Micronutrients & Electrolytes
Research on micronutrients and electrolytes for active people — calcium, magnesium, vitamin C, B vitamins, and daily reference intakes (DRIs).
Micronutrients Relevant to Exercise
Micronutrients & Electrolytes
Does taking iron improve your workouts if you're low?
About this study
Studies pooled
24 trials
Women of reproductive age, most trials in iron-deficient or anemic women. Researchers pooled randomized trials giving daily iron versus placebo and measured aerobic capacity and exercise heart rate.
The finding
Giving iron to women who are low on it improves how much oxygen their body can use during hard exercise, and lets them work at a lower heart rate for the same effort. The gain is concentrated in women who start out iron-deficient or anemic — it is not a boost for women whose iron is already normal.
The answer
+2.35 mL/kg/min VO₂max
Also: exercise heart rate about 4 bpm lower. Biggest gains in anemic or iron-deficient women.
If you're a woman who trains and runs low on iron — heavy periods, a low-meat diet, or a diagnosed deficiency are the usual causes — correcting it can measurably raise your aerobic capacity and make a given effort feel easier. If your iron is already normal, extra iron won't boost performance and can be harmful, so test before you supplement.
Micronutrients & Electrolytes
Can extra vitamin D make you a better athlete?
About this study
Type
Mechanism review
A review of vitamin D biology in athletes. Vitamin D receptors are found in skeletal muscle, and the authors build a mechanistic case for higher status — but no long-term trials test the performance claims directly.
The finding
Vitamin D does more than protect bone — its receptors sit inside muscle, where it may influence strength and recovery. From that biology, the authors argue athletes might benefit from keeping levels at the high end of normal. It's a plausible idea built on mechanism, not proven by outcome trials.
The answer
Maybe
Proposed by the authors: keep 25(OH)D near 100 nmol/L; suggested 4,000–5,000 IU/day with vitamin K. Unproven for performance.
Fixing a real vitamin D deficiency reliably helps how your muscles work; pushing an already-normal level higher to chase extra performance is unproven. If you train indoors, live somewhere with long winters, or have darker skin, it's worth testing your level. Very high doses aren't automatically better and carry their own risks, so supplement to correct a shortfall, not to megadose.
Micronutrients & Electrolytes
Do magnesium and vitamin D help you perform better?
About this study
Type
Narrative review
A review pulling together what's known about magnesium and vitamin D in active people. Both are cofactors in energy metabolism and muscle function; athletes often run low on both, and no trial has tested taking them together.
The finding
Magnesium and vitamin D both matter for how muscles contract and how the body turns food into usable energy, and active people are more likely to fall short on them. The review finds hints that topping up either one can help performance or recovery — but the signal is soft, and no one has tested the combination.
The answer
Only if you're low
Neither magnesium nor vitamin D is a proven performance booster on its own. Where they help is by fixing a shortfall — and both are common shortfalls in people who train hard, diet, or sweat a lot. Aim to get enough through food and correct a measured deficiency; don't expect a supplement stack to add performance if your levels are already fine.
Micronutrients & Electrolytes
Does magnesium raise testosterone in men?
About this study
Type
Narrative review
Older men are the focus. The authors synthesize observational data plus a handful of small trials on magnesium and anabolic hormones — no large randomized trial exists.
The finding
In men, higher magnesium levels line up with higher active testosterone, and a few small studies suggest supplementing may nudge it upward — especially when paired with exercise. The relationship is mostly correlational, and the authors are upfront that it needs bigger trials before anyone banks on it.
The answer
A modest link
Largest in older or deficient men; strongest for bioavailable (non-SHBG-bound) testosterone.
If your magnesium is low, correcting it may modestly support your testosterone — but magnesium is not a testosterone booster for men who already get enough. The evidence is mostly observational, so treat it as one more reason to hit your magnesium target through food, not as a hormone hack. The men most likely to notice are older, deficient, or training hard.
Micronutrients & Electrolytes
Does vitamin D improve elite athletes' strength and endurance?
About this study
Studies reviewed
14 trials
People
482 athletes
Elite athletes across sports. Reviewers gathered randomized, placebo-controlled trials of vitamin D supplementation and counted how many showed benefits for aerobic capacity, anaerobic power, strength, and bone/inflammatory markers — a systematic review, not a statistical meta-analysis.
