Z-STACKZelenko Labs, built on the legacy of Dr. Vladimir Zelenko, creates products with purpose, precision, and integrity. Every formulation is made with high-quality ingredients and consistent standards, so you can feel confident in what you’re using. Thoughtful, reliable, and principled — Zelenko Labs products are made for people who care about quality.Our All American customer service team is here to help Monday through Friday, 9 AM to 5 PM EST — just give us a call at 1-800-ZELENKO (1-800-935-3656) or email our team at [email protected]
Z-STACK (zstacklife.com) has 95 customer reviews on Five Star Index, with an average rating of 4.1 out of 5.
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Personal Care · Orlando, Florida
Excellent
Personal Care · Grants Pass, Oregon
Excellent
Personal Care · Great Neck, NY
Excellent
Personal Care · Costa Mesa, California
Excellent
Showing 71 reviews with 5 stars · Clear filters
Marlene R.
I started taking Z Stack shortly after COVID hit. Haven't been sick. Yes, I didn't get COVID either. My immune system is thanking me. I also have started (a few months ago) talking CALM. It's enhanced my use of St Johns' Wort and a prescription med for anxiety. I would recommend both supplements to anyone asking about them.
Response from Z-STACKApr 14, 2026
Thankyou Marlene!
RHS
Great products and customer service.
Response from Z-STACKApr 2, 2026
Thank you!! :)
Timothy H.
I’ve been using Z stack for going on six years ever since Covid started and it has been my go to immune booster. I use the Z night now to get a restful sleep and they Zelin go laps is my trust is Source for health protection.
Response from Z-STACKMar 30, 2026
Thank you Timothy!
Candace A L.
A+ product and excellent customer service. I highly recommend Zelenko Labs.
Response from Z-STACKMar 30, 2026
Thank you Candace!
Jordan P.
Zstack is the best supplement my husband and I have had so far. We’ve never been sick since we started to use it. It has every ingredient in it that our body needs. Unfortunately we’re paying a postage as high as for one bottle of Zstack. This is the only reason we have to stop buying it. For this reason being said we’re not happy that nothing can be done in that direction. Although we would recommend Zstack to anyone.
Response from Z-STACKMar 25, 2026
Thank you so much for your kind words Jordan! We will work on the cost of International Shipping. If you ever stop by, in the USA we have free domestic shipping.
Juanita
I have had a subscription for Z-Stack for over 4 years. After covid I was looking for a good vitamin. I knew I was low in Vitamin D, and I wanted a vitamin that would help with my low Vitamin D levels. I started listening to Dr. Zelenko and decided to try the Z-Stack. After taking Z-Stack for several months, I had bloodwork done and my Vitamin D levels were better than they ever have been and continue to be at a healthy level every year and that is why I continue my subscription each year. The vitamins work. I am confident these vitamins help me stay healthy. You will not be disappointed with these vitamins.
Response from Z-STACKMar 16, 2026
Thank you Juanita, I love to hear stories like yours!
Linda W.
Our family has been using Zelenko products since their inception. My grands especially like the strawberry flavored gummies now ZFlu. Thank you for keeping Dr. Zelenko’s legacy alive and well!
Response from Z-STACKMar 16, 2026
Thank you Linda!
Rhonda D.
I have been using your products for years. Very happy with the product and services received.
Response from Z-STACKMar 11, 2026
Thank you Rhonda!