Form Comparisons
Side-by-side comparisons of supplement forms: elemental content, absorption evidence, tolerance, and cost.
Vitamin D
Magnesium
Magnesium Aspartate vs Magnesium Chloride
Both are rated high for absorption, and head-to-head human data do not reliably separate them.
Magnesium Aspartate vs Magnesium Citrate
Both are rated high for absorption, and head-to-head human data do not reliably separate them.
Magnesium Aspartate vs Magnesium Glycinate
Both are rated high for absorption, and head-to-head human data do not reliably separate them.
Magnesium Aspartate vs Magnesium Lactate
Both are rated high for absorption, and head-to-head human data do not reliably separate them.
Magnesium Aspartate vs Magnesium Malate
Both are rated high for absorption, and head-to-head human data do not reliably separate them.
Magnesium Aspartate vs Magnesium Oxide
Magnesium aspartate is substantially better absorbed than magnesium oxide (poorly soluble at intestinal pH).
Magnesium Aspartate vs Magnesium Taurate
Absorption evidence is stronger for magnesium aspartate (rated high) than for magnesium taurate (rated moderate), though the gap reflects thinner data more than demonstrated poor absorption.
Magnesium Aspartate vs Magnesium L-Threonate
Absorption evidence is stronger for magnesium aspartate (rated high) than for magnesium L-threonate (rated moderate), though the gap reflects thinner data more than demonstrated poor absorption.
Magnesium Chloride vs Magnesium Citrate
Both are rated high for absorption, and head-to-head human data do not reliably separate them.
Magnesium Chloride vs Magnesium Glycinate
Both are rated high for absorption, and head-to-head human data do not reliably separate them.
Magnesium Chloride vs Magnesium Lactate
Both are rated high for absorption, and head-to-head human data do not reliably separate them.
Magnesium Chloride vs Magnesium Malate
Both are rated high for absorption, and head-to-head human data do not reliably separate them.
Magnesium Chloride vs Magnesium Oxide
Magnesium chloride is substantially better absorbed than magnesium oxide (poorly soluble at intestinal pH).
Magnesium Chloride vs Magnesium Taurate
Absorption evidence is stronger for magnesium chloride (rated high) than for magnesium taurate (rated moderate), though the gap reflects thinner data more than demonstrated poor absorption.
Magnesium Chloride vs Magnesium L-Threonate
Absorption evidence is stronger for magnesium chloride (rated high) than for magnesium L-threonate (rated moderate), though the gap reflects thinner data more than demonstrated poor absorption.
Magnesium Citrate vs Magnesium Glycinate
Both are well absorbed, and no head-to-head human trial shows one raising magnesium status more than the other.
Magnesium Citrate vs Magnesium Lactate
Both are rated high for absorption, and head-to-head human data do not reliably separate them.
Magnesium Citrate vs Magnesium Malate
Both are rated high for absorption, and head-to-head human data do not reliably separate them.
Magnesium Citrate vs Magnesium Oxide
Citrate is the better choice for raising magnesium status.
Magnesium Citrate vs Magnesium Taurate
Absorption evidence is stronger for magnesium citrate (rated high) than for magnesium taurate (rated moderate), though the gap reflects thinner data more than demonstrated poor absorption.
Magnesium Citrate vs Magnesium L-Threonate
Absorption evidence is stronger for magnesium citrate (rated high) than for magnesium L-threonate (rated moderate), though the gap reflects thinner data more than demonstrated poor absorption.
Magnesium Glycinate vs Magnesium Lactate
Both are rated high for absorption, and head-to-head human data do not reliably separate them.
Magnesium Glycinate vs Magnesium Malate
Both are gentle, well-absorbed organic forms with similar elemental content (14.1% vs 15.5%), and no trial separates their absorption.
Magnesium Glycinate vs Magnesium Oxide
Glycinate is well absorbed and gentle on the gut; oxide is poorly absorbed and acts mainly as an osmotic laxative.