The finding
Across trials in elite athletes, vitamin D helped most where power and strength were measured — the majority of those studies showed a benefit. Aerobic and sprint measures moved less consistently. As with most vitamin D research, the athletes who gained were generally those starting from low levels.
The answer
Yes — mostly strength
Anaerobic power/strength: improved in 5 of 7 trials. Aerobic capacity: 2 trials improved. Sprint speed: no change in most.
If you compete or train seriously and your vitamin D is low, correcting it is most likely to show up in strength and power work. Don't expect a big endurance or sprint boost, and don't megadose — the benefit comes from reaching adequacy, not from stacking high doses. Test in winter or if you train mostly indoors.
Micronutrient Reference Values (DRIs)
The reference values shown for the 20 micronutrients we track are Dietary Reference Intakes (DRIs), developed by expert committees of the U.S. National Academies of Sciences, Engineering, and Medicine (formerly the Institute of Medicine). DRIs are the consensus reference values used in U.S. and Canadian nutrition policy.
- RDA (Recommended Dietary Allowance) — meets the needs of ≥97.5% of healthy individuals in a life-stage group.
- AI (Adequate Intake) — used when evidence is insufficient to set an RDA. Treated as a goal in the same way.
- UL (Tolerable Upper Intake Level) — the highest daily intake unlikely to cause adverse effects in apparently healthy people. For some nutrients (niacin, folate, magnesium, vitamin E, vitamin A retinol), the IOM UL applies only to supplemental or pharmacological sources, not to nutrients from whole foods. Where this is the case we do not display a UL warning, since this app tracks total dietary intake.
- CDRR (Chronic Disease Risk Reduction Intake) — used for sodium only; the level above which intake increases chronic disease risk.
Reference values vary by age and sex; individual needs may differ. Pregnancy, lactation, and certain medical conditions are not currently modeled. Consult a healthcare provider for personalized guidance.
Calcium — Bone Health & Muscle Function
Micronutrients & Electrolytes
Does more calcium meaningfully strengthen your bones?
About this study
Studies pooled
59 RCTs
BMD change
0.7–1.8 %
Adults over 50. Reviewers pooled 15 trials of dietary calcium and 51 of calcium supplements, measuring bone mineral density at one and two years.
The finding
Boosting calcium — from food or pills — nudges bone density up by about one to two percent, and then it stops. Because the gain is small and doesn't keep building over time, it's unlikely on its own to cut your risk of breaking a bone.
The answer
1–2% bone density (then plateaus)
Same small effect from food or supplements. Not enough, alone, to lower fracture risk.
Getting enough calcium matters, but going above adequate intake buys you only a one-time ~1–2% bump in bone density that won't keep your bones getting stronger. For fracture prevention, calcium works as part of a package — paired with vitamin D and, above all, weight-bearing exercise — not as a standalone lever. Hit your target and don't bother megadosing.
Micronutrients & Electrolytes
Do calcium and vitamin D together prevent fractures?
About this study
Studies pooled
8 RCTs
People
30,970 adults
Middle-aged and older adults, both community-dwelling and in care. Trials gave calcium and vitamin D together — not calcium alone — and tracked fractures.
The finding
When calcium and vitamin D are taken together, older adults break fewer bones — total fractures dropped about 15% and hip fractures, the most serious kind, about 30%. The pairing matters: calcium on its own (previous card) barely moves fracture risk.
The answer
−30% hip fractures (with vitamin D)
Total fractures −15% · Hip fractures −30%. Effect is for the calcium + vitamin D combination, not calcium alone.
If bone health is your concern — especially as you age — the evidence-backed move is calcium and vitamin D together, not either one solo. Reaching your daily target for both meaningfully lowers fracture risk. This is why the app tracks the two side by side rather than treating calcium as a standalone bone nutrient.
Micronutrients & Electrolytes
Does eating more calcium make you stronger?
About this study
People
95 athletes
Age range
18–30 years
Young athletes across several sports, measured once in a lab. Researchers compared self-reported calcium intake against muscle-performance tests — a snapshot, not a supplementation trial.
The finding
Athletes who ate more calcium tended to score a bit higher on muscle tests like push-ups, but the link was weak and calcium explained only a small slice of the differences between people. This is an association in a one-time snapshot, not proof that adding calcium makes you stronger.
The answer
A weak link
Push-ups vs calcium intake: r = 0.28. Most of the performance difference came from other factors.
