Most multivitamins skip the same five nutrients: vitamin K2, iodine, choline, MSM, and amino acids. None of them are obscure. All of them have an evidence base. They get left out because they cost more, take too much space in a capsule, or both. Here’s what each one does and why the absence matters.
The short version
- Vitamin K2 (ideally MK-4) routes calcium into bone and away from arteries.
- Iodine (75-150ug) keeps thyroid hormone synthesis on the road. UK intake has drifted down.
- Choline (100-550mg) supports brain methylation and liver function. Around 90% of adults sit below the adequate intake.
- MSM (500-1500mg) supplies sulfur for joints, collagen, and connective tissue.
- Amino acids (glycine, taurine, EAAs) are the structural ingredients almost no pill-format multi has room for.
1. Vitamin K2 in the right form
Vitamin K2 activates two proteins that decide where calcium goes: osteocalcin (which puts it into bone) and matrix Gla protein (which keeps it out of arteries). Without enough K2, both proteins sit unactivated. Surveys of healthy adults find a meaningful share circulating with undercarboxylated osteocalcin even when vitamin K1 intake looks adequate (NIH Office of Dietary Supplements, Vitamin K).
Two K2 forms appear on labels: MK-4 and MK-7. MK-4 is the form found in animal tissue and the one used in the high-dose Japanese osteoporosis trials. MK-7 has a longer plasma half-life and a smaller body of low-dose efficacy evidence. Brands often choose MK-7 because it’s cheaper to formulate and easier to claim “long-acting.” MK-4 is closer to what your tissues actually deposit.
Most multivitamins contain vitamin K1 (phylloquinone). The body converts some K1 to K2, but inefficiently. Including K2 directly skips the conversion step. Worth checking your label for. (More on the D3 and K2 synergy here.)
2. Iodine, the mineral men’s multis often drop
The thyroid uses iodine to make T3 and T4. Without enough, hormone production slows and downstream metabolism slows with it. UK National Diet and Nutrition Survey data place women of reproductive age below the iodine LRNI on average, and overall population intake has been drifting downward as dairy and salt iodisation patterns shift (NHS, Iodine).
Iodine often disappears from men’s multivitamins for a specific reason: brands worry about supplementing it on top of an older man with an undiagnosed thyroid nodule, and play it safe by removing it. The result is a formula that swings too far the other way. A nutritional dose of 75-150ug from sea kelp or potassium iodide covers the average dietary gap without approaching pharmacological territory (NIH ODS, Iodine).
3. Choline, the methyl donor most men skip
Choline supports phospholipid membrane structure, methylation (via betaine), and acetylcholine production. Analyses of NHANES intake data put around 90% of US adults below the adequate intake of 550mg for men and 425mg for women (NIH ODS, Choline).
Most multivitamins skip choline entirely. The reason is bulk: choline ingredients are heavy and take up more capsule space than brands want to give them. A 100mg dose of phosphatidylcholine isn’t a complete replacement for the dietary gap, but it covers a meaningful share and contributes phospholipids the body can use directly.
If you eat two or more eggs a day, your intake is probably fine. Most men don’t. (We have a longer post on choline forms and brain function if you want the deeper read.)
4. MSM, the sulfur source for connective tissue
Methylsulfonylmethane (MSM) supplies elemental sulfur, which the body uses for collagen crosslinks, joint cartilage, and methylation pathways. Small trials in osteoarthritis report reduced pain scores at 1.5-6g daily, with the strongest evidence at the higher end (NCCIH overview, joint supplements). A 500mg dose sits below those clinical study ranges but supplies a daily sulfur input most diets undersupply.
Most multivitamins exclude MSM. The reason is, again, space. At doses that do anything, MSM crowds out other ingredients in a capsule or tablet format. Powder formats have room.
5. Amino acids, the structural ingredient nobody pills
Almost no pill-format multivitamin contains amino acids at any dose that does work. A single capsule holds around 500-700mg of total ingredient weight. The 9 essential amino acids alone need 5-10g for a daily input that matters.
Three amino acids in particular tend to be undersupplied:
- Glycine supports collagen synthesis, glutathione production, and sleep quality. Trials at 3g report improved subjective sleep markers (PubMed, glycine sleep research).
- Taurine supports cardiovascular function and bile acid synthesis. Dietary intake has fallen as red meat consumption has fallen.
- The 9 essential amino acids are required for muscle protein synthesis, with leucine the trigger above roughly 2.5g per serving.
A daily supplement in powder format has room to include amino acids at meaningful doses. A capsule simply does not.
What this means for your label
These five ingredients aren’t exotic. They’re well-studied, easy to source, and routinely left out because format constraints or formulation cost rule them out. Once you know what’s missing, the gaps tend to stand out. Look at your own label.
Fireblood is a daily powder. It contains all five: 120ug MK-4, 75ug iodine from sea kelp, 100mg phosphatidylcholine, 500mg OptiMSM, and 12 amino acids including 1000mg glycine and 500mg taurine. The full label is on our site if you want to check. We sell a powder in a tub. We know. But this powder includes the things most pills skip.
