(this is the follow up to "How I Stopped Eating Food")
Edit July 2013: This was a prototype. While similar in spirit, the final soylent recipe differs in several ways and has been subjected to rigorous testing and expert evaluation. Also it tastes better.
There is precious little good data in nutrition science. Every study I've seen shows poor statistical methods, conflicts with other studies, or does not show statistically significant results, usually all three. It's a difficult field because there are simply too many variables and the parameters are difficult to control precisely. This is why diets are fads. I decided to ditch nutrition and focus on biology. The proportions in Soylent are closely based off of the recommendations of the Institute of Medicine (IOM), though I added a couple extras and changed a few based on my testing. Here is what my body needs.
Carbohydrates (400g): Any molecule consisting only of Carbon, Hydrogen, and Oxygen. Flour, corn, bread, rice, pasta, your cells don't care. What you need is D-Glucose. The Citric Acid Cycle metabolizes glucose and generates ATP, the cellular 'currency' for energy. Carbs can chain together and come in the form of monosaccharides (like fructose), disaccharides (table sugar), oligosaccharides, or polysaccharides, which are very long chains. Short chains get metabolized very quickly, leading to a 'sugar rush', and long chains can be difficult to digest. I use only oligosaccharides, like Maltodextrin, for Carbohydrates. This mechanism can also metabolize protein and fat, but the brain can only use Glucose for energy. In fact, the brain uses 25% of the body's glucose, though it accounts for only 2% of its weight.
Protein (120g): Protein is a very general term. What your body needs are 9 'essential' (meaning the body cannot produce it itself), amino acids: Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, and Valine. Eukaryotes use 21 different amino acids for protein synthesis. The human genome contains approximately 20,000 protein coding genes. It's a complex system. Without these essentials there are some proteins you will not be able to produce.
Fat (65g): Fat has gotten a bad rap. Without it you wouldn't be able to absorb some essential vitamins, like A, D, E, and K. Fats are triglycerides, and can be saturated or unsaturated, depending on the bonds within the carbon chain. Fat maintains healthy skin and hair, and cushions the body's organs. Some fats, though, like trans-saturated fats, are difficult for the body to metabolize, and have been linked to heart disease and obesity. I get all the fat I need, in nearly perfect proportion of saturated and unsaturated, and no trans fats, from olive oil.
Cholesterol(X): Cholesterol is used in cell membranes and intracellular transport. However, the body is able to synthesize it on its own and regulates the rate of production. So, even though the IOM mentions it I feel it's more of a maximum than a recommendation. Soylent has no cholesterol whatsoever.
Sodium(2.4g): You'll notice a lot of the elements the body needs are ions. Cells communicate with action potentials, electrical voltage differences which accumulate due to the presence of positive or negative ions. Sodium ions are used to regulate blood volume, blood pressure, pH, and osmotic equilibrium. Sodium and Chloride are conveniently found in table salt.
Potassium(3.5g): Potassium is important in neurological functioning, which is one reason it bothers me practically no one gets a full 3.5g / day. Raw Potassium is extremely reactive, so I use potassium gluconate, C6H11KO7.
Chloride(3.4g): Chloride is a negative ion, formed when Chlorine gets an extra electron. It's used in metabolism and overall pH balance.
Fiber(40g): Fiber is not digested by the body. It helps maintain a healthy digestive system. My digestive system is quite healthy as the only thing that it has to get rid of is the fiber itself.
Calcium(1g): Strong bones and teeth! Also used in muscle operation and the electrical system of the heart. Very important. I consume Calcium Carbonate, CaCO3
Iron(18mg): Iron is used by Hemoglobin in the blood to efficiently transport oxygen. Iron deficiency is one of the most common nutritional deficiencies. If you are a vegetarian I recommend taking a supplement. I dissolve iron chellate in fat separately before adding it to the mixture.
Phosphorous(1g): Part of the structural framework for DNA and RNA. I use monosodium phosphate.
Iodine(150ug): Constituent of Thyroid Hormones, which regulate basic metabolic rate through gene transcription.
Magnesium(400mg): Another ion, used by many enzymes to catalyze reactions. Be careful, magnesium overdose is very unpleasant.
Zinc(15mg): Used by enzymes in transcription factors, which control the expression of select genes.
Selenium(70ug): Used in some amino acids and the Thyroid gland. Careful, can be toxic in large doses.
Copper(2mg): Used in electron and oxygen transport.
Manganese(2mg): Similar to selenium, used as a cofactor in many enzymes.
Chromium(120ug): Occurs in trace amounts in many foods. Though no certain biological role has been found, there have been reports of chromium deficiency. Just being safe here, may be fine without it, though.
Molybdenum(75ug): Used in the active site of many enzymes. Interesting fact: a shortage of molybdenum held back eukaryote evolution for 2 billion years. Make sure you get your molybdenum, and continue evolving.
