THREE BLOOD MARKERS WORTH KNOWING BEFORE YOU BUY ANOTHER SUPPLEMENT

The medicus who served with Legio II Traiana Fortis in Egypt in 120 AD examined the soldier before he prescribed anything. He did not issue the same compounds to every man regardless of that man's specific deficit. That single procedural detail is the difference between a supplement stack that works and a cabinet full of expensive guesses.

The Medicus Carried a Short List

The Legion's field pharmacopeia was small and specific. Willow bark — salicin, the compound that eventually became aspirin — for inflammation and pain. Vinegar for wound cleaning and gastrointestinal support on the march, the same posca the soldiers drank. Honey for wound dressing, its antibacterial properties documented in Egyptian papyri two thousand years before Fleming named penicillin. Thyme and garlic, both antimicrobial, both standard issue. Pine resin as a sealant for wounds that could not be closed.

The medicus did not carry these things because he believed in natural remedies. He carried them because they worked. The Legion applied one standard to everything — training methods, rations, recovery practices, pharmacology — and it was the same standard the quartermaster applied to grain and the engineer applied to road surfaces: does it make the soldier able to perform tomorrow? If yes, it stays. If no, it goes.

The modern supplement industry runs to thousands of products built on weak evidence and strong marketing. The list that survives that Roman standard is much shorter than the industry wants you to believe, and much more specific than most men ever get told.

The Three Tests — Run These Before You Buy Anything

Three blood markers determine which part of a supplement protocol you actually need and which part is redundant. The man who takes vitamin D3 while already sufficient is not harming himself. He is also not helping himself, and the Roman quartermaster did not issue supplies the unit already had.

1. Serum 25-hydroxy vitamin D. Most clinical standards define deficiency as below 20 ng/mL and insufficiency as 20–29 ng/mL. Most men over 40 who work indoors fall in the insufficient-to-deficient range regardless of latitude, and particularly from October through April. If you are above 40 ng/mL and eating oily fish consistently, skip the supplement. If you are below 30, that is a number to take to your physician rather than a gap to fill on your own guesswork.

2. Omega-3 index. This measures the percentage of EPA and DHA in red blood cell membranes — long-term omega-3 status, not a snapshot of last week's food. An index above 8 percent is associated with the lowest cardiovascular risk. Most Western adults without regular oily fish consumption test in the 4–6 percent range, and below 4 percent is associated with elevated inflammatory markers and impaired recovery. Above 8 percent with three fish meals a week, the fish oil is redundant. Below 6 percent, it is corrective.

3. RBC magnesium — not serum magnesium. Standard serum magnesium is nearly useless for assessing cellular status, because the body tightly regulates serum levels by pulling magnesium out of tissue. Red blood cell magnesium reflects intracellular status, which is what actually matters for sleep quality, muscle function, and cortisol regulation. Normal range runs 4.2–6.8 mg/dL. Most men reporting poor sleep and chronic stress test in the low-normal band. The book's protocol treats below 5.5 mg/dL as the point where magnesium becomes worth discussing; where your own number sits, and what to do about it, is a conversation for your physician.

The Legion medicus examined the soldier before prescribing. He did not issue the same compounds to every man regardless of his specific deficit.

The Foundation Tier — Daily, and Only Because the Evidence Earned It

The doses below are the ones the book's protocol uses and the ones the cited trials tested. They are reported here, not recommended to you personally — several of these compounds interact with prescription medication, and which of them belong in your own stack is a question for your physician.

Creatine monohydrate, 5 g daily, any time, with food. Dietary meat and endogenous synthesis together deliver roughly one to two grams per day — less than half the threshold research identifies for meaningful effect. Devries and Phillips pooled 22 randomized controlled trials covering 721 older adults who took creatine during resistance training versus training alone. The result was unambiguous: 1.37 kilograms more lean tissue mass and significantly greater strength gains in both upper and lower body. The effect was additive. It amplified the training stimulus rather than replacing it — meaning a man who is not training does not benefit meaningfully, and a man running a real strength week does. Monohydrate is the form with the strongest evidence base; no other form has beaten it in controlled trials despite higher price points. Roughly four weeks to fully saturate muscle phosphocreatine at this dose.

Fish oil, 2 g combined EPA plus DHA daily — only if three weekly servings of oily fish are not happening. The anti-inflammatory resolution pathway that terminates the acute inflammatory cascade after hard training requires EPA and DHA specifically, and the body cannot synthesize adequate amounts from plant-based omega-3 sources alone. Without them, inflammation that should resolve inside 48 to 72 hours extends, and the next session starts from incomplete recovery. If the three fish meals are consistent, skip the capsule — the food source is preferable where it is achievable. Take with the largest fat-containing meal of the day.

Vitamin D3, 2,000–4,000 IU with a fat-containing meal — if the test says you are deficient. Vitamin D is less a supplement than a hormone precursor the skin makes from sunlight, and indoor work removes the supply. A 2024 meta-analysis of seventeen randomized controlled trials found that supplementation significantly raised total testosterone in deficient men. That matters here because hypertrophy, strength gain, and cardiovascular adaptation are all testosterone-dependent processes — training six days a week with testosterone suppressed by a correctable deficiency runs the adaptation machinery at reduced capacity. Dietary vitamin D is insufficient at any realistic intake to correct deficiency.

