Is a higher dose always better?

No. Dose-fit rewards landing inside the range studied for the outcome — over-dosing (common with melatonin) or under-dosing both lower the score. The goal is the effective dose, not the biggest number.

What does the Value score mean?

The Value score compares a product's price per serving with clinically relevant products ranked for the same outcome. A score of 50 is the typical price; above 50 means better value than typical, while below 50 means the product costs more than typical. It is a 0–100 value signal, not a percentile.

Why is the cheapest product not #1?

Cost is only one input. The cheapest pick here is a citrate form with weaker absorption and a stock-risk flag, so it leads on Value-for-cost but trails on the composite that also weighs evidence, dose fit and availability.

Are these affiliate links?

Retailer links may be affiliate links and DoseRank may earn a commission. Rankings and placement are determined by the scoring model only — never by payment from a brand.

Is this medical advice?

No. DoseRank summarizes evidence to help you choose; it is not a substitute for a clinician, especially if you are pregnant, breastfeeding, on medication, or managing a health condition.

Improve kidney function

What this outcome means

Kidney function is how well your kidneys filter waste, balance fluids, and clear toxins from your blood. On DoseRank it maps to a defined health outcome built from human studies on eGFR, serum creatinine, and urinary albumin – data sourced from open sources and specialized resources. DoseRank is not medical advice.

Who it's for

Early declineAdults whose lab numbers show filtration slipping over time.

Diabetes or hypertensionPeople whose conditions put steady strain on the kidneys.

Aging kidneysOlder adults wanting to protect filtration as they age.

Stack buildersAlready taking supplements such as Astragalus and want the dose right.

Evidence level

78Moderate-strong

Astragalus – has moderate public evidence for this outcome. This usually means there are smaller or mechanistic studies, but not randomized human trials. A DoseFit Score of 67 means this product's ingredient forms and doses are close to what was used in the studies behind this ranking - DoseRank weights each product ingredient.

Best available ingredients

Astragalus is the best supported ingredient signal for this outcome.

Dose partly matchedDoseFit 67

Scores reward products dosed inside or above the studied range, not just the right ingredient. Examples: In range: Astragalus 1000 mg vs 1000-3000 mg.

Processed

441

Available

441

Ingredients

Brands

127

Coverage

100%

How to read the scores

What every metric means

Each score is 0–100. Higher is better for every metric below.

CompositeThe overall DoseRank score — a weighted blend of clinical strength, evidence, dose fit, trust and value.Higher is better

ClinicalHow strongly the formula's ingredients and doses match what clinical studies used for this outcome.Higher is better

EvidenceHow much published human research backs the formula's key ingredients for this outcome — both how many studies exist and how strong they are.Higher is better

ValueHow the price per serving compares with similar products for this outcome — 50 is the typical price, higher means better value for your money.Higher is better

TrustHow well customers rate this product, with extra weight given to ratings backed by a large number of reviews.Higher is better

PopularityHow strongly this product sells compared with the other ranked products for this outcome.Higher is better

This legend covers the scores on this page — for data sources, scoring weights, and limits, read the full methodology →

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Get a personal report

A saved, shareable breakdown: your matched products, dose math, interaction flags to discuss with a clinician, and a price-tracked stack you can revisit.

Questions

Frequently asked

Each product gets a composite score blending clinical strength, evidence, dose fit, trust and value. The #1 on the DoseRank tab has the highest composite; the other tabs re-rank the same products by Value, Trust, or Popularity. Placement is never paid.

Improve kidney function

What this outcome means

Who it's for

Early declineAdults whose lab numbers show filtration slipping over time.

Diabetes or hypertensionPeople whose conditions put steady strain on the kidneys.

Aging kidneysOlder adults wanting to protect filtration as they age.

Stack buildersAlready taking supplements such as Astragalus and want the dose right.

Evidence level

78Moderate-strong

Best available ingredients

Astragalus is the best supported ingredient signal for this outcome.

Dose partly matchedDoseFit 67

Scores reward products dosed inside or above the studied range, not just the right ingredient. Examples: In range: Astragalus 1000 mg vs 1000-3000 mg.

Processed

441

Available

441

Ingredients

Brands

127

Coverage

100%

Relevant ingredients

Which ingredient types matter for kidney functionOpen to see which ingredient types matter for kidney function

251 products across 2 ingredient types — open to filter the ranking.

Use types to filter ranked products

Botanicals/Herbal Extracts

199 products

Concentrated plant and herbal extracts standardized to actives. Potency depends on the extract ratio and marker content, not raw weight.

Typical: , , , ...

Adsorbents & Inert Functional Materials

52 products

Binding agents like charcoal and silica that adsorb or stabilize. Functional and non-nutritive – they can bind nutrients, so time them apart.

Typical:

Top decision cards

Best products for kidney function

Ranking by · Composite outcome score

Best overall — the composite outcome score.

Top pick · DoseRank

Why this ranks #1 for kidney function

NOW Foods, Astragalus, 500 mg, 100 Veg Capsules

NOW Foods$0.14 / serving4.7 · 3,527Available now

Also helps with

Albuminuria or proteinuria

Immune function

Why this ranks here

Evidence fitAstragalus has moderate human evidence for this outcome.
Dose fitAstragalus at 1000 mg lands inside the studied 1000-3000 mg window.
Price / serving$0.14 per serving — mid price tier for this outcome.
AvailabilityIn stock across major retailers; 99% availability confidence.
TrustStrong trust signals — consistently high marks from verified buyer ratings.

The numbers

1000 mgIn rangeinside the studied 1000-3000 mg window

Compare top 3 Product data Open at retailer

The rest of the ranking · DoseRank

Top 10 ranked products

Nature's Way, Astragalus Root, 180 Vegan Capsules (470 mg per Capsule)

Nature's WayClinical87Dose fit71Popularity76$0.25/ serving

Nutricost, Organic Astragalus Root Powder, Unflavored, 16.2 oz (454 g)

NutricostClinical86Dose fit67Popularity50$0.04/ serving

Vitacost, Astragalus Root, 100 Capsules (500 mg per Capsule)

VitacostClinical87Dose fit72Popularity68$0.14/ serving

Nature's Answer, Astragalus Root, Fluid Extract, Alcohol-Free, 2,000 mg, 1 fl oz (30 ml)

Nature's AnswerClinical87Dose fit78Popularity68$0.76/ serving

Oregon's Wild Harvest, Organic Astragalus, 180 Organic Vegan Capsules (375 mg per Capsule)

Oregon's Wild HarvestClinical86Dose fit68Popularity50$0.50/ serving

Vitacost, Astragalus Root Liquid Extract, Alcohol Free, 1 fl oz (30 ml)

VitacostClinical87Dose fit78Popularity50$0.40/ serving

Oregon's Wild Harvest, Organic Astragalus, 90 Organic Vegan Capsules (375 mg per Capsule)

Oregon's Wild HarvestClinical86Dose fit68Popularity30$0.69/ serving

Gaia Herbs, Astragalus Supreme, 60 Liquid Phyto-Caps®

Gaia HerbsClinical86Dose fit70Popularity30$0.94/ serving

Oregon's Wild Harvest, Organic Astragalus, 1 fl oz (30 ml)

Oregon's Wild HarvestClinical86Dose fit67Popularity30$0.57/ serving