Customize Your Shopping Experience!

Please select the destination country, language, and currency you prefer.

Available Shipping Methods
Available Payment Methods
Added to Cart
Combo Discount:
View/Edit Cart Checkout
Cart Total:
Customers Also Bought:

Source Naturals, L-Phenylalanine, 500 mg, 100 Tablets

By Source Naturals

Our Price:
You Save:
$5.97 (46%)
  • Volume Discount
  • Buy 4+
    Save 5%
Earn 10% Loyalty Credit ?

This product is already in your Wish List.

View Wish List

This product is now in your Wish List.

In Stock
  • Product Code: SNS-00161
  • UPC Code: 021078001614
  • Package Quantity: 100 Tablets
  • Dimensions: 2 x 2 x 3.5 in, 0.2 lbs (0.09 kg)
Bundle Offer
Save $6.00 when you purchase these items today for only $9.96


Combo Discount:



- $6.00


Product Overview

  • Dietary Supplement
  • Free Form
  • An Essential Amino Acid

L-Phenylalanine, an essential amino acid, is a precursor of the amino acid tyrosine and a whole series of neurotransmitters and hormones. Phenylalanine is first converted to tyrosine, which becomes L-dopa, which converts to norepinephrine, a key neurotransmitter and an adrenal hormone. L-Phenylalanine is also a direct precursor of PEA (phenylethylamine), another important neurotransmitter.

Suggested Use

1 to 2 tablets daily.

Other Ingredients

Dibasic calcium phosphate, stearic acid, colloidal silicon dioxide, modified cellulose gum, and magnesium stearate.

Suitable for vegetarians and Hypoallergenic: contains no yeast, dairy, egg, gluten, corn, soy or wheat. Contains no sugar, starch, salt, preservatives, or artificial color, flavor or fragrance.


Do not use if either tamper-evident seal is broken or missing. Keep out of the reach of children.

Contains phenylalanine. Not to be used by phenylketonurics, women who are pregnant, may become pregnant, or breastfeeding, or with antidepressant drugs such as MAOIs or SSRIs. If you have chronic high blood pressure, take after meals and/or consult your health care professional.

Visit Manufacturer's Website
Supplement Facts
Serving Size: 2 Tablets
Servings Per Container: 50
  Amount Per Serving %DV
Calcium 99 mg 10%
L-Phenylalanine 1 g
†Daily Value not established

iHerb Customer Reviews

5 Stars
4 Stars
3 Stars
2 Stars
1 Stars

Good, but I prefer tyrosine

Posted by justkickingit on Aug 31, 2012

This is just a bit too activating for me, I get a light headache from it. Tyrosine works better for me. Caution if you have high anxiety or are prone to mania, seems to disrupt us a little more.

Was this review helpful to you?

3 people found the following review helpful

think this is a great appetite suppressant

Posted by lisofby on Aug 27, 2012

this seems to be what made me not want dinner over the summer. i would force myself to take amazing grass amazing meal. for the nutrients, but no appetite!

Was this review helpful to you?

2 people found the following review helpful

Excellent product

Posted by Reviewer2022209 on Oct 06, 2010

Phenylalanine is great for mood and muscle pain from fibromyalgia. I bought this because we like Source Naturals, but I realized it was actually the "DL" phenylalanine that I needed. I combine 1500 mgs. DL phenylalanine with 1500 mgs of tryptophan at night and sleep absolutely wonderful. I wake with only minimal pain from fibromyalgia. Really love it for that reason.

Was this review helpful to you?

2 people found the following review helpful

Good prize

Posted by willowman on Jul 26, 2012

I like this product because it has so good price it is very hard to find l-phenylalanine to this price or i havent

Was this review helpful to you?

2 people found the following review helpful

Dogs diet

Posted by Reviewer1550954 on Jan 29, 2008

My vet suggested to add phenylalanine to dogs food. I chose your product and so far the dog seems to have more energy.

Was this review helpful to you?

1 person found the following review helpful

See All Reviews