Proteins are vital to the proper functioning of the human body. When you think of protein, you probably think of your muscles and people like bodybuilders drinking protein shakes to grow them. And while you’d be correct — that’s just one of the ways we need and use protein!

Protein is responsible for much of the structure, function and regulation of the entire human body. Everything from muscle growth, to immune response, to coordination of hormones, and organ function relies on protein.

It’s also not enough to just eat any protein. There are merits and drawbacks depending on the source of protein, which have to do with each source’s composition. “Protein” is a bit of a catchall for a type of molecule found in your body and in nature. It’s not certain, but we think there are over 20,000 different proteins in our body alone.

What is a protein?

Proteins are complex structures made up of smaller components known as amino acids. Amino acids are organic compounds typically consisting of elements like Nitrogen, Carbon, Hydrogen, and a few more. There are over 500 known, naturally occurring amino acids in the world, but only 20 of these are combined to make all the proteins in the human body.

Our bodies are incredible. We are able to synthesize 11 out of the 20 amino acids we can make proteins with, using just the systems present inside ourselves. However, that means the other 9, known as “essential amino acids”, cannot be synthesized and need to be taken in through diet.

These essential amino acids are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. It’s not important to memorize these, but it is important to know that there are ideal quantities and ratios of these amino acids for our optimal function. After all, we use these essential amino acids to create the other 11 “non-essential amino acids”, and then, with all 20 amino acids, make all the protein in our body.

These ratios and quantities are also different across different stages of our life cycle. Some of these “essential amino acids” are conditionally essential, like in times of stress or disease or early stages of growth. For example, in infants and children there are higher requirements of ratios of protein gram per kilogram of body weight per day, or g/kg/day.

How much should I have?

That’s actually a highly individual question, which can vary strongly from person to person. There are many reasons for this including genetics, gut health, level of exercise, injury, and more. However society practically needs to have some metric for recommendation, and scientists and nutritionists have established methods to produce ranges and recommended daily intake for the population generally.

The most frequently accepted recommended intake is 0.8g/kg/day as a baseline for adults. This is found using sample populations taken from society and a method known as the Nitrogen Balance Method. This number takes into account all the samples taken from the population and provides a number using statistics and regressions that is meant to consistently represent the center.

The Nitrogen Balance Method measures the amount of nitrogen taken in against the amount of nitrogen excreted. Nitrogen being a fundamental component of amino acids and protein. While this method is the most theoretically satisfactory and practical for measuring populations, it has been criticized for underestimating protein requirements. Reasons include the tendency to overestimate intake and underestimate excretion, miscellaneous losses of nitrogen which are unaccountable, and comparison to several other methods, where the Nitrogen Balance Method produces a result significantly lower than of other methods, which each produce results similar to the others. Additionally, the quality of protein matters, since these Nitrogen Balance Method studies were conducted using high quality protein, but low quality proteins may require higher quantities for the same effect.

According to this method, a daily recommended intake is .8g/kg/day. However studies for healthy adults have shown no adverse effects where protein intake is measured as a % of calories up to 35% of dietary composition. For a 2000 calorie diet, that would mean 700 calories from protein, or 175g per day. That’s also not to say that 35% is the upper limit, as no upper limit has been established for daily protein intake. This was only a metric established to provide parameters for the studies which have been conducted in the past.

To summarize, current recommended daily intake is .8g/kg/day. This recommendation is intended to represent a center statistic for all samples(people studied) within a population, and it is the recommendation for high quality sources of protein. Even using the Nitrogen Balance Method, individual protein needs vary person to person according to genes, lifestyle, and other factors.

Does it matter what type? What is a high quality protein?

It depends on how you look at it. Remember those 9 essential amino acids? Those matter. Where you get them is less important, considering amino acid intake alone. Setting aside conversations of cholesterol and other considerations (which are still important, but a topic for another day), the primary issue for protein is getting enough of those 9 essential amino acids. Animal sources of protein have all 9 essential amino acids as a rule. Plant sources typically do not. There are some plants which do, like soy, but eating too much soy has important consequences, which also aren’t the topic of today. Pea protein for example, which is a common ingredient in most plant-based protein supplements, does not have the correct levels of the essential amino acids needed for your body. Plant proteins are also more difficult to digest than animal proteins as a general rule.

Luckily, society has established a system for ranking proteins by their essential amino acids and digestibility, known as the PDCAAS system. PDCAAS stands for protein digestibility-corrected amino acid score, and ranks on a scale up to 1, where 1 is an ideal protein source. The figure below shows a chart of the PDCAAS for common foods (source).

What all this means is that if you’re trying to reach your .8g/kg/day, it’s important to factor in the quality and digestibility of that source. It’s also not as simple as using algebra and a PDCAAS score to simply eat more of that one source. For vegans particularly, it’s important to balance your different protein sources to ensure you’re meeting the minimum protein requirements across a proper ratio. Cultures have been doing this for thousands of years though, for example the pairing of a diet of beans and rice. Beans are high in methionine and low in lysine, while rice is high in lysine and low in methionine.

Another way to consume protein is through the use of protein supplements. As you can see from the chart above, whey and soy protein have a PDCAAS score of 1. This makes them excellent candidates for receiving all 9 essential amino acids. However there are other issues to this, since whey comes from dairy and typically has lactose in at least trace amounts and can be ethically objectionable, and soy has compounds which exhibit estrogenic properties and should only be consumed in moderation. Choosing between the high social and environmental costs with the more nutritious animal proteins or saving the planet but with a more difficult to digest and less-bioavailable plant protein is a problem.

Aaaand here it is, you knew it was coming.

Introducing… Space Milk!!

Space Milk, an innovative new company, is launching the world’s first vegan, hypoallergenic protein supplement with a PDCAAS score of 1 that’s also clean. It does so by using the first of its kind ‘Alternative Protein’ which is neither plant nor animal sourced. The protein is technically yeast-based, but new technology and all-water separation and filtration allows Space Milk to be free of all yeast derivatives which produce flavor or allergens. That also means it tastes better than whey and plant-based proteins too!

Space Milk sees this technology as a true solution to our consumption problems, since food demands are set to double by 2050, and costs to the planet are already too high today. Space Milk is better for the planet than plant-based, and better for you than animal-based proteins. The best of both worlds. Did we mention it tastes better–that technically makes it out-of-this world, right?

Which is a convenient segue into the other application we see: space food. By growing yeast in tanks, separating its components, and recycling the materials, we believe that products like ours are the origin for the future of nutrition in space and long-term space exploration.

Want to learn more? Head over to www.spacemilk.com and see what it’s all about.

Have even more questions? Reach us directly at contact@spacemilk.com and we’ll be happy to help!