Vitamin A(5000IU): Used by the retina of the eye to produce a metabolite necessary for both low-light and color sensitivity.
Vitamin B6(2mg): Or, pyrodoxil phosphate, is a coenzyme for many reactions and macronutrient metabolism.
Vitamin B12(6ug): Key to the normal functioning of the brain and nervous system. Like iron, difficult to obtain from plants so a supplement is suggested for vegetarians.
Vitamin C(60mg): Or, ascorbate, is a reducing agent in many enzymatic and some non-enzymatic reactions. Don't want to get scurvy.
Vitamin D(400IU): Needed for the internal absorption of calcium and phosphate. Can be synthesized by the body from cholesterol given enough sunlight, but is essential in most people.
Vitamin E(30IU): Several functions including antioxidation, gene expression, and neurological function.
Vitamin K(80ug): Post-translational modification. Once a protein is transcribed, it folds (which is a very important problem we don't understand well) and modified by factors such as Vitamin K which affect its final utility.
Thiamin(1.5mg): Used in thyamine pyrophosphate, a coenyzme in the catabolism of sugars.
Riboflavin(1.7mg): Required by a class of proteins called 'flavoproteins'. It's used in the cofactors (non-protein substances that bind to proteins) FAD and FMN.
Niacin(20mg): Niacin binds to and stimulates a certain membrane receptor, GPR109A, which inhibits fat breakdown in adipose (stored fat) tissue. This decreases the amount of free fatty acids in your blood.
Folate(400ug): Folate itself is not used by the body, but its derivative tetrahydrofolate, and a few others, are used in DNA synthesis and repair.
Biotin(300ug): Another coenzyme, used in the synthesis of a few macronutrients.
Panthothenic Acid(10mg): Used to synthesize coenyzme-A (which itself is used in the synthesis and oxidization of fatty acids), as well as metabolism.
Extras not considered essential:
Lycopene(500ug): Essential in some plants for photosynthesis, it is abundant in red plants like tomatoes and carrots. Lycopene is an effective antioxidant and there is preliminary evidence it has an effect on cardiovascular health, diabetes, cancer, and others. Also, not very scientifc, but the males in my family have always loved tomatoes. I wonder if this is because lycopene has an unusually positive effect given our genetics. The only other nutrients in tomatoes are Vitamin A and C, which I get plenty of.
Omega-3 Fatty Acids(750mg): Humans cannot synthesize these fatty acids, and though links with cancer have been largely debunked, there is limited evidence consumption of these substances improve cardiovascular health and inhibit cognitive aging.
Ginseng(50ug): Used in old folk remedies, limited evidence suggest a link with sexual health and lower fatigue.
Gingko Biloba(100ug): Consumed since antiquity in China and Japan, has limited evidence of positive effect on working memory and focus.
Lutein(500ug): A rather small study found that Lutein improves visual function and can inhibit macular degeneration. There is stronger evidence Lutein is linked to the pigmentation of the eye.
Alpha Carotene(140ug): A single study linked this with lower risk of mortality from heart disease and cancer. Couldn't hurt.
Vanadium(100ug): Limited evidence has a beneficial affect on glucose control.
The body is a complex machine. There are a lot of substances and chemicals required for it's optimal operation. However, it is also extremely robust. Many people aren't getting the recommended amount of any of these substances, but the body is able to compensate via complex regulatory systems. This hurts in the long run, though. In fact, turning food in to energy is the primary process that ages the body. By giving it only what it needs, and nothing it doesn't, I am optimistic about the long term effects. The short term effects are already clear.
If you want to make Soylent for yourself, be very careful. We're not making pie here. It's a lot easier to overdose or underdose with the raw elemental form than it is with food. It took me a while to arrange sources for all of these substances, as well. You can get many micronutrients from a simple multivitamin, but their contents vary widely. For others such as K, P, Ca, Mg, check your local lab supply store or university, making sure they are regulated for human consumption. I actually got a lot of mileage out of brewing stores as well.
I am reticent to provide exact brand names and instructions because I am not fully convinced of the diet's safety for a physiology different than mine. What if I missed something that's essential for someone of a different race or age group? Also, the cost is low but some of the ingredients are hard to find and/or must be purchased in bulk which can be an investment, and some of my suppliers are quite small and would have their stock depleted if many people rushed to purchase the exact same item I did. I think it makes more sense to test this more thoroughly, and then produce it at scale.
So…I'll just ship you some of my batch. If you are willing to consume exclusively soylent, and get a CBC, chem panel, and lipid blood test before and after the week and share your results with me it's on the house. Bonus points for getting a psych evaluation before and after. The brain is an organ. I can ship it worldwide but it would be nice if you were in San Francisco so we can meet in person.
Update: Choline is included of course