Herbs & botanicals

Soy isoflavones

Plant estrogens from soybeans. Taken for menopause symptoms and bones – studies are mixed.

12 products from US online stores, sorted by what 50 mg of soy isoflavones costs – not by the price per pack.

3.5¢Lowest cost
per 50 mg soy isoflavones

Prices checked Nov 1, 2026, US
No paid placements

What does 50 mg mean?

soy isoflavones per serving in most of the products we checked: 13.5–250 mgsoy isoflavones per serving in most of the products we checked

50 mg is a fixed amount to compare by: half of the 12 products we checked have up to 125 mg per serving, the other half more.
There’s no official daily amount for soy isoflavones.

We compare by 50 mg only so products line up – it’s not a recommendation. Not medical advice.

Where products miss quality points

How the 12 products score

Very good 90+: 0
Good 75+: 12
Fair 60+: 0
Low under 60: 0

have no seal from an independent testing program: 12 of 12have no seal from an independent testing program10 of 30 testing points for GMP, 15 for the 3 whose label says “third-party tested”

The full 30 testing points need an independent test. Every supplement sold in the US is made under the FDA’s GMP rules – the maker checks its own products, which gives 10 points. A seal from a testing program like NSF, USP or Informed Choice means a lab outside the company checks that what’s inside matches the label. Most brands don’t take part. That doesn’t make a product bad – without a seal, a clean product still gets up to 80.

We find seals on the label and in NSF’s public lists. USP and Informed Choice don’t let us search their lists automatically, so a seal that’s only in their lists can be missing. How the score works

Good to know

Fact: 1,798%more per 50 mg for the most expensive product than for the cheapest.

How we checked: one-time price for each size in the store’s US online shop, before sales tax and shipping, without subscriptions or coupons. Prices change often, so check the store before you buy. More on how we check

The amount we compare by only makes products comparable – it is not a dosage recommendation. Not medical advice.

How we calculate

Cost per dose = price ÷ (servings × amount per serving) × comparison amount. Example: $119.99 for 74 servings with 24 g of protein each is 1,776 g of protein. $119.99 ÷ 1,776 g × 30 g = $2.03 per 30 g of protein.

Found a mistake or a product we should add? Email us

Soy isoflavones

What does 50 mg mean?

Where products miss quality points

Pack size

Soy Isoflavones, 150 mg

Soy Isoflavones

Soy Isoflavones Extract, Standardized

Soy Isoflavones Extract

Genistein from Sophora Japonica, 125 mg

Genistein from Sophora Japonica - Soy Free

Women's Soy Isoflavones

Genistein

Genistein

Soy Isoflavones, 750 mg

Non-Gmo Soy Isoflavones

Soy Isoflavones, 750 mg

Good to know