Magnesium Glycinate vs Magnesium Taurate
Absorption evidence is stronger for magnesium glycinate (rated high) than for magnesium taurate (rated moderate), though the gap reflects thinner data more than demonstrated poor absorption.
Magnesium Glycinate vs Magnesium L-Threonate
Glycinate is the better choice for correcting low magnesium: it delivers about 70% more magnesium per gram of compound (14.1% vs 8.3%) at a fraction of the cost.
Magnesium Lactate vs Magnesium Malate
Both are rated high for absorption, and head-to-head human data do not reliably separate them.
Magnesium Lactate vs Magnesium Oxide
Magnesium lactate is substantially better absorbed than magnesium oxide (poorly soluble at intestinal pH).
Magnesium Lactate vs Magnesium Taurate
Absorption evidence is stronger for magnesium lactate (rated high) than for magnesium taurate (rated moderate), though the gap reflects thinner data more than demonstrated poor absorption.
Magnesium Lactate vs Magnesium L-Threonate
Absorption evidence is stronger for magnesium lactate (rated high) than for magnesium L-threonate (rated moderate), though the gap reflects thinner data more than demonstrated poor absorption.
Magnesium Malate vs Magnesium Oxide
Magnesium malate is substantially better absorbed than magnesium oxide (poorly soluble at intestinal pH).
Magnesium Malate vs Magnesium Taurate
Absorption evidence is stronger for magnesium malate (rated high) than for magnesium taurate (rated moderate), though the gap reflects thinner data more than demonstrated poor absorption.
Magnesium Malate vs Magnesium L-Threonate
Absorption evidence is stronger for magnesium malate (rated high) than for magnesium L-threonate (rated moderate), though the gap reflects thinner data more than demonstrated poor absorption.
Magnesium Oxide vs Magnesium Taurate
Magnesium taurate is substantially better absorbed than magnesium oxide (poorly soluble at intestinal pH).
Magnesium Oxide vs Magnesium L-Threonate
Magnesium L-threonate is substantially better absorbed than magnesium oxide (poorly soluble at intestinal pH).
Magnesium Taurate vs Magnesium L-Threonate
Both are rated moderate for absorption, and head-to-head human data do not reliably separate them.
Creatine
Buffered Creatine vs Creatine Hydrochloride
Neither has beaten plain monohydrate: buffered creatine matched it in Jagim 2012, and HCl's extra solubility does not raise muscle uptake, which the transporter limits.
Buffered Creatine vs Creatine Monohydrate
Choose monohydrate.
Creatine Ethyl Ester vs Creatine Hydrochloride
HCl at least delivers creatine; ethyl ester largely does not, because it breaks down to creatinine at gut pH and failed to raise muscle creatine against monohydrate in Spillane 2009.
Creatine Ethyl Ester vs Creatine Monohydrate
Monohydrate wins outright.
Creatine Hydrochloride vs Creatine Monohydrate
Monohydrate is the form behind nearly all of the strength, lean mass, and safety data, and it costs a fraction of HCl.
Creatine Monohydrate vs Creatine Nitrate
Choose monohydrate.
Omega-3 (EPA and DHA)
Algal Oil vs Ethyl Ester Fish Oil
Algal oil is the choice for vegans, fish allergy, and anyone avoiding fish, and it absorbs like natural triglyceride oil.
Algal Oil vs Krill Oil
Both cost a lot per gram of EPA+DHA.
Algal Oil vs rTG Fish Oil
rTG fish oil is the better tool for concentrated EPA+DHA in few capsules, and it absorbs well even without a large meal (Dyerberg 2010).
Algal Oil vs Triglyceride Fish Oil
Both are triglyceride oils and absorb alike; the difference is source and price.
Ethyl Ester Fish Oil vs Krill Oil
For dose, ethyl ester wins easily: concentrated capsules carry several times the EPA+DHA of krill at a lower cost per gram, and prescription omega-3s use this form.
