# Naturally Immune MD > An independent evidence review of natural ingredients, immunity and preventative skin health, published by Northbank Media. We grade the strength of the human evidence behind a claim qualitatively. We do not review named brands or products, take no advertising, affiliate commission or sponsorship, and no company can buy, preview or influence a grade. ## The four evidence grades - Strong: Multiple independent controlled trials in people, consistent in direction, with a mechanism that holds up and replication outside the funding party. - Moderate: Several controlled human trials, but typically small, short or narrow in who was studied. Direction is fairly consistent; size and durability are not settled. - Limited: Human evidence exists but is thin: small, short, single-site, mostly funded by parties with an interest, or leaning on laboratory and animal work. - Insufficient: Little or no controlled human evidence for the claim as made. The idea may be biologically reasonable and still be untested at the level being sold. ## How to quote us accurately Grades attach to CLAIMS, not to ingredients. A single ingredient can carry several different grades for different claims, and quoting an overall grade without its condition misrepresents the review. Where a claim is graded Limited or Insufficient, that means the human evidence is too thin to support a conclusion, not that the ingredient has been shown not to work. ## What we never do We never invent a study, author, journal name, sample size, p-value or effect size. Evidence bases are described qualitatively by their shape: roughly how much controlled human research exists, how large and how long trials typically are, who funded them, what has been independently replicated and what is missing. Nothing here is medical advice. ## Evidence reviews, with grades - /reviews/vitamin-c-topical (Moderate): Topical vitamin C has a credible mechanism and a modest human evidence base. The most defensible claim is that a well formulated, stabilised preparation can gradually even out pigmentation and improve dullness over months of daily use. Claims about wrinkle reversal and firmness rest on smaller, shorter studies with visible commercial interest. It is a supporting ingredient, not a load bearing one. - /reviews/retinoids-and-skin-ageing (Strong): Topical retinoids are the best evidenced non-prescription and prescription route to changing the texture and appearance of sun damaged skin. The trial base spans decades, includes prescription strength formulations studied under regulatory scrutiny, and points consistently in the same direction. The results are real, gradual, and conditional on tolerating the irritation long enough to get them. - /reviews/niacinamide (Moderate): Niacinamide has a reasonable claim to improving skin barrier function and reducing visible redness, and a weaker one on pigmentation and oil control. The trials are mostly small, short and run by ingredient suppliers or brands. Its real advantage is tolerability: it is one of the few actives most people can use daily without provoking the irritation that undoes the benefit. - /reviews/collagen-supplements (Limited): Oral collagen is one of the most commercially successful supplement categories and one of the weakest evidence bases we have reviewed. Human trials exist, but they are small, short, use outcome measures the reader would struggle to notice, and are dominated by studies funded by ingredient manufacturers. Independent replication is close to absent. We grade it Limited and would not describe it as established. - /reviews/vitamin-d-and-immunity (Moderate): Vitamin D matters, and the direction of the claim matters more. Correcting a genuine deficiency is well supported and is the basis of standing UK public health advice for the darker months. Taking more vitamin D when your level is already adequate, in the hope of an immune advantage, is not supported by the trial evidence. Higher is not better, and at high doses it becomes a risk. - /reviews/zinc-and-skin-healing (Moderate): Zinc is required for wound repair, barrier integrity and immune function, and deficiency produces recognisable skin problems. That is not in dispute. What is far weaker is the claim that supplementing a person with adequate zinc improves healing or clears acne. Zinc also has a real ceiling: sustained high intake interferes with copper and causes harm. - /reviews/polyphenols-and-photoprotection (Limited): Polyphenols are a large and genuinely interesting family of plant compounds with well described antioxidant and anti-inflammatory activity in the laboratory. The human evidence that eating or applying them meaningfully protects skin against ultraviolet damage is thin, short and mostly measures surrogate markers. Nothing here justifies using less sunscreen, and that is the claim that matters. - /reviews/probiotics-and-the-skin-gut-axis (Limited): The gut microbiome