Harm-reduction protocol
Smoker Defense Stack
People who currently smoke and are not stopping right now.
Read this first. Nothing on this page offsets the exposure. Every item below reduces damage at the margins while the exposure continues — that is the whole claim, and it is a modest one. For scale: in the Nurses' Health Study cohort, roughly 64% of deaths among current smokers were attributable to smoking, and excess all-cause mortality risk fell to that of a never-smoker about 20 years after quitting — with most of the excess vascular mortality resolving considerably faster than that. No supplement protocol produces an effect in that range, and none of the trials below claim to.
- Kenfield et al., JAMA 2008 — ~64% of deaths in current smokers attributable to smoking; excess all-cause mortality reaches never-smoker level ~20 years after cessation, with vascular risk falling fastest.
- Protocol items, each graded5
- Supplements to actively avoid1
- Markers worth tracking4
Do not take these
These appear before the protocol on purpose. Getting this part wrong does more harm than getting the rest of the page right does good.
Do not take beta-carotene supplements
This is the single most important line on the page. Two large randomised trials tested beta-carotene in smokers and both found MORE lung cancer in the supplemented group, not less. CARET was stopped early for harm. This is not a theoretical interaction or a dose-dependent caution — it is a supplement that has been shown, twice, in tens of thousands of smokers, to increase the outcome it was given to prevent. Check your multivitamin: many still contain it, and "provitamin A" on a label means beta-carotene. Beta-carotene from whole food has not shown this effect; the harm is specific to supplemental doses.
- Omenn et al., N Engl J Med 1996 (CARET) — Beta carotene plus vitamin A in smokers and asbestos-exposed workers: trial stopped early — lung cancer and cardiovascular death were increased, not reduced.
- ATBC Study Group, N Engl J Med 1994 — Alpha-tocopherol and beta carotene in male smokers: higher lung cancer incidence in the beta-carotene arm.
What continuing actually costs
Sustained oxidative load, not an occasional hit
Cigarette smoke delivers a continuous oxidant burden that measurably depletes circulating ascorbate and shifts the ascorbate/dehydroascorbate ratio toward the oxidised form. This is why a smoker's antioxidant requirement is genuinely higher than a non-smoker's — it is a depletion problem, not a marketing claim.
- Lykkesfeldt et al., Am J Clin Nutr 1997 — Ascorbic acid and dehydroascorbic acid used as biomarkers of smoking-caused oxidative stress.
Most of the damage is not reversible by supplementation
Nothing on this page changes the carcinogen exposure itself. Tar-phase and gas-phase constituents form DNA adducts directly; an antioxidant taken hours later does not undo an adduct already formed. Treat this stack as reducing collateral oxidative and inflammatory cost, not as protection from the primary mechanism.
The protocol
Ordered by strength of evidence, not by cost or convenience. Each tier note says what the grade rests on, so you can judge it rather than take it on trust.
N-acetylcysteine (NAC)
Tier A· Clinical- Dose
- 600 mg twice daily
- Timing
- Morning and evening, with or without food
Glutathione precursor and mucolytic. This is the dose and schedule that reduced COPD exacerbations in a 1,006-patient randomised trial — the strongest human airway evidence in this stack, and the reason NAC leads it.
Why this grade: Tier A for exacerbation reduction in established moderate-to-severe COPD. That is not the same as "protects healthy smokers", and the trial did not test that.
- Zheng et al., Lancet Respir Med 2014 (PANTHEON) — NAC 600 mg twice daily for one year: 1.16 vs 1.49 exacerbations per patient-year, risk ratio 0.78 (95% CI 0.67–0.90), p=0.0011, n=1,006.
Sulforaphane (broccoli sprout extract)
Tier B· Emerging- Dose
- Standardised to 10–20 mg sulforaphane, or the glucoraphanin equivalent with active myrosinase
- Timing
- Morning, with food
The most direct NRF2 activator in the library. NRF2 drives the phase-II detoxification and antioxidant response that handles exactly the class of electrophiles tobacco smoke delivers.
Why this grade: Tier B. The NRF2 mechanism is well characterised and human airway work exists, but there is no large outcome trial in smokers. Graded on mechanism plus early human data, not on a hard endpoint.
Vitamin C
Tier B· Emerging- Dose
- 500 mg/day, split if tolerance is an issue
- Timing
- With meals
Replaces a documented, measurable depletion rather than topping up an adequate pool. Smokers sit lower on plasma ascorbate at equivalent intake.
Why this grade: Tier B for correcting the depletion itself. No mortality or cancer-endpoint benefit has been shown from supplementing it, and this page does not imply one.
- Lykkesfeldt et al., Am J Clin Nutr 1997 — Smoking-driven shift in the ascorbate/dehydroascorbate ratio.
GlyNAC (glycine + NAC)
Tier B· Emerging- Dose
- Glycine ~100 mg/kg/day with NAC ~100 mg/kg/day, if running it in place of NAC alone
- Timing
- Split across the day
Glutathione synthesis needs both cysteine and glycine. If you are already running NAC and want the fuller glutathione-restoration protocol rather than the airway-specific one, this is the version with the ageing-population trial data behind it.
Why this grade: Tier B here specifically. The GlyNAC trials were run in older adults for glutathione and mitochondrial markers — not in smokers, and not for respiratory endpoints.
Aged garlic extract
Tier C· Preclinical- Dose
- 1,200 mg/day
- Timing
- With food
Cardiovascular-directed rather than airway-directed. Smoking risk is not only pulmonary, and the vascular side of the exposure is where cessation benefit appears fastest — which makes it the side most worth supporting.
Why this grade: Tier C in this context. Reasonable vascular rationale, no trial in smokers specifically.
Interactions and cautions
High-dose vitamin E is not a free addition either
The same trial that found beta-carotene harm also tested alpha-tocopherol, and it did not deliver the hoped-for lung cancer reduction. Vitamin E at ordinary dietary-supplement levels is not the concern; treating high-dose isolated alpha-tocopherol as protective against smoking damage is not supported. Mixed tocopherols at food-equivalent doses are the more defensible choice.
- ATBC Study Group, N Engl J Med 1994 — No lung cancer benefit from alpha-tocopherol supplementation in male smokers.
NAC and nitrate-based heart medication
NAC can potentiate the vasodilatory effect of nitrates. If you take nitroglycerin or any long-acting nitrate, clear NAC with the prescriber before starting rather than after.
What to actually track
| Marker | Why it matters | Cadence |
|---|---|---|
| hs-CRP | Tracks the inflammatory component that responds first | Baseline, then 12 weeks |
| Spirometry (FEV1/FVC) | The endpoint that actually matters for airway decline | Annually |
| Blood pressure | Vascular risk is the fastest-moving part of smoking exposure, in both directions | Monthly at home |
| Full blood count | Smoking raises haematocrit and white cell count; a rising trend is worth knowing | Annually |
This page is educational and is not medical advice. It does not diagnose or treat anything, and it is not a substitute for a clinician who knows your history — which matters more here than on most pages, because several items above interact with prescription medicines. If you want help stopping rather than mitigating, that is a better outcome than anything on this page can deliver, and it is worth asking for. How TNiC grades evidence →