PlainVitamins

I-Tryptophan

by Isotonix · powder · 3.5 oz.

  • On the market (NIH)
  • DSLD label 29574
  • Serving 3.3 to 6.6 g (1-2 capfuls); amounts per 3.3 g
  • 30 servings

I-Tryptophan by Isotonix lists 6 ingredients, 6 with an amount per serving of 3.3 g, such as 850 IU of vitamin A, 75 mg of vitamin C, 20 mg of niacin and 4 mg of vitamin B6, beside 3 Nutrition Facts rows (calories, fat and the like). Its current label entered the NIH Dietary Supplement Label Database on January 24, 2014.

What is in I-Tryptophan?

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).

I-Tryptophan: Supplement Facts rows against the market (DSLD label 29574, January 2026 release)
IngredientAmount% DVAmong products listing it
Calories5 Calories
Total Carbohydrates1 g1%Carbohydrate in I-Tryptophan against 21,979 products1 g per serving; the middle half of products list 1 g to 6 g, the median 3 g.1 g

74% of 21,979 products listing carbohydrate give more (median 3 g).

Sugar1 gSugar in I-Tryptophan against 11,807 products1 g per serving; the middle half of products list 1 g to 4 g, the median 2 g.1 g

69% of 11,807 products listing sugar give more (median 2 g).

Vitamin Aas Beta-Carotene850 IU17%Vitamin A in I-Tryptophan against 5,772 products850 IU per serving; the middle half of products list 2,000 IU to 5,000 IU, the median 4,000 IU.850 IU

88% of 5,772 products listing vitamin A give more (median 4,000 IU).

Vitamin Cas Ascorbic Acid75 mg125%Vitamin C in I-Tryptophan against 18,583 products75 mg per serving; the middle half of products list 60 mg to 270 mg, the median 100 mg.DV 90 mgUL 2,000 mg75 mg

62% of 18,583 products listing vitamin C give more (median 100 mg).

Niacin20 mg100%Niacin in I-Tryptophan against 12,413 products20 mg per serving; the middle half of products list 13.2 mg to 48 mg, the median 20 mg.DV 16 mgUL 35 mg20 mg

46% of 12,413 products listing niacin give more (median 20 mg).

Vitamin B6as Pyridoxine Hydrochloride4 mg200%Vitamin B6 in I-Tryptophan against 15,277 products4 mg per serving; the middle half of products list 2 mg to 20 mg, the median 6 mg.DV 1.7 mgUL 100 mg4 mg

59% of 15,277 products listing vitamin B6 give more (median 6 mg).

Sodiumas Sodium Bicarbonate40 mg2%Sodium in I-Tryptophan against 14,514 products40 mg per serving; the middle half of products list 15 mg to 142 mg, the median 55 mg.40 mg

56% of 14,514 products listing sodium give more (median 55 mg).

Potassiumas Potassium Bicarbonate160 mg5%Potassium in I-Tryptophan against 11,614 products160 mg per serving; the middle half of products list 50 mg to 190 mg, the median 99 mg.DV 4,700 mg160 mg

Higher than 69% of 11,614 products listing potassium (median 99 mg).

L-Tryptophan500 mgTryptophan in I-Tryptophan against 605 products500 mg per serving; the middle half of products list 55 mg to 471 mg, the median 123 mg.500 mg

Higher than 76% of 605 products listing tryptophan (median 123 mg).

Source: NIH ODS Dietary Supplement Label Database, label 29574 (entered January 24, 2014), 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?

Every amount on this label with a position sits within the middle 80% of the products that list the same ingredient.

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?

The products whose ingredient lists overlap most with I-Tryptophan's, rare ingredients counting for more.

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
Directions for adult use: For sleep support: Take 1-2 servings 30 minutes prior to bedtime. Pour 1-2 level, white bottle capfuls of powder into the overcap. Add 2 fl. oz/60ml (line on the overcap indicates 2 fl. oz/60mL) of water per capful of powder and stir.
For mood enhancement: Pour 1 level, white bottle capful of powder into the overcap. Add water to the line on the overcap (2 fl. oz./60 mL) and stir.
Maximum absorption occurs when taken on an empty stomach. As a dietary supplement, take one or two times daily, or as directed by your healthcare provider.
Warnings
Do not use if safety seal is broken or missing.
Warning: If you are currently taking monoamine oxidase inhibitors (MAOI) or other antidepressants such as Zoloft or Paxil, psychoactive or tranquilizing drugs such as Kllonopin or Vallium, or pain medications such as Demerol or Ultram, you should consult your healthcare provider before using this product. If you are using any other prescription drugs or have an ongoing medical condition, you should consult your healthcare provider before using this product. Take this supplement separately from prescription drugs. Women who are pregnant or breastfeeding should not use this product.
Do not drive or operate heavy machinery until you know how this product can affect you, as drowsiness may occur.
KEEP OUT OF REACH OF CHILDREN.
Storage
Store in a cool, dry place.

Source: label statements in DSLD label 29574.

What else is on the label?

Other ingredients: Fructose, Citric Acid, Orange juice powder, Malic Acid, Orange flavor, Mango flavor, Rebaudioside A, Silicon Dioxide, Lo Han (fruit) extract.

How many labels does I-Tryptophan have?

One label is on file, entered on January 24, 2014.

  1. Label 29574 (current) Entered January 24, 2014 · on the market · 3.5 oz.

DSLD also links this label to: l-Tryptophan (image 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 Market America, Inc. (distributor), Greensboro, NC. All Isotonix products.

Where next?