Why Soy Protein?

Soy protein isolate was chosen due to its bioavailability, meaning that it is easily absorbed by the digestive system. Using a protein digestibility-corrected amino acid score (PDCAAS), which gauges how well certain proteins can be digested, soy protein isolate was found to be the best with a score of 1.0. Additionally, soy protein isolate has a smooth, consistent texture which creates the optimal flavor profile. During our testing, we found that alternative proteins lacked both of these benefits.

Why is soy protein isolate the right choice?

Whey, casein and egg white - All three of these have a PDCAAS score equal to soy protein isolate but have other drawbacks. These options are derived from animal products, so they inherently use more resources to be produced than plant based proteins.

Hemp - Hemp has a PDCAAS score of 0.46, meaning it is less bioavailable than soy. It also has a rough texture and odd taste.

Pea - Similar to hemp, pea protein has a lower PDCAAS score of 0.69. It also has a strong flavor and is often gritty, slimy and unpleasant to drink.

Rice - Rice has a PDCAAS score of 0.47 and has a rough, silty, occasionally sandy feel due to the brown rice protein. The other major downside is the amount of heavy metals that rice naturally picks up from the ground. Lead, arsenic, cadmium and others were a major concern for a food that is designed to act as a daily meal.


A very small population is allergic to the different types of protein available on the market today, including soy protein isolate. We recommend that you check with a doctor to make sure you are not allergic to soy before making Soylent a daily choice.

We also want to remind all of our customers that our community has a massive DIY movement behind it. They are constantly playing around with the formula to adapt it for their individual needs.

Does soy protein isolate cause hormonal issues?

All hormonal issues related to soy protein isolate have been based off clinical trials and meta-studies with results that are inconsistent at best. A simple search will pull up studies that show positive and negative results. The problem is science is an iterative process, meaning it takes many passes and studies to confirm something as fact. If you are worried about having a reaction to soy protein isolate, look through your family medical history to see if there is any sensitivity or consult your doctor.

We encourage our users to keep evaluating our products and suggesting alternatives.