Ethyl Ester Fish Oil vs rTG Fish Oil
Both are concentrated, but rTG converts the ethyl esters back to triglycerides and produced higher plasma EPA+DHA than ethyl esters in Dyerberg 2010.
Ethyl Ester Fish Oil vs Triglyceride Fish Oil
Natural triglyceride oil is the native form and absorbs well, but at about 30% EPA+DHA it takes many capsules to pass 1 g.
Krill Oil vs rTG Fish Oil
rTG fish oil delivers far more EPA+DHA per capsule and per dollar, and it absorbs well without a heavy meal.
Krill Oil vs Triglyceride Fish Oil
Plain triglyceride fish oil gives more EPA+DHA per dollar and absorbs well with food.
rTG Fish Oil vs Triglyceride Fish Oil
Both are triglycerides; rTG is the concentrated version, distilled as ethyl esters and converted back.
Whey Protein
Hydrolyzed Whey Protein vs Whey Protein Concentrate
Choose concentrate for muscle gain and protein targets: it is the cheapest per gram, and hydrolysate's faster peptide appearance has not produced more muscle than intact whey.
Hydrolyzed Whey Protein vs Whey Protein Isolate
If concentrate bothers your gut, try isolate before hydrolysate: isolate removes most lactose, costs less, and tastes better.
Whey Protein Concentrate vs Whey Protein Isolate
Both deliver the same leucine-rich protein with similar digestion.
Iron
Carbonyl Iron vs Ferrous Sulfate
Ferrous sulfate is the reference repletion form: cheap and reliably absorbed, especially as a single morning dose on alternate days.
Carbonyl Iron vs Iron Bisglycinate
Bisglycinate is the better choice for most people who struggle with iron: it is less affected by dietary phytates than other forms, and trials report fewer GI complaints.
Ferrous Fumarate vs Ferrous Gluconate
These are the same ferrous iron, absorbed by the same transporter, with the same side effects per milligram of elemental iron.
Ferrous Fumarate vs Ferrous Sulfate
Same ferrous iron, same DMT1 absorption, same GI side effects per milligram of elemental iron.
Ferrous Fumarate vs Iron Bisglycinate
Fumarate is the cheap, iron-dense salt (33% elemental) in most prenatal vitamins.
Ferrous Gluconate vs Ferrous Sulfate
Gluconate is not gentler per milligram of iron; it only seems so because each tablet holds less (12% elemental vs 20% for sulfate).
Ferrous Gluconate vs Iron Bisglycinate
Gluconate feels gentler than sulfate only because its tablets hold less iron.
Ferrous Sulfate vs Heme Iron Polypeptide
Ferrous sulfate is the right first choice for iron deficiency anemia: cheap, proven, and best taken as a single morning dose on alternate days.
Ferrous Sulfate vs Iron Bisglycinate
Ferrous sulfate is the reference repletion form and the cheapest per milligram of iron, and alternate-day morning dosing improves both absorption and tolerance.
Heme Iron Polypeptide vs Iron Bisglycinate
Both are the gentle options when iron salts fail.
Zinc
Zinc Acetate vs Zinc Gluconate
For cold lozenges, acetate is the stronger choice: it releases a higher fraction of free zinc ions in the mouth, and the lozenge trials used acetate or gluconate at about 75 mg zinc a day, started at the first symptoms.
Zinc Bisglycinate vs Zinc Citrate
Both are well absorbed.
Zinc Bisglycinate vs Zinc Gluconate
Absorption is comparable, and both work at 15-30 mg elemental zinc.
Zinc Bisglycinate vs Zinc Oxide
Bisglycinate is the better choice for targeted zinc: it does not depend on stomach acid, is less affected by phytates, and is gentle on an empty stomach.
