All right, I’m going to do some brief searches to figure out how much we (humanity) know about how necessary some of the nutrients you’ve listed are. Phosphorus, potassium, and sulfur are all included in official Soylent and are tracked on the DIY site as well, so most people will get enough of those. From the UK NHS list, that leaves beta-carotene, boron, cobalt, nickel, and silicon.
Beta-carotene is a precursor to vitamin A. The way I understand it, the truly useful forms of vitamin A are retinol, retinal, and retinoic acid. The group of chemicals known as carotenes (of which beta-carotene is a member) are useful because they can be converted into the more useful retin-prefixed chemicals. In Soylent, vitamin A is provided as retinyl palmitate, a synthetic form of retinol. Adding beta-carotene to Soylent wouldn’t help in the vitamin A sense, but there still could be reasons to supplement it directly. Some of the most highly cited articles I’ve seen in my brief search are:
Lack of Effect of Long-Term Supplementation with Beta Carotene on the Incidence of Malignant Neoplasms and Cardiovascular Disease. Prior to this large, long-term study, there was some reason to believe that supplementing beta-carotene would lower risks of cancer and cardiovascular disease. However, this 12-year study found no difference in any sort of mortality between people who took beta-carotene regularly and those who instead had a placebo.
Effects of a Combination of Beta Carotene and Vitamin A on Lung Cancer and Cardiovascular Disease. This 4-year study compared the effects of retinol, beta-carotene, retinol+beta-carotene, and placebo supplementation on mortality rates, especially looking at lung cancer in smokers, non-smokers, and those exposed to asbestos. They found that beta-carotene and retinol actually increased the chance of lung cancer or cardiovascular disease. The first study I listed actually commented on this one, saying their results did not show this increase in risk.
There are some studies showing that an antioxidant blend of vitamin C, vitamin A, zinc, and beta-carotene can reduce the risk of age-related macular degeneration (vision loss), but I haven’t found any studies which show that beta-carotene itself is responsible for the improvement. I’m seeing insufficient evidence all around to really support the idea of supplementing with beta-carotene.
Boron seems to have a good amount of evidence for it being an essential nutrient for mammals (such as ourselves). It is not yet well established how much we need, but rat and pig studies have shown that deficiencies can occur, but can be fixed by supplementing an extremely low amount of boron (They had to filter the dust from the air in order to induce any sort of deficiency in rats). I think it’s estimated that a standard diet gives us 2-4mg of boron per day, and extrapolating from the animal studies would give us an approximate requirement on the order of µg. Considering boron is known to be an essential nutrient for plants, and we’ve got hundreds of grams of oat flour per day in Soylent, I’m guessing we’re getting enough just from that. I’m also reading that boron may be found in people’s tap water, which may be enough as well. Moral of the story here is that it’s probably necessary in tiny amounts, Soylent probably contains it, and nobody really knows how much we need in our food.
Some links for the curious:
A 20 year old survey of studies showing boron is important to brain functionality.
A more recent survey with evidence that boron is truly essential for human diets. It’s behind a paywall and I’m not on campus, so I can’t comment much more on that.
Cobalt is known to be an essential nutrient for animals. From what I’ve found, there haven’t been many (any?) studies on cobalt supplementation in humans, and limited studies on cobalt supplementation in animals. The only thing I’ve found that we know cobalt is useful for is in synthesizing vitamin B12. Farm animals get most of their cobalt from ingested soil, but we humans get it from a variety of dietary sources. If B12 is the only thing cobalt is needed for, then Soylent users don’t have to worry: B12 is provided in the right amounts. It is also worth noting that cobalt poisoning is a big concern, the classic example being cobalt used to stabilize beer foam causing serious problems in heavy drinkers (See here; paywall). Moral of the story here is that the only thing we know cobalt is used for is supplemented directly in Soylent, and researchers don’t seem to care enough to perform studies on its supplementation.
