Resveratrol and nicotinamide mononucleotide (NMN) are two supplements frequently discussed in longevity research, but choosing between them requires careful consideration of the evidence, safety, and regulatory status. Resveratrol, a polyphenolic compound found in red grapes and berries, has been studied for potential cardiovascular and metabolic benefits, though human trial results remain inconsistent. NMN, a precursor to NAD+, shows promise in preclinical studies but is classified as a novel food in the UK and is not currently authorised for sale without Food Standards Agency approval. Neither supplement has robust evidence demonstrating clear anti-ageing or longevity benefits in humans, and both lack extensive long-term safety data.

What Are Resveratrol and NMN?

Resveratrol is a naturally occurring polyphenolic compound found in red grapes, berries, peanuts, and Japanese knotweed. It belongs to a class of plant compounds called stilbenes and has been studied for its potential antioxidant and anti-inflammatory properties. Resveratrol gained public attention following observations about red wine consumption and heart health, though the concentrations in wine are relatively modest. The UK Chief Medical Officers advise not to drink alcohol for health benefits and to limit intake to no more than 14 units per week. As a dietary supplement, resveratrol is typically available in doses ranging from 100 to 500 mg daily, though there is no established recommended daily allowance in the UK.

Nicotinamide mononucleotide (NMN) is a precursor molecule in the biosynthesis of nicotinamide adenine dinucleotide (NAD+), a coenzyme essential for cellular energy metabolism and DNA repair. NAD+ levels naturally decline with age, and NMN supplementation has been proposed as a means to restore these levels. NMN is found in small quantities in foods such as broccoli, cabbage, cucumber, and edamame. Unlike resveratrol, which has been available as a supplement for decades, NMN is classified as a novel food in the UK and is not currently authorised for sale as a food supplement without Food Standards Agency (FSA) approval.

Both compounds have attracted considerable interest in longevity research, with proponents suggesting they may influence ageing processes at the cellular level. However, it is important to recognise that most evidence comes from preclinical studies in cell cultures and animal models, particularly mice. Human clinical trial data remain limited, and neither compound is currently licensed as a medicine by the MHRA for any specific therapeutic indication. If considering supplements, choose products from reputable UK suppliers with third-party testing or certificates of analysis, as quality can vary significantly between manufacturers.

Comparing the Evidence: Resveratrol vs NMN

Resveratrol has been investigated in numerous preclinical studies, where it has been suggested to influence sirtuins—a family of proteins involved in cellular regulation and longevity pathways—though the direct activation of SIRT1 by resveratrol remains debated in scientific literature. Animal studies have suggested potential benefits for cardiovascular health, glucose metabolism, and neuroprotection. However, human clinical trials have yielded mixed and often modest results. Systematic reviews of randomised controlled trials have found that resveratrol supplementation may have small beneficial effects on certain cardiovascular risk markers, such as systolic blood pressure (reductions of 2-6 mmHg) and modest improvements in fasting glucose, but the clinical significance of these changes remains uncertain. Importantly, resveratrol has poor bioavailability—it is rapidly metabolised in the liver and gut, meaning only a small fraction reaches systemic circulation in its active form.

NMN research is at an earlier stage. Preclinical studies in rodents have demonstrated that NMN supplementation can increase NAD+ levels in various tissues and may improve markers of metabolic health, insulin sensitivity, and mitochondrial function. Early-phase human trials have shown that NMN is generally well-tolerated and can increase blood NAD+ levels, but evidence for clinically meaningful health outcomes is still emerging. A small Japanese study published in 2022 (involving 42 participants taking 250mg NMN daily for 12 weeks) suggested improvements in muscle insulin sensitivity in prediabetic individuals, but larger, longer-term trials are needed to confirm these findings.

When comparing the two, resveratrol has a longer track record of human research, albeit with inconsistent results, whilst NMN is supported by promising preclinical data but lacks extensive human validation. Neither compound has robust evidence from large-scale, long-term randomised controlled trials demonstrating clear health benefits in humans. NICE does not currently provide guidance on either supplement, as they are not recognised treatments for any specific condition. Individuals considering these supplements should be aware that there is no official link between supplementation and proven anti-ageing or longevity benefits in humans at present.