Magnesium glycinate, 400 mg, thirty minutes before sleep. Abbasi and colleagues ran a double-blind placebo-controlled trial of magnesium in elderly subjects with primary insomnia and found significant improvements in sleep onset, sleep efficiency, total sleep time, and early morning waking, alongside reductions in serum cortisol and renin. The mechanism is NMDA receptor modulation — magnesium acts as a natural blocker, reducing the neurological arousal that keeps a man awake when cortisol is chronically elevated from combined training and life load. Glycinate is the preferred form: most bioavailable, least likely to produce the laxative effect that oxide or citrate can cause at higher doses.

The Recovery Tier Is Conditional, Not Daily

This is where most men get it wrong. Curcumin and tart cherry are responses to a training stimulus, not baseline supplements.

Curcumin, 500–1,000 mg of a bioenhanced preparation, in the 48 hours after the heaviest sessions of the week. Hillman and colleagues ran a double-blind crossover trial in which curcumin produced moderate-to-large reductions in pain during single-leg squat at 24 and 48 hours post-exercise compared to placebo. The mechanism is NF-κB inhibition — reduced transcription of the pro-inflammatory cytokines that drive delayed-onset soreness and tissue degradation. The bioavailability problem is real: standard curcumin powder absorbs poorly, and the trials showing effect used bioenhanced forms — curcumin with piperine, phytosome-based, or water-soluble extracts. Take with fat. Not daily unless joint symptoms warrant it.

Tart cherry concentrate, 30 ml in water before bed on high-load days. Tart cherries are one of the few food sources with measurable melatonin content, and their anthocyanins independently reduce inflammatory markers associated with exercise-induced muscle damage. Worth reading alongside our own harder look at the pooled trial data — what 19 tart cherry trials found, and what they didn't — which lands on faster return of force rather than less soreness, and a sleep benefit that shows up mainly in people who already sleep badly. Use the concentrate rather than a low-dose capsule.

The Adaptogen Tier — Only If Life Load Demands It

Ashwagandha, 300 mg of standardized root extract (KSM-66 or Sensoril) twice daily with food. Chandrasekhar and colleagues ran a prospective double-blind placebo-controlled study of a high-concentration ashwagandha root extract and found significant reductions in serum cortisol alongside improvements on validated stress and anxiety scales in chronically stressed adults. The relevance is specific: elevated cortisol from combined training and life stress suppresses testosterone, disrupts sleep architecture, and increases muscle catabolism. Ashwagandha does not remove the stress. It modulates the HPA-axis response to it, reducing the downstream hormonal cost. Four to eight weeks to full expression. Not a sedative, not a stimulant — a system regulator.

The Avoidance List Is Half the Protocol

The quartermaster's logic runs in both directions. Zhong and colleagues followed 91,891 American adults for an average of 13.5 years and found that participants in the highest quintile of ultra-processed food consumption had 50 percent higher cardiovascular mortality than those in the lowest quintile, with a consistent and linear dose-response relationship. That is not a marginal signal.

What leaves the protocol: refined seed oils, added sugar above trace amounts, processed grain products with no intact fiber structure, and packaged foods whose ingredient lists require a chemistry degree. These are not banned for moral reasons. They are removed because each has a specific mechanism by which it undermines the adaptation you are paying for.

The seed oil case is the clearest. Corn, soybean, sunflower, cottonseed, and canola oils deliver high concentrations of linoleic acid, an omega-6 fatty acid that competes with EPA and DHA for incorporation into cell membranes. A man taking two grams of fish oil daily and cooking with soybean oil is partially cancelling his own supplementation with his cooking fat. That is not ideology. It is membrane chemistry. Replace with extra-virgin olive oil, butter, or coconut oil.

Alcohol belongs here too, for a reason separate from sleep. Studies measuring muscle protein synthesis in the 24 hours after resistance training combined with alcohol have found suppression in the range of 24 to 37 percent versus training without it. The session happens, the mechanical signal goes out, and the repair response is partially suppressed by the presence of alcohol during the synthesis window. Train heavy Saturday and drink Saturday night and you are collecting roughly two-thirds of the adaptation you earned. Not a moral argument — a logistics argument.

The Protocol

• Run the three tests first. Vitamin D (25-OH), omega-3 index, RBC magnesium. The numbers tell you which Foundation items you need and which you can skip.
• Confirm the foundation is already running — training, nutrition, and sleep — before adding anything. The Legion did not hand a soldier a packet of supplements instead of a pound of grain.
• Start with the Foundation Tier only. Creatine daily. Fish oil if the fish isn't happening. D3 if the test says deficient. Magnesium glycinate before bed.
• Add the Recovery Tier as a training-load response, not a daily habit — curcumin and tart cherry in the window after your heaviest sessions.
• Add the Adaptogen Tier only if external stress load is genuinely high. The man who buys ashwagandha before stabilizing sleep and protein intake has spent money on the wrong problem.
• Track compliance daily, yes or no. These compounds work through consistency, and consistency requires a record. Thirty days of tracking tells you which supplements you are actually taking versus intending to take.
• Evaluate at ninety days, not thirty. Phosphocreatine saturates over four weeks. Vitamin D rises over six to twelve. Magnesium's sleep effect shows in two to four. Omega-3 membrane incorporation is a three-month process. A man evaluating at thirty days is evaluating incomplete processes. Retest vitamin D and the omega-3 index at ninety and check whether the numbers moved toward optimal.

The Bottom Line

None of this is pharmaceutical. It does not produce dramatic changes in short windows. It produces measurable changes in specific biomarkers and performance metrics across a timeline longer than most men's patience. The Legion medicus did not overmedicate — he gave the soldier what the situation required and removed it when the situation changed. Seven items, three tiers, three blood tests, and a ninety-day review. That is the whole protocol.

Blood testing and supplementation decisions belong with your physician, particularly if you take prescription medication — several compounds discussed here have documented interactions.