PlainVitamins

Fos

by Source Naturals · powder · 100 grams

  • On the market (NIH)
  • UPC 0 21078 00577 3
  • DSLD label 213554
  • Serving 3.3 g (1 rounded teaspoon)
  • 30 servings

Fos by Source Naturals lists one ingredient: 3.3 g of fructooligosaccharides per serving of 3.3 g. Its current label entered the NIH Dietary Supplement Label Database on February 26, 2020.

What is in Fos?

Each row as the label prints it, per serving of 3.3 g. The capsule beside an amount places it among every product in the NIH database that lists the same ingredient: the bar is the middle half of their amounts, the line in it the median, the whiskers the 10th and 90th percentiles; the green tick is the FDA Daily Value and the red dashed tick the adult upper limit (IOM).

Fos: Supplement Facts rows against the market (DSLD label 213554, January 2026 release)
IngredientAmount% DVAmong products listing it
Calories5 Calories
Total Carbohydrates3 g1%Carbohydrate in FOS against 21,979 products3 g per serving; the middle half of products list 1 g to 6 g, the median 3 g.3 g

47% of 21,979 products listing carbohydrate give more (median 3 g).

Dietary Fiber3 g12%Fiber in FOS against 6,987 products3 g per serving; the middle half of products list 1 g to 4 g, the median 2 g.3 g

Higher than 63% of 6,987 products listing fiber (median 2 g).

Fructooligosaccharides3.3 gFructo-Oligosaccharides in FOS against 526 products3,300 mg per serving; the middle half of products list 75 mg to 500 mg, the median 185 mg.3,300 mg

Higher than 96% of 526 products listing fructo-oligosaccharides (median 185 mg).

Source: NIH ODS Dietary Supplement Label Database, label 213554 (entered February 26, 2020), version 9.4.0. See the label on DSLD. Amounts are what the maker printed; DSLD does not test products. Daily Values: the FDA's Daily Value page.

Is that a lot?

The rows in the top or bottom tenth of the products that list the same ingredient, and any above the adult upper limit at the most servings a day the directions give:

  • Its 3,300 mg of fructooligosaccharides (filed by NIH under fructo-oligosaccharides) is higher than 96% of the 526 fructo-oligosaccharides products that print an amount; 19 list more.

The NIH database records one serving a day from the label's directions; its % Daily Values are for adults and children 4 or more years of age. The directions as printed are further down this page.

The Tolerable Upper Intake Level is the most of a nutrient per day, from food, water and supplements together, that is likely to pose no risk for almost all adults (Institute of Medicine, 2011). It does not apply under medical supervision. This page compares labels; it is not medical advice.

Sources: amounts from the DSLD label; Daily Values from 21 CFR 101.9(c)(8)(iv); adult upper limits from the Institute of Medicine's DRI summary tables (2011). How positions are computed.

Which products have the closest formulas?

3 products list the very same ingredients; the nearest amounts come first.

Source: ingredient lists of every product's current label in DSLD (version 9.4.0); similarity weights each shared ingredient by how rare it is.

What does the label say about taking it?

Quoted from the label as DSLD transcribed it: the maker's words, including any claim about what the product does, which the FDA has not evaluated and PlainVitamins does not endorse.

Directions
Suggested Use: 1 rounded teaspoon daily, mixed in water or juice as desired.
Warnings
Note: If you are pregnant, may become pregnant, or breastfeeding, consult your health care professional before using this product.
Do not use if either tamper-evident seal is broken or missing.
Keep out of the reach of children.
Allergens and what it does not contain
Contains no yeast, dairy, egg, gluten, corn, soy or wheat. Contains no starch, preservatives, or artificial color, flavor or fragrance.
Storage
Store in a cool, dry place.

Source: label statements in DSLD label 213554.

How many labels does Fos have?

2 labels are on file under this name since February 26, 2020: other sizes, label designs and reformulations. The current one leads this page.

  1. Label 213555 Entered February 26, 2020 · off the market December 22, 2021 · 200 grams · UPC 0 21078 00578 0
  2. Label 213554 (current) Entered February 26, 2020 · on the market · 100 grams · UPC 0 21078 00577 3

DSLD also links this label to: FOS Powder (package size difference, same product).

Source: DSLD label entry and market events, version 9.4.0 (labels entered through September 25, 2025).

Who makes it?

The label names Source Naturals, Inc. (distributor), Santa Cruz, CA. All Source Naturals products.

Where next?