Zinc Bisglycinate vs Zinc Picolinate
Both are chelates sold at a modest premium over gluconate, and neither has large comparative trials.
Zinc Citrate vs Zinc Gluconate
Absorption is the same: Wegmuller 2014 measured equal fractional absorption for citrate and gluconate, both better than oxide.
Zinc Citrate vs Zinc Oxide
Citrate absorbed better than oxide in Wegmuller 2014, at similar cost.
Zinc Citrate vs Zinc Picolinate
Citrate's absorption is documented in a modern isotope study (Wegmuller 2014); picolinate's advantage rests on one small 1987 trial.
Zinc Gluconate vs Zinc Oxide
Gluconate absorbs better: oxide needs stomach acid to dissolve, showed lower fractional absorption than gluconate in Wegmuller 2014, and does worse still with acid-suppressing drugs.
Zinc Gluconate vs Zinc Picolinate
Gluconate has the stronger absorption data, including Wegmuller 2014, and costs less.
Zinc Gluconate vs Zinc Sulfate
Both are soluble salts that release ionic zinc and absorb well.
Zinc Oxide vs Zinc Picolinate
Picolinate is the better standalone supplement: soluble forms consistently out-absorb oxide, which needs stomach acid and underperformed in Wegmuller 2014.
Zinc Oxide vs Zinc Sulfate
Sulfate is soluble and absorbs well without depending on stomach acid; oxide needs acid to dissolve and absorbs less.
Zinc Picolinate vs Zinc Sulfate
Sulfate is the clinical form for documented deficiency and is cheap, but it causes the most nausea and metallic taste of the common salts.
Vitamin B12
Adenosylcobalamin vs Cyanocobalamin
Cyanocobalamin is the studied, stable, cheap default, and cells convert it into both active cofactors, adenosylcobalamin and methylcobalamin.
Adenosylcobalamin vs Hydroxocobalamin
These rarely compete: hydroxocobalamin is the injectable form, retained longer than cyanocobalamin so injections can be spaced out, and it is the standard injection in the UK.
Adenosylcobalamin vs Methylcobalamin
These are the two active coenzymes: methylcobalamin works in the cytosol for methionine synthase, adenosylcobalamin in mitochondria for methylmalonyl-CoA mutase.
Cyanocobalamin vs Hydroxocobalamin
For oral supplements, cyanocobalamin is the cheaper, more stable, better-studied choice.
Cyanocobalamin vs Methylcobalamin
Both use the same absorption pathways, and cells strip the attached group and rebuild both active cofactors, so dose matters more than form.
Hydroxocobalamin vs Methylcobalamin
Methylcobalamin is the oral choice of the two, widely sold as 500-1,000 mcg tablets and lozenges.
Folate
Folic Acid vs Folinic Acid
Folic acid is the form proven to prevent neural tube defects and the right default for anyone who could become pregnant.
Folic Acid vs L-Methylfolate
Folic acid has the neural tube defect evidence and is cheap, but DHFR activates it slowly, so doses above roughly 200-400 mcg leave unmetabolized folic acid in blood, with unclear significance.
Folinic Acid vs L-Methylfolate
Methylfolate is the end product and bypasses both DHFR and MTHFR; folinic acid bypasses DHFR but still passes through MTHFR.
Vitamin B6
Melatonin
Caffeine
Caffeine Anhydrous vs Caffeine Citrate
Once dissolved, they are the same caffeine; the difference is labeling.
Caffeine Anhydrous vs Dicaffeine Malate
Dicaffeine malate dissociates to ordinary caffeine in the gut, and claims of smoother onset or fewer stomach effects rest on limited manufacturer-linked data.
Fiber
Glucomannan vs Psyllium Husk
Psyllium is the better-evidenced choice for constipation, IBS-related diarrhea, and LDL lowering, and it carries an FDA heart health claim.