Safety and Side Effects of Resveratrol and NMN

Resveratrol is generally considered safe when taken at typical supplemental doses (up to 500 mg daily) for short to moderate durations. Reported adverse effects are usually mild and may include:

• Gastrointestinal symptoms such as nausea, diarrhoea, or abdominal discomfort

• Headache

• Potential interactions with anticoagulant and antiplatelet medications

Higher doses (above 1 gram daily) have been associated with more frequent gastrointestinal side effects in clinical trials. There is limited long-term safety data beyond 12 months of continuous use. Resveratrol may interact with cytochrome P450 enzymes, potentially affecting the metabolism of certain medications. Individuals taking anticoagulants (including warfarin and direct oral anticoagulants like apixaban or rivaroxaban), antiplatelet agents (such as aspirin or clopidogrel), or those with bleeding disorders should exercise caution and consult their GP before starting resveratrol supplementation. Consider stopping resveratrol 1-2 weeks before planned surgery due to theoretical bleeding risks, and inform your surgical team about any supplements you take.

NMN appears to be well-tolerated in the limited human studies conducted to date, with doses up to 500 mg daily reported as safe over periods of several weeks to months. Adverse effects have been minimal, though some individuals report:

• Gastrointestinal upset

• Fatigue or sleep disturbances (anecdotal reports)

However, long-term safety data for NMN in humans is lacking, and its effects during pregnancy, breastfeeding, or in individuals with chronic health conditions have not been adequately studied. There is also ongoing scientific debate about whether chronically elevated NAD+ levels might have unintended consequences, as NAD+ plays complex roles in cellular processes including DNA repair and inflammation.

Important safety advice: Neither supplement should be considered a substitute for evidence-based medical treatment. Neither is recommended for children, adolescents, pregnant or breastfeeding women due to insufficient safety data. If you are taking prescribed medications, have existing health conditions, or experience any adverse effects after starting supplementation, consult your GP or a registered pharmacist promptly. Report any suspected adverse reactions to the MHRA Yellow Card Scheme (yellowcard.mhra.gov.uk).

Which Should You Choose: Resveratrol or NMN?

The decision between resveratrol and NMN—if one must be chosen—depends on individual circumstances, health goals, and tolerance for scientific uncertainty. Neither supplement has definitive evidence supporting superiority over the other for any specific health outcome in humans.

Consider resveratrol if you are interested in a compound with a longer history of human research, particularly if you have cardiovascular risk factors and are looking for a supplement with modest, though inconsistent, evidence for metabolic and cardiovascular markers. Resveratrol may be more suitable for individuals who prefer a well-established supplement profile, despite its bioavailability limitations. It is also generally more affordable and widely available in the UK market.

Regarding NMN, it's important to note that as a novel food, NMN is not currently authorised for sale as a food supplement in the UK without FSA approval. Products available online may not comply with UK regulations. If you are specifically interested in NAD+ precursors, consult with a healthcare professional about evidence-based alternatives or properly regulated products.

Key considerations for both:

• Evidence base: Neither has robust proof of anti-ageing or longevity benefits in humans

• Regulation: Check regulatory status; quality can vary between manufacturers

• Cost-effectiveness: The expense may not be justified given the current evidence

• Lifestyle factors: A balanced diet, regular physical activity, adequate sleep, and smoking cessation have far stronger evidence for promoting healthy ageing than any supplement

When to contact your GP: If you are considering these supplements and have existing health conditions, take regular medications, or experience any adverse effects after starting supplementation, seek medical advice. Your GP can provide personalised guidance based on your individual health profile and in line with NICE guidance on cardiovascular risk assessment (NG238) and hypertension management (NG136).

Ultimately, neither supplement should be viewed as essential for health or longevity. The most evidence-based approach to healthy ageing remains adherence to established lifestyle measures recommended by the NHS and appropriate management of cardiovascular and metabolic risk factors in line with NICE guidance.

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