Calcium is essential for muscle contraction, but eating extra beyond adequacy won't reliably make you stronger — this snapshot found only a faint correlation, and correlation in a single-timepoint study can't show cause. Cover your calcium target for bone and general health; look to training and protein for strength gains.
Potassium & Sodium — Electrolytes, Blood Pressure & Exercise
Micronutrients & Electrolytes
Does eating more potassium lower your blood pressure?
About this study
RCTs pooled
22 trials
Cohort adults
127,038 people
Adults with and without high blood pressure. WHO-commissioned reviewers pooled randomized potassium trials plus large observational cohorts tracking stroke and heart disease.
The finding
Getting more potassium brings blood pressure down, and the drop is meaningful in people who already have hypertension. It also tracked with a lower chance of stroke. The link to heart disease overall didn't reach statistical significance — the clearest wins are blood pressure and stroke.
The answer
−3.5 mmHg systolic (hypertensives)
Up to −7.2 mmHg at higher intakes · 24% lower stroke risk. No significant effect on heart disease overall.
If your blood pressure runs high, eating more potassium-rich food — beans, potatoes, leafy greens, bananas, yogurt — can shave a few points off, and shifts the odds against stroke. The effect is small per meal but adds up. If you have kidney disease or take certain blood-pressure drugs, check with a doctor before pushing potassium, since your body may not clear it normally.
Micronutrients & Electrolytes
Which minerals actually move your blood pressure?
About this study
Studies pooled
32 meta-analyses
A review of reviews: the authors gathered 32 published meta-analyses on sodium, potassium, calcium, and magnesium and compared how strongly each shifts blood pressure.
The finding
Of the four minerals, potassium had the most consistent blood-pressure-lowering effect. Cutting sodium helped too, but the size of the effect swung widely depending on the group studied. Calcium and magnesium played smaller, more situational roles.
The answer
Potassium
Systolic drop — potassium: 3.5–9.5 mmHg · sodium reduction: 0.7–8.9 mmHg. Calcium and magnesium: smaller effects.
For blood pressure, the highest-leverage mineral moves are getting enough potassium and not overdoing sodium — the two work as a pair. Calcium and magnesium matter for other reasons but are weaker blood-pressure levers. Tracking sodium and potassium together, as the app does, captures most of the dietary effect on blood pressure.
Micronutrients & Electrolytes
How much sodium do endurance athletes really need?
About this study
Type
Systematic review
Endurance and ultra-endurance athletes — runners, cyclists, triathletes — who lose large amounts of sodium in sweat over long sessions. Reviewers synthesized the sodium-balance and performance literature.
The finding
For long-duration exercise, sodium sits in a Goldilocks zone: too little during hours of heavy sweating can trigger dangerous low-sodium blood levels (hyponatremia) and cramps, while too much carries its own risks. There's no single right number — it depends on how much you sweat and how salty your sweat is.
The answer
Individualize it
Matters most for sessions over ~2 hours. Pair sodium with fluid — over-drinking plain water is a main hyponatremia trigger.
For everyday training under about two hours, normal food covers your sodium. For long, hot, sweaty sessions and ultra-endurance events, you need a deliberate sodium-and-fluid plan matched to your own sweat rate — and the biggest danger is drinking lots of plain water without replacing salt. If you race long, test your sweat losses rather than guessing.
Micronutrients & Electrolytes
Is there a sweet spot for potassium and blood pressure?
About this study
Studies pooled
32 RCTs
Doses tested
30–140 mmol/day
Mostly adults with hypertension in crossover trials. Researchers modeled the shape of the potassium-blood-pressure curve rather than just an average effect.
The finding
More potassium lowers blood pressure — but only up to a point. The benefit is biggest going from low to moderate intake, flattens out, and at very high supplemental doses blood pressure actually crept back up. It's a sweet spot, not "more is always better."
The answer
Enough, not excess
Most benefit reaching adequate intake; effect fades past ~30 mmol/day extra and reverses above ~80. Strongest in hypertensives on high-sodium diets.
Aim to reach an adequate potassium intake from food rather than megadosing supplements — the blood-pressure payoff is front-loaded at getting from low to enough. Piling on high-dose potassium pills isn't just wasteful, it can backfire, and it's risky if your kidneys or medications limit how you clear potassium. Food-first is the safe way to hit the sweet spot.
Vitamin C — Antioxidant Function & Exercise Recovery
Micronutrients & Electrolytes
Do antioxidant vitamins protect muscles from exercise damage?
