Soy Protein

We recently announced our new Powder formula, Coffiest, and Soylent Bar. While we were very excited for these products, there were a number of people that were left scratching their heads. The number one question was: Why soy protein?

We covered this issue briefly when we announced Soylent Drink, but we know that, “it tastes good,” isn’t reason enough for our customers. So let’s explore all the common concerns soy raises, look at our other options, and see why soy was the #1 contender.

Alternative Protein Options

We looked into a lot of protein options for Soylent products, as not all proteins are created equal. Soy happens to be extremely bioavailable, with a PDCAAS score of 1.0, and is also smooth, tasty and uses few resources to produce. Here are a few of the other options we explored, and why we didn’t choose to use them in Soylent.

Whey, Casein, & Egg White - All three of these have a PDCAAS score equal to soy, but have other draw-backs. As all three of these options are derived from animal products, they inherently use more resources to produce than plant based proteins. This is because producing animal products includes the footprint of the crops used to feed the animals, the water and land the animals require, and the associated emissions. With this in mind, we can’t reasonably call ourselves a sustainable company while including these ingredients.

In addition, all three are also on the list of common allergens, and including them would only exclude a new group of people from Soylent.

Hemp - Hemp has a PDCAAS score of 0.46, meaning it is less bioavailable than soy. Taste, texture and cost are also barriers to including hemp. While it may be an option in the future, current hemp protein blends just can’t make a smooth, neutral meal the way that soy can. A switch to hemp would also mean a drastic increase in cost, which would go against our mission of complete, affordable nutrition.

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 - Our original formulas included brown rice protein and oat protein. This offered a complement of Amino Acids, as rice has a PDCAAS score of 0.47 and oats/ cereals are about 0.59. Anyone that drank Soylent 1.0-1.5 will be familiar with the slightly gritty, silty, occasionally sandy feel of brown rice protein. Despite choosing one of the finest blend options, this texture remained. The other major downside was 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 staple meal. While not dangerous in the short term, we wanted to make a product we knew people could eat for their whole lives without worry. Soy is therefore a great alternative because of it’s smooth mouth feel, and lower levels of contaminants.


When it comes to staple foods, allergies will always be a concern.

There are plenty of foods that can cause allergic reactions, but soy is one of the 8 most common allergens in the United States. This means that all Soylent products are inedible for a small portion of people. Unfortunately, alternatives aren’t any better, as 3 of the potential alternatives (whey, casein and eggs) and are also on that list. This means that any choice will unfortunately alienate some users.

We know that this is very frustrating for people that have changed their lifestyles and habits with Soylent. We want you to know that this decision wasn’t made lightly, and that the positives of soy were too apparent to deny. We can assure you that we’re working on new, novel concepts and one day hope to make blends that everyone can enjoy. Until then, we’re open to suggestions.

Hormonal Effects

After allergies, the next largest concern raised about soy is that it “turns men into women” and “gives women breast cancer”. The main issue with these claims is that nutritional research, including both clinical trials and meta-studies, is wishy washy at best. There are studies showing protective and antagonistic results for both breast cancer and prostate cancer, some show lowered testosterone and sperm counts in men, while others show no change, and the list goes on and on. If your head isn’t spinning by the end of it, please, check our job postings.

The takeaway for us is this: so far soy seems safe, especially when compared to other proteins whose consumption is much more closely linked to cancer.

That doesn’t mean that soy is appropriate for everyone. If you have concerns about soy and your health we recommend consulting your doctor and going over your family’s medical history. Even the most common staple foods can cause problems for some people, so we encourage you to take initiative to find out what is right for you. For customers interested in the isoflavone (a compound similar to estrogen) levels of the soy in Soylent, one serving of Soylent Drink has approximately 52 mg of isoflavones and one serving of Soylent Powder has 53 mg. Soylent Bar and Coffiest have not yet been tested, but will be shortly. 

Environmental Concerns

Soy grown in the U.S. is nearly always genetically engineered, and soy grown in other areas of the world is often linked to clear cutting and deforestation. The link to forest and habitat destruction is one of the reasons why we purchase soy grown here in the U.S. (though if we chose not to buy U.S. grown soy, it’s worth noting that nearly all of the soy grown in clear cut areas is used for animal feed, and is not used for human consumption).

The GMO concern is multifaceted. Not only are some people concerned that GE crops themselves are dangerous, but then there are concerns over the pesticides chosen, effects of mono-crop farms, and the general concern that the companies making them aren’t the most moral and to buy a GMO is to support them. You can read all about our take on Genetic Engineering here.

Our support for GE technology also doesn’t mean that we support everything that the industry does. We just believe that food can be grown in more than one way and it’s worth exploring. This is why we support small cellular agriculture start-ups and have chosen to be vocal on this subject.

And the winner is…

Soy! At least for now. We encourage our users to keep evaluating our products and suggesting alternatives. Hopefully this offers some insight into our protein source, so keep those questions coming!


To learn more about the design process of Soylent, read the Soylent Approach To Nutrition.



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