Inulin vs Partially Hydrolyzed Guar Gum
Both are fermentable prebiotic fibers, but PHGG ferments slowly and is far easier on the gut, while inulin ferments fast and commonly triggers gas and bloating.
Inulin vs Psyllium Husk
These do different jobs.
Inulin vs Wheat Dextrin
Both are soluble, non-viscous, fermented fibers that dissolve in drinks, and neither normalizes stool or lowers LDL the way psyllium does.
Methylcellulose vs Psyllium Husk
Psyllium does more: it softens hard stool, firms loose stool, and lowers LDL cholesterol.
Methylcellulose vs Wheat Dextrin
Methylcellulose (Citrucel) is a bulk-forming laxative that bacteria do not ferment, so it relieves constipation with almost no gas.
Partially Hydrolyzed Guar Gum vs Psyllium Husk
Psyllium has the broader evidence for constipation, diarrhea, and LDL lowering.
Partially Hydrolyzed Guar Gum vs Wheat Dextrin
Both dissolve clear in drinks.
Psyllium Husk vs Wheat Dextrin
Wheat dextrin (Benefiber) dissolves clear and adds fiber grams to drinks, but it is non-viscous and lacks psyllium's laxative and cholesterol-lowering effects.
Coenzyme Q10
Vitamin C
Ascorbic Acid vs Ascorbyl Palmitate
Choose ascorbic acid for vitamin C.
Ascorbic Acid vs Calcium Ascorbate
Same vitamin C, same transporter-limited absorption.
Ascorbic Acid vs Liposomal Vitamin C
Below about 500 mg a day, choose ascorbic acid: it is absorbed at 70-90% and costs a fraction of liposomal.
Ascorbic Acid vs Sodium Ascorbate
Absorption is identical; sodium ascorbate is simply the less acidic salt.
Ascorbyl Palmitate vs Liposomal Vitamin C
Both get marketed as fat-friendly vitamin C, but only liposomal is designed as a vitamin C dose.
Calcium Ascorbate vs Sodium Ascorbate
Both are buffered vitamin C salts with the same absorption, gentler on the stomach than ascorbic acid.
Vitamin K2
Vitamin K1 vs Vitamin K2 MK-4
K1 is the dietary vitamin K from leafy greens, taken up mainly by the liver for clotting factors.
Vitamin K1 vs Vitamin K2 MK-7
K1 clears within hours and goes mainly to the liver for clotting factors; MK-7 has a half-life of about 3 days (Schurgers 2007), giving stable blood levels from 90-180 mcg once daily and more reaching tissues outside the liver, such as bone.
Vitamin K2 MK-4 vs Vitamin K2 MK-7
MK-7 is the practical K2 supplement: a long half-life lets 90-180 mcg once daily maintain steady levels.
Selenium
Selenium Yeast vs Selenomethionine
Selenium yeast is mostly selenomethionine in a yeast matrix, so the two behave alike: well absorbed and stored in body proteins.
Selenium Yeast vs Sodium Selenite
Selenium yeast, mostly selenomethionine, is better absorbed and retained, building a protein-bound selenium pool that raises blood levels more.
Selenomethionine vs Sodium Selenate
Selenate is almost completely absorbed, but much of it is lost in urine; selenomethionine is absorbed at over 90% and retained in body proteins.
Selenomethionine vs Sodium Selenite
Selenomethionine is better absorbed (over 90% vs about 50%) and builds a storage pool by replacing methionine in body proteins, while selenite feeds selenoprotein synthesis directly without that pool.
Sodium Selenate vs Sodium Selenite
Both are inorganic forms found mainly in multivitamins.
Chromium
Chromium Chloride vs Chromium Picolinate
All chromium absorbs poorly (about 0.4-2.5%), but picolinate absorbs better than chloride and is the form used in most glucose trials.
Chromium Picolinate vs Chromium Polynicotinate
Picolinate is the most studied form, with better absorption than chloride and a large but inconsistent glucose trial record.