About this study
Studies pooled
21 studies
Studies gave vitamin C, vitamin E, or both — acutely before exercise or as chronic supplementation — and measured muscle-damage markers like creatine kinase after training.
The finding
Across 21 studies the results were all over the map: some showed lower muscle-damage markers with vitamin C or E, most showed no difference. There's no dependable protective effect — and because these vitamins mop up the free radicals that trigger adaptation, high doses may actually work against you.
The answer
Not reliably
Results mixed and inconclusive. High-dose antioxidants may blunt the training adaptations you're working for.
Don't take high-dose vitamin C or E hoping to reduce muscle damage or soreness — the evidence doesn't support it, and routinely megadosing antioxidants around training can dull the signal your muscles use to get fitter and stronger. Get these vitamins from food; save any supplementation for correcting an actual dietary shortfall.
Micronutrients & Electrolytes
Does vitamin C actually help you recover after exercise?
About this study
RCTs pooled
18 trials
People
313 adults
Healthy adults (median age 24, 62% male) given vitamin C versus placebo around a single bout of exercise. Researchers pooled effects on oxidative stress, inflammation, soreness, and strength.
The finding
Vitamin C does damp down the oxidative-stress and inflammation signals your body throws off after a hard session. But that didn't translate into what actually matters to you — it made no difference to how sore you feel or how fast your strength comes back. Blunting those signals may even be counterproductive for adaptation.
The answer
Blunts stress, not soreness
Lowered oxidative stress and IL-6 · No effect on DOMS or strength recovery.
Taking vitamin C won't make you less sore or get your strength back faster, even though it changes bloodwork markers. Since those same oxidative signals help drive fitness gains, routinely megadosing around workouts is more likely to hurt than help. Eat vitamin-C-rich foods for general health and skip the high-dose recovery pills.
Micronutrients & Electrolytes
What does the newest vitamin C recovery evidence show?
About this study
RCTs pooled
12 trials
Certainty
Low to very low
The most recent pooled analysis of vitamin C versus placebo around exercise, graded with GRADE. Several outcomes rested on just two or three small trials, so confidence is limited.
The finding
The newest evidence agrees with the older meta-analyses: vitamin C doesn't meaningfully change the main inflammation and oxidative-stress markers after exercise. One marker, CRP, did drop — but on just two small trials the authors themselves rate as low-to-very-low certainty. Nothing here supports megadosing.
The answer
No clear benefit
IL-6 and MDA: no effect. CRP: reduced but only 2 trials, very-low certainty.
The current best evidence still doesn't give you a reason to take high-dose vitamin C for recovery — the one positive signal (CRP) is too thin to bank on. Cover vitamin C through food, and don't expect a supplement to blunt post-workout inflammation in a way that helps you. Bigger, better trials are needed before any of this changes.
B Vitamins — Energy Metabolism & Exercise Requirements
Micronutrients & Electrolytes
Do B vitamins give you energy for workouts?
About this study
Type
Narrative review
A review of how the B-complex vitamins feed into energy metabolism during exercise, and how training affects the body's need for them.
The finding
B vitamins are the helper molecules that let your body convert food into energy — without enough of them, that machinery stalls. Exercise does raise your turnover of a few (like B6 and riboflavin). But "needed for energy production" doesn't mean "adding more gives you more energy" once you're already getting enough.
The answer
Only if you're short
Training nudges up the need for B6 and riboflavin — a bigger deal if your diet is already marginal.
If you eat a reasonable, varied diet you're almost certainly getting enough B vitamins, and topping up won't give you an energy boost — that's a marketing promise, not a physiology one. The people who benefit from more are those running low: heavy trainers on restrictive diets, or anyone with a genuine shortfall. Cover them with food first.
Micronutrients & Electrolytes
Can a B-complex supplement improve your endurance?
About this study
People
32 adults
Duration
28 days
Healthy, non-athlete adults in a crossover design (each person tried both supplement and placebo). The supplement was a commercial B-complex product, so treat this as promising rather than definitive.
The finding
Over four weeks, taking a B-complex let these non-athletes run about 26% longer before exhaustion and built up less lactate and ammonia — the chemicals tied to that "legs are done" feeling. It's a single small trial in untrained people using a branded product, so it points a direction rather than settling the question.
The answer
1.26× time to exhaustion
Also lower exercise lactate and ammonia. Small trial (n=32) in untrained adults; industry product.
