提到烟酰胺，许多人先想到的是精华液、提亮和皮肤屏障。它在护肤品中的知名度很高，以至于人们看到膳食补充剂里的烟酰胺时，也容易沿用同一套理解：既然外用研究与肤色、屏障有关，口服是不是也能直接“美白”？又或者，烟酰胺参与NAD⁺合成，补得越多就越能提高能量、延缓衰老？
这些联想都抓住了烟酰胺研究的一部分，却把不同使用路径、剂量层级和证据终点放在了一起。烟酰胺首先是一种维生素B3形式，也是人体合成烟酰胺腺嘌呤二核苷酸（NAD⁺）的重要原料之一。理解它，需要从营养身份出发，再分别看外用皮肤研究、口服营养研究与特定医学研究各自回答了什么。
一、先认清身份：烟酰胺是维生素B3的一种形式
维生素B3（旧称维生素PP、抗癞皮病因子）并不是单一分子，而是一组具有烟酸生物活性的化合物。营养学中最常见的两种形式是烟酸（nicotinic acid）和烟酰胺（又名尼克酰胺，nicotinamide，也常写作niacinamide）。维生素B3最终需要转化为重要的辅酶NAD⁺和NADP⁺，为各种生命活动提供支持。从化学结构看，烟酰胺是烟酸的酰胺形式，二者都能为人体合成NAD⁺和NADP⁺提供原料，因此都可作为维生素B3来源，但代谢路径、剂量反应和不良反应并不完全相同。此外，食物中的色氨酸也能经多步反应参与合成NAD⁺和NADP⁺，所以膳食营养评价使用“烟酸当量（NE）”合并计算维生素B3的来源。1 mg NE约等于1 mg烟酸，或60 mg膳食色氨酸。[1][2]
人体对维生素B3的基础需要并不大。《中国居民膳食营养素参考摄入量（2023版）》中，成年男性烟酸推荐摄入量为15 mg NE/天，成年女性为12 mg NE/天。[1] 日常饮食中，瘦肉、禽肉、鱼类、花生、全谷物都可以提供维生素B3。维生素B3长期摄入不足，或因酒精依赖、吸收障碍等原因无法正常利用时，严重缺乏可导致糙皮病。其经典表现被概括为“3D”：皮炎（dermatitis），常见于日晒暴露部位；腹泻（diarrhea）等消化道症状；以及认知、情绪和神经系统异常，严重时可出现痴呆（dementia），甚至危及生命。这主要是因为维生素B3最终转化的NAD⁺和NADP⁺在不同的生命活动中缺位而导致的。
这一营养身份是理解烟酰胺的起点。它能帮助身体满足NAD⁺合成的基础需求，但“参与合成”与“额外大量补充后持续提高某项指标”属于两个问题。前者已有成熟的营养学依据，后者还要看剂量、时间、组织分布和人体试验结果。
二、先理解基础生理作用，再认识NAD⁺
烟酸和烟酰胺进入体内后，可转化为NAD⁺/NADH和NADP⁺/NADPH等辅酶形式。它们参与大量氧化还原反应，是碳水化合物、脂肪和蛋白质释放能量的重要环节；NADPH还参与脂肪酸、胆固醇等物质的合成，并帮助维持细胞的抗氧化能力。[2][3] 因此，维生素B3最基础、也最成熟的作用，是支持正常能量代谢和细胞功能，而不是某一个孤立的“抗衰开关”。
在这些基础功能之外，NAD⁺还是多类酶的反应底物，涉及DNA损伤应答、细胞信号和代谢调节。这也是NAD⁺进入衰老研究的原因：随着年龄、炎症和代谢状态变化，某些组织的NAD⁺生成与消耗可能失去平衡，研究者因而尝试用不同前体进行干预。[3][4]
不过，“能参与NAD⁺合成”不等于补得越多越好，血液中的NAD⁺升高也不能自动等同于皮肤或其他器官功能改善。烟酸、烟酰胺、烟酰胺核糖（NR）和烟酰胺单核苷酸（NMN）虽然都与这条代谢网络有关，却是结构、代谢路径和研究剂量不同的原料。对烟酰胺的判断仍应回到具体形式、剂量、人群和研究终点；NR、NMN及NAD⁺干预的细节，则更适合另作专题讨论。[2][4]
三、皮肤研究重点之一：外用烟酰胺