Nickel seems to be not important in human diets, but may be essential for some microorganisms living in our guts. I should note that it seems significantly more research has been done on the harmful effects of nickel than the beneficial. People worry about nickel from cooking things in stainless steel pots, nickel content in euro coins, the toxicity of nickel sulfide fumes, and how nickel released from a volcanic explosion fed a pathogen which contributed to the Permian–Triassic extinction event. Of course, these are mostly not about dietary nickel, but this at least would indicate to me that nobody has thought to themselves “Aha, I think nickel would be important for humans in this case; let’s do some research.” I’ve found some reason to believe that the large amount of oats in Soylent provide more than enough nickel for whatever we might use it for.
It’s more interesting to consider its uses for gut bacteria. We’ve only recently come to understand the real importance of the gut-brain axis, so we don’t know much about what we need to feed our gut bugs to make them happy.
Silicon seems like it might be important in bone formation. This study seems to show positive correlation between silicon intake and bone mineral density. Luckily for us, oats are known to be particularly high in silicon (425mg/100g). I haven’t written much here, but I don’t feel like there’s much more to say. We still don’t really know much about the uses of dietary silicon, but bone density seems like a good start, and Soylent’s got plenty of silicon for that.
Other notes: The USA has done a pretty good job establishing the DRI for all sorts of things. Refer to this and, more generally, this, for a lot of good info. Sadly, it’s getting a little out of date.
@derrick_farnell’s arguments fall into three categories: 1) Soylent is missing ingredients X, Y, and Z, which may be important, 2) Soylent may be missing essential ingredients that we don’t yet know are important, and 3) Soylent may be missing some non-essential nutrients which still provide important health benefits. Claim 1 was somewhat adequately supported by the UK NHS link, though if he wanted to go above and beyond, it would have been nice for him to do some research of his own first. I hope I’ve addressed some of those concerns. Claim 2 is pretty much unsupported, but more interesting because it’s sort of meta. How do we prove that our knowledge is incomplete? How do we prove that we know everything there is the know about a topic? Who should have the burden of proof between these two?
It’s hard to gauge exactly how much about nutrition we do know. I believe we can be fairly certain that we have identified everything that is truly essential. For an excellent example of this, refer back to the US DRI reports. Here, they’ve gone over every nutrient that they had sufficient reasoning to assume may be possibly essential, and done a meta-analysis for each. There are even other nutrients in the reports which they find to be non-essential or altogether useless. The probability that they’re missing actually essential nutrients in a report like this is very, very low. Furthermore, this is used as the basis for the ideal modern diet. If there are deficiencies in the DRI, then anybody following a “healthy” diet will encounter them, and I imagine widespread deficiency symptoms from people on the ideal diet would not go unnoticed.
To support Claim 3 for a bit, the big topics that we certainly don’t understand in nutrition are phytonutrient interactions and gut microbiome health. There are no diets in the world which can properly account for these factors right now, but luckily, they are not essential for our survival. They can definitely affect long-term cancer rates, mental health, and definitely GI issues, at least. If you think your current diet (or any “healthy” diet) properly optimizes these factors, you’re mistaken. Are the women in your life eating mushrooms and drinking green tea on a daily basis? If not, they’re much more at risk of breast cancer. Ever enjoy meat with an orange glaze? Too bad, the combination of vitamin C and fat will increase your risk of cancer. There are countless interactions between random nutrients, and no diet is going to be able to include all of the positives and none of the negatives.
In this sense, Soylent is your best option for maximizing the benefits of nutrient interactions because it’s so well controlled. As our knowledge improves, you can either micromanage your diet (peas and carrots but not corn, or corn and cauliflower but no beans, etc) or you can have a meal designed to mathematically optimize for the positives while decreasing the negatives. We don’t know what’s missing from Soylent, but then we also don’t know what’s missing from any other diet. The big difference is that Soylent uses the full extent of human knowledge to create a meal whose healthiness is only limited by the pace of cutting-edge research. You’re not going to get that from any other diet.
Finally, on burden of proof. Ugh, I’ve started to write this section out too many times and can’t find a good way to approach it. Just… don’t get too caught up on burden of proof. Russell’s teapot applies to claims we can’t scientifically provide evidence against (e.g. there is a teapot floating in space, there is a god), but we can (and have) provided evidence against the claim “we should be concerned that soylent is lacking important nutrients”. I think everyone’s time would be better spent looking up evidence one way or the other, rather than saying “You look it up”, because that evidence does exist for both sides.