Ashwagandha
Ashwagandha Root and Leaf Extract vs Ashwagandha Root Extract
Root-only extracts such as KSM-66 (at least 5% withanolides, 250-600 mg a day) were used in most of the stress and sleep trials.
Ashwagandha Root and Leaf Extract vs Ashwagandha Root Powder
Root-and-leaf extract delivers a measured withanolide dose in 125-250 mg; raw root powder holds unstandardized, variable amounts and needs 3-6 g a day.
Ashwagandha Root Extract vs Ashwagandha Root Powder
Choose the root extract.
Inositol
40:1 Myo and D-Chiro Inositol vs D-Chiro-Inositol
For PCOS, the 40:1 blend is the safer pick: it mirrors the plasma ratio and performed best for ovulation among the ratios compared in one trial.
40:1 Myo and D-Chiro Inositol vs Myo-Inositol
Myo-inositol alone has the larger PCOS and gestational diabetes evidence base and costs less.
D-Chiro-Inositol vs Myo-Inositol
Myo-inositol is the form with the PCOS, gestational diabetes, and psychiatric trial data, and plain "inositol" on a label means myo.
Berberine
Berberine HCl vs Dihydroberberine
Berberine HCl is the form behind nearly all of the glucose and lipid trials and costs the least; 500 mg with meals two or three times a day limits GI effects.
Berberine HCl vs Lipid-Based Berberine
Berberine HCl has the outcome trials; lipid-based versions (phospholipid, micellar, liposomal) have limited pharmacokinetic data, specific to each product.
Dihydroberberine vs Lipid-Based Berberine
Both try to get around berberine's poor absorption, and neither has outcome trials.
Potassium
Potassium Bicarbonate vs Potassium Chloride
These sit on opposite sides of acid-base balance.
Potassium Bicarbonate vs Potassium Citrate
Both supply an alkali load: bicarbonate directly, citrate after it is metabolized.
Potassium Chloride vs Potassium Citrate
Citrate is metabolized to bicarbonate and alkalinizes the urine, which is why prescription potassium citrate prevents calcium oxalate and uric acid kidney stones.
Potassium Chloride vs Potassium Gluconate
Chloride is the medical standard for low potassium, especially with diuretics, and the main ingredient in salt substitutes; concentrated tablets can irritate the gut, so prescription forms use wax-matrix or microencapsulated release.
Potassium Citrate vs Potassium Gluconate
Both absorb well, but citrate has a clinical use, kidney stone prevention through urinary alkalinization, and carries more potassium per gram (36% vs 17%).
NMN and NAD+
Nicotinamide vs Nicotinamide Riboside
Much of an oral NR dose is converted to nicotinamide before reaching tissues, so the gap between them is smaller than the price suggests.
Nicotinamide vs NMN
NMN raised blood NAD+ metabolites at 250-1,000 mg a day in human trials, but outcome results have been mostly null apart from one small insulin-signaling study.
Nicotinamide vs Oral NAD+
Oral NAD+ is largely broken down to nicotinamide in the gut, so you pay a premium for nicotinamide after digestion.
Nicotinamide Riboside vs NMN
Both raise blood NAD+ in humans, and NMN may be converted to NR before absorption, so their effects likely converge.
Nicotinamide Riboside vs Oral NAD+
Choose NR.
NMN vs Oral NAD+
Choose NMN.
Turmeric and Curcumin
BCM-95 Curcumin vs Colloidal Curcumin
Both are enhanced, piperine-free forms used for osteoarthritis, and their fold-increase claims (about 7x for BCM-95, 27x for Theracurmin) come from different study designs that cannot be ranked against each other.
BCM-95 Curcumin vs 95% Curcumin Extract
The plain 95% extract is the form used in most osteoarthritis trials, and it matched ibuprofen in one large trial despite low blood levels.