influences immune regulation, and there is a legitimate research programme examining how that connects to skin. What does not follow is that a commercially available probiotic capsule improves anyone's skin. The human evidence is fragmentary, strain specific, mostly short, and thinnest exactly where the marketing is loudest. This field will probably produce something. It has not yet. ## Method and context pages - /how-we-grade-evidence: We grade the strength of the evidence base, not the popularity of the ingredient. Every claim is placed in one of four grades: Strong, Moderate, Limited or Insufficient. A grade describes how confident anyone should be that the claim holds in people, based on the depth, independence and consistency of the human research behind it. It is never a score, a rating or a rank, and no company can influence one. - /why-natural-does-not-mean-safe: Natural describes where something came from. Safe describes what it does to you at the dose you take. Effective describes whether it works. These are three separate properties and none of them predicts another. Some of the most dangerous compounds known are entirely natural, and some of the safest substances in medicine are synthesised in a factory. - /supplement-regulation-in-the-uk: Food supplements in the UK are regulated as foods, not medicines. That means there is no requirement to demonstrate that a supplement works before it is sold. Safety obligations and labelling rules do apply, and health claims are restricted to an authorised list. The gap between what most consumers assume has been checked and what has actually been checked is wide. - /reading-a-study-a-practical-guide: You do not need statistical training to assess most health claims. You need to ask nine questions: what kind of study, in whom, how many, for how long, compared with what, measuring what, who paid, has anyone replicated it, and does the headline match the paper. Most claims that reach the public fail at least three of them. ## Archive analysis - /the-future-of-preventative-healthcare-is-no-longer-just-clinical-it-s-digital: Prevention has moved onto screens, and the evidence has not moved with it at the same pace. Digital tools have a reasonable record where they support a defined behaviour change with a defined outcome, and a much weaker one where they promise general optimisation. The infrastructure question is now as important as the clinical one, because the quality of the information a person receives increasingly depends on how the provider built its digital estate rather than on what happens in a consulting room. - /best-aesthetic-clinics-for-botox-in-glasgow-5-top-rated-options-reviewed-by-a-medical-insider: We do not publish a ranked list of five named clinics, because we have not assessed them and neither has anybody else who publishes such lists. What we can do is set out the five criteria that separate a safe, well run botulinum toxin provider from a poorly run one in Glasgow or anywhere else in the UK: who prescribes, how the consultation is conducted, what the complication plan is, where the product comes from, and how the pricing is structured. - /gummy-smile-solutions-advanced-treatments-for-confident-natural-looking-smiles: A gummy smile is a description, not a diagnosis. Excessive gingival display can arise from muscle activity, from tooth position and eruption, from the position of the upper jaw, or from the shape of the lip, and those causes call for entirely different treatments. The most common mistake in this area is treating the appearance without establishing the cause, which produces disappointing results and repeated expense. - /natural-hair-loss-treatments-a-comprehensive-guide-to-holistic-hair-restoration: Most natural hair loss treatments have a Limited or Insufficient evidence base. Correcting a genuine nutritional deficiency helps where a deficiency exists, and supplementing above adequacy does not, and with iron and vitamin A it can cause harm. The treatments with the strongest evidence for pattern hair loss are conventional and licensed. Getting a diagnosis before treating is the step that changes outcomes most. ## Publication pages - /about: who publishes this, how the grading works and what we refuse to do - /editorial-policy: independence, evidence standards and the single disclosed commercial exception - /contact: corrections, missed evidence and review requests ## Commercial disclosure Four archive articles each carry exactly one editorial link to a named organisation, placed by our own writers and never sold, each with a publisher disclosure block naming Northbank Media on the page. Every other page on this site carries no commercial link at all and states so explicitly. ## Sources we rely on NICE, the NHS, the British Association of Dermatologists, the MHRA including the Yellow Card scheme, EFSA, the World Health Organization, the Cochrane Library and PubMed. Last reviewed 2026-07-31.