烟酰胺在护肤领域的经典证据，关注的是局部皮肤环境。Hakozaki等2002年先在黑素细胞—角质形成细胞共培养模型中观察到，烟酰胺可使黑素小体转运减少35%～68%；同一论文还报告了两项日本女性人体试验：18名面部色素沉着受试者采用左右侧配对设计使用5%烟酰胺与基质，另有120名面部晒黑受试者接受含2%烟酰胺的防晒方案或相应对照，连续8周。与基质相比，使用4周后，烟酰胺组的面部色素沉着显著下降、肤色亮度显著提高。[5] Tanno等2000年在正常人角质形成细胞培养实验中发现，1～30 μmol/L烟酰胺连续处理6天，可使神经酰胺合成提高4.1～5.5倍，并提高葡糖基神经酰胺、鞘磷脂、游离脂肪酸和胆固醇的合成；在12名男性干性皮肤受试者的左右侧对照试验中，2%烟酰胺连续使用4周后，经皮水分流失较对照侧低27%，角质层游离脂肪酸和神经酰胺分别较对照侧增加67%和34%。[6] Bissett等2005年纳入50名有面部光老化表现的白人女性，采用随机、双盲、左右半脸对照设计，每日两次使用5%烟酰胺或基质、持续12周；与基质相比，细纹和皱纹、色素斑、泛红、肤色发黄及仪器测得的弹性均出现统计学显著改善。[7]
这些结果构成了外用烟酰胺用于提亮、屏障支持和改善光老化外观的主要证据链：成分直接作用于目标组织，浓度、载体和使用频率也围绕局部皮肤设计。口服后则要经历消化吸收、首过代谢、组织分配和排泄，暴露路径完全不同。因此，“减少黑素小体转运”不能未经验证就写成口服美白机制，外用百分比也不能换算成口服剂量。
同一个名字出现在护肤品和营养原料表中，不代表两条证据可以相互替代。先区分给药路径，再讨论功效，是理解烟酰胺时最重要的一道边界。
四、皮肤研究重点之二：口服烟酰胺
口服烟酰胺与皮肤的研究，需要按细胞和离体皮肤、动物、人体三个层级来看。不同层级可以相互提供线索，却不能彼此替代；尤其是“抗紫外线损伤”或“降低医学风险”，并不等于已经证明能够美白、淡纹或提升弹性。
Surjana等2013年采用HaCaT角质形成细胞和离体人皮肤模型，研究烟酰胺对模拟日光紫外线损伤后DNA修复的影响。他们观察到，烟酰胺可提高参与切除修复的细胞比例和单个细胞的修复速率，并减少环丁烷嘧啶二聚体（CPD）及8-氧代鸟嘌呤（8-oxoG）。[8] 这说明它可能支持受损细胞的修复过程，但仍属于机制与组织层面的证据。
在动物层级，Damian在2010年的综述中汇总的烟酰胺研究，主要观察紫外线后的免疫抑制等光损伤相关终点，并未报告皮肤黑色素或肤色变化。[9] 因而，这些动物结果不能用于证明口服烟酰胺具有美白、淡纹或提升弹性的作用。
人体研究需要按具体终点分别理解。Yiasemides等2009年开展两项随机、双盲、安慰剂交叉试验，分别纳入15名和16名健康志愿者；受试者口服烟酰胺1500 mg/天或500 mg/天，连续1周。与安慰剂阶段相比，两种剂量均显著减轻模拟日光造成的皮肤迟发型超敏反应抑制，且未影响未照射皮肤的免疫反应；两种剂量均耐受良好，未见有明显不良反应。[10] Chen等2015年的Ⅲ期随机、双盲、安慰剂对照试验纳入386名皮肤科高风险受试者，烟酰胺组使用500 mg、每日两次、持续12个月；试验期间，两组不良事件的数量和类型未见值得注意的差异。[11] 这些结果仅说明在相应试验人群、剂量和观察期内总体耐受性尚可，不能据此推导普通人的美容或日常防晒效果。