This hints a B-complex might help endurance, but read it carefully: the people were untrained, the group was small, and the product was commercial. It doesn't prove a B-complex will boost a well-fed, trained athlete. If your diet already covers B vitamins, the likeliest explanation for any benefit is topping up a marginal intake — not a true ergogenic effect.
Micronutrients & Electrolytes
Does training raise how much B vitamins you need?
About this study
Type
Narrative review
A review of metabolic studies on thiamin, riboflavin, and vitamin B6 in active people. The author is careful that the evidence is limited and not fully consistent.
The finding
Exercise seems to increase the body's need for riboflavin and B6 a little, mostly by speeding their turnover and loss. The catch: the extra need is small, blood levels usually stay normal, and it only really bites in people whose diets are already marginal — those dieting or eating poorly. Thiamin wasn't directly tested.
The answer
Slightly higher
Matters most for active people who diet or eat poorly; effect is small and evidence is mixed.
Training bumps your B-vitamin needs up modestly, not dramatically — and a normal, varied diet easily covers the difference. The people who should pay attention are active dieters or anyone with a restrictive, low-variety diet, who can slip into a shortfall. For everyone else, no special B-vitamin dosing is needed just because you exercise.
Magnesium — Widespread Deficiency & Metabolic Consequences
Micronutrients & Electrolytes
Are most people getting enough magnesium?
About this study
US adults below need
~48 %
A review of US national nutrition-survey data and the observational links between low magnesium and chronic disease. It synthesizes population data rather than running a new experiment.
The finding
Roughly half of Americans don't get enough magnesium from food, and the shortfall is easy to miss — the standard blood test stays normal until stores are badly depleted. The authors argue this quiet, widespread gap contributes to conditions like high blood pressure, diabetes, and osteoporosis, though the links are observational.
The answer
~48% of US adults fall short
Gap is widest in older adults, some minority groups, and people with type 2 diabetes.
Magnesium is one of the nutrients people most commonly under-eat, so it's worth a look at your diet — leafy greens, nuts, seeds, legumes, and whole grains are the richest sources. A normal blood magnesium result doesn't guarantee you're replete, so focus on habitually eating magnesium-rich food rather than relying on a lab number. These links to disease are associations, not proof, but the food advice is low-risk.
Micronutrients & Electrolytes
Could low magnesium be quietly harming your heart?
About this study
Type
Mechanism review
A mechanistic argument review, not a trial. The authors lay out the biological pathways linking low magnesium to heart disease and make the case that current testing misses most deficiency.
The finding
Because more than 99% of your body's magnesium sits inside cells, a normal blood test can mask a real deficiency. The authors argue this hidden shortfall drives heart problems — magnesium normally acts like a built-in calcium blocker, and without enough, arteries stiffen and calcify and the heart's rhythm gets less stable. It's a strong hypothesis built on mechanism, not a controlled trial.
The answer
Plausibly, yes
Serum magnesium can look normal despite depleted stores. Processed and refined foods are low in magnesium.
Treat this as a well-reasoned warning rather than proof: the case that hidden magnesium deficiency harms the heart rests on mechanism, not outcome trials. Still, the takeaway is low-risk and worth acting on — lean toward whole, minimally-processed foods rich in magnesium (greens, nuts, seeds, legumes, whole grains) instead of refined ones, and don't assume a normal blood test means you're covered.
Micronutrients & Electrolytes
Does low magnesium raise your diabetes risk?
About this study
Type
Mechanism review
A review of the mechanisms linking magnesium to insulin resistance, plus the observational and trial evidence on magnesium and type 2 diabetes.
The finding
Magnesium and diabetes feed into each other: too little magnesium jams up insulin's signalling machinery and worsens insulin resistance, while diabetes itself makes you lose more magnesium in urine. People who eat more magnesium tend to develop type 2 diabetes less often, and topping up improved blood-sugar markers in most supplementation trials.
The answer
It worsens insulin resistance
Cohort meta-analyses cited by the review: each ~100 mg/day more magnesium ≈ 8–15% lower type-2 diabetes risk (association).
If you're working on blood sugar or body composition, magnesium is a nutrient worth getting right — a shortfall makes your cells less responsive to insulin. The link between higher magnesium intake and lower diabetes risk is consistent but observational, so think "eat enough," not "supplement to prevent diabetes." Prioritize magnesium-rich whole foods, and if you have diabetes, know the disease itself can deplete you further.