports & Exercise, 2015;47(8):1587-95. PMID 25386713
11. Forbes SC, Chilibeck PD, Candow DG. Creatine supplementation during resistance training does not lead to greater bone mineral density in older humans: a brief meta-analysis. Frontiers in Nutrition, 2018;5:27. PMID 29740583
12. NHS. Iron deficiency anaemia — diagnosis and pathway. National Health Service, retained 2025. nhs.uk/conditions/iron-deficiency-anaemia