BCM-95 Curcumin vs Curcumin Phytosome
Both avoid piperine's drug interactions, and both have small absorption studies that cannot be compared head to head.
BCM-95 Curcumin vs Curcumin with Piperine
Piperine is the cheaper enhancer, but it slows clearance of many drugs.
Colloidal Curcumin vs 95% Curcumin Extract
Plain 95% extract is cheap and matches the osteoarthritis trials at 1,000-1,500 mg a day.
Colloidal Curcumin vs Curcumin Phytosome
Both are piperine-free with osteoarthritis data, and their absorption claims (about 27-fold for Theracurmin, 29-fold total curcuminoids for Meriva) come from studies too different to rank.
Colloidal Curcumin vs Curcumin with Piperine
Curcumin with piperine is the cheapest enhanced option, but piperine interferes with the clearance of many drugs.
95% Curcumin Extract vs Curcumin Phytosome
The plain extract is the cheaper, trial-standard form at 1,000-1,500 mg a day.
95% Curcumin Extract vs Curcumin with Piperine
Piperine blocks curcumin's glucuronidation and efflux, raising plasma curcumin about twentyfold in one study, and it adds almost nothing to the cost.
95% Curcumin Extract vs Turmeric Root Powder
Turmeric root powder is only about 3% curcuminoids, so a 500 mg capsule holds roughly 15 mg, far below the 1,000-1,500 mg used in osteoarthritis trials.
Curcumin Phytosome vs Curcumin with Piperine
Piperine raises curcumin levels by inhibiting drug-metabolizing pathways, which raises levels of other medications too.
Curcumin with Piperine vs Turmeric Root Powder
Turmeric powder delivers food-level curcumin, about 15 mg per 500 mg capsule.
Collagen
Hydrolyzed Collagen Peptides vs Gelatin
Both digest to the same amino acids and collagen peptides, such as prolyl-hydroxyproline.
Hydrolyzed Collagen Peptides vs Undenatured Type II Collagen
These are different products with different mechanisms.
Gelatin vs Undenatured Type II Collagen
Gelatin is a cheap collagen protein taken in grams, with a small study supporting tendon collagen synthesis when taken with vitamin C before exercise.
Probiotics
Bifidobacterium longum 35624 vs De Simone Formulation
These target different conditions.
Bifidobacterium longum 35624 vs Unstudied Multi-Strain Blends
For IBS, choose B.
De Simone Formulation vs Unstudied Multi-Strain Blends
Both contain multiple strains, but only the De Simone formulation was tested as a finished product, at high doses for pouchitis and ulcerative colitis.
Lactobacillus rhamnosus GG vs Unstudied Multi-Strain Blends
Choose LGG.
Lactobacillus rhamnosus GG vs Saccharomyces boulardii
Both have good evidence for preventing antibiotic-associated diarrhea, and the practical difference is that S.
Unstudied Multi-Strain Blends vs Saccharomyces boulardii
Choose S.
Calcium
Calcium Carbonate vs Calcium Citrate
Taken with a meal, carbonate absorbs about as well as citrate and delivers the most calcium per tablet (40% vs 21%) at the lowest cost.
Calcium Carbonate vs Microcrystalline Hydroxyapatite
Carbonate is cheap, well studied, and absorbs well with meals.
Calcium Carbonate vs Tricalcium Phosphate
Both absorb about equally with food, and both can constipate.
Calcium Citrate vs Microcrystalline Hydroxyapatite
Citrate absorbs reliably with or without food and with acid-suppressing drugs, and its absorption is well documented.
Lion's Mane
Lion's Mane Fruiting Body Extract vs Lion's Mane Fruiting Body Powder
Whole fruiting body powder matches the 2009 Mori trial in older adults with mild cognitive impairment, which used 3 g a day.
Lion's Mane Fruiting Body Extract vs Lion's Mane Mycelium
Fruiting body extract is made from the mushroom itself and can be tested for beta-glucan content.
Lion's Mane Fruiting Body Powder vs Lion's Mane Mycelium
Whole fruiting body powder is the mushroom itself and the preparation used in the Mori trial at 3 g a day.
Rhodiola
Rhodiola Root Powder vs Rhodiola SHR-5
Choose SHR-5.
Rhodiola Root Powder vs Standardized Rhodiola Extract
Choose the standardized extract.
Rhodiola SHR-5 vs Standardized Rhodiola Extract
SHR-5 is the specific extract used in most controlled trials for stress-related fatigue, and those results apply to it, not to rhodiola in general.
Glutathione
Liposomal Glutathione vs Reduced Glutathione
Reduced glutathione (Setria) has the longer trial: six months at 1,000 mg a day raised body glutathione stores, even though single doses do not raise plasma levels.
Liposomal Glutathione vs S-Acetyl Glutathione
Both are premium forms with weak human evidence: liposomal has a 12-person uncontrolled pilot, and S-acetyl glutathione has cell studies and scant pharmacokinetic data.
Reduced Glutathione vs S-Acetyl Glutathione
Reduced glutathione has a six-month controlled trial showing higher body stores at 1,000 mg a day.
DHEA
Copper
Copper Bisglycinate vs Copper Gluconate
Both absorb well, and little human evidence separates them.
Copper Bisglycinate vs Cupric Oxide
Choose bisglycinate.
Copper Gluconate vs Cupric Oxide
Gluconate absorbs well; cupric oxide barely does, despite carrying about 80% copper by weight.
Copper Gluconate vs Copper Sulfate
Both are soluble, well-absorbed salts.
Cupric Oxide vs Copper Sulfate
Choose sulfate.
Saw Palmetto
Elderberry
Elderberry Extract vs Elderberry Gummies
Choose the standardized extract.
Elderberry Extract vs Elderberry Syrup
Syrup is the form used in the positive early influenza trials, at 15 mL up to four times a day for 3-5 days, but it carries significant sugar.
Elderberry Gummies vs Elderberry Syrup
Syrup is the trial-tested form for influenza at onset, dosed at 15 mL up to four times a day.
Quercetin
Enzymatically Modified Isoquercitrin vs Quercetin
EMIQ is quercetin glucoside with added glucose units, the same structure that makes onion quercetin well absorbed; it is water soluble and produced much higher plasma quercetin than the aglycone in human studies.
Enzymatically Modified Isoquercitrin vs Quercetin Phytosome
Both fix plain quercetin's poor absorption by different routes: EMIQ uses water-soluble glucosides absorbed after hydrolysis in the small intestine, and Quercefit uses a lecithin complex that raised plasma quercetin up to twentyfold in an industry-funded study.
Quercetin vs Quercetin Phytosome
Plain quercetin is cheap and used in most trials but absorbs poorly, and no human data show that adding bromelain helps.
Vitamin A
Vitamin E
d-Alpha-Tocopherol vs dl-Alpha-Tocopheryl Acetate
Natural d-alpha-tocopherol is a single stereoisomer that the liver retains; synthetic dl-alpha is a mix of eight, of which only four are retained, so it has about half the activity per milligram.
d-Alpha-Tocopherol vs Mixed Tocopherols
Alpha-only supplements lower blood gamma-tocopherol; mixed tocopherols supply alpha plus gamma and delta, closer to vitamin E in food.
d-Alpha-Tocopherol vs Tocotrienols
d-Alpha-tocopherol is the form the liver's transfer protein favors and the one with clinical trial data.
dl-Alpha-Tocopheryl Acetate vs Mixed Tocopherols
Synthetic dl-alpha acetate has about half the activity per milligram of natural alpha and supplies no gamma-tocopherol.
Mixed Tocopherols vs Tocotrienols
Mixed tocopherols are the better general vitamin E supplement: natural alpha, plus gamma and delta, close to the food profile.