近年的结果也并非都指向一致。Faisal等2025年在47名健康志愿者中开展自身前后对照试验，受试者口服烟酰胺2000 mg/天、持续30天，UVB最小红斑量未显著改变（p=0.533），皮肤和尿液中的胸腺嘧啶二聚体也未显著减少。[12] Faisal等2026年的随机试验纳入50名健康志愿者，采用相同剂量和周期；烟酰胺组的UVA最小红斑量提高26%（p=0.0008），但皮肤和尿液中的胸腺嘧啶二聚体均未显著减少。[13] 这提示红斑反应、DNA损伤、免疫指标和长期皮肤结局不是同一件事，一味地大剂量使用烟酰胺并不是一个好策略。
总体看，口服烟酰胺已有光损伤和皮肤医学方向的人体研究，但直接以普通人肤色、皱纹、弹性为主要终点的高质量证据仍有限。现阶段更稳妥的说法是：口服烟酰胺首先是维生素B3营养来源，可能影响与紫外线应答和细胞修复有关的过程；尚不能据此外推为已经证实的口服美白或抗皱成分。防晒仍是预防光老化最直接的措施。
五、作为口服原料，维生素B3的剂量与安全性应该怎样看？
首先看原料身份。烟酰胺与烟酸都属于维生素B3来源，但不能只写成模糊的“NAD⁺前体”；产品还应明确具体形式、每份含量、纯度、杂质、稳定性和批次检测。NR、NMN是另外的原料，不应与烟酰胺的剂量和证据混用。
再看膳食参考值。《中国居民膳食营养素参考摄入量（2023版）》给出的成年男性烟酸RNI为15 mg NE/d，成年女性为12 mg NE/d；RNI用于评价大多数健康个体的日常需要。而安全上限UL建议提示维生素B3补充的边界：成人烟酸UL为15 mg/d，烟酰胺UL为310 mg/d。[1]
以每份添加50 mg烟酰胺为例，它约为成年男性RNI的3.3倍、成年女性RNI的4.2倍，能够覆盖基础营养需要；同时低于成人烟酰胺UL 310 mg/d。对一般健康成人而言，在同时计算饮食、复合维生素和其他补充剂来源后，50 mg处于有较大安全余量的范围。
还要区分两种形式的不良反应。较高剂量烟酸容易引起皮肤潮红、发热、刺痒等反应；烟酰胺通常不会产生同样的典型潮红。烟酰胺在数百毫克至克级研究剂量下虽总体耐受性较好，但随着剂量和使用时间增加，仍可能出现恶心、腹泻等胃肠道不适及肝酶变化；长期大量使用应接受专业评估。[14][15] 如补充后出现持续皮疹、瘙痒或其他异常反应，也应停用并咨询专业人员，而不应自行继续加量。
再次看配方位置。作为维生素B3来源，烟酰胺可与其他B族维生素共同支持能量代谢，但配方仍需避免简单堆高剂量。若目标是皮肤状态管理，还要考虑防晒、睡眠、蛋白质和微量营养素摄入、吸烟与血糖管理等更上游因素。单一原料很难覆盖皮肤色素、屏障、氧化压力和组织更新的全部路径。
最后看周期与适用人群。营养补充适合围绕饮食缺口和长期摄入结构来判断；数百毫克级及以上方案、慢性病人群、孕期与哺乳期人群，或正在使用药物的人群，应先咨询医生或营养专业人员。身体的稳定输出来自多条路径协同，这也是超级元料SUPER-SYN持续关注原料时更重视“放在什么系统里、承担哪一部分支持”的原因。
结语：从热门标签回到营养身份
烟酰胺同时出现在护肤、营养和NAD⁺研究中，说明它的生物学角色丰富，也更容易被跨场景外推。外用证据可以解释局部皮肤路径，口服证据首先支持维生素B3营养身份，特定高剂量研究则必须保留人群、剂量和终点限制。
真正值得关注的是，烟酰胺以什么形式进入身体、用了多少、持续多久，以及证据实际测量了什么；“美白”或“抗衰”的单一标签很难概括这些差别。把这些问题说清楚，烟酰胺才会从一个熟悉的热门成分，回到一类可以被准确理解、合理使用和长期评估的营养原料。
参考文献
- 中国营养学会. 中国居民膳食营养素参考摄入量（2023版）. 北京: 人民卫生出版社, 2023.
- Bogan KL, Brenner C. Nicotinic acid, nicotinamide, and nicotinamide riboside: A molecular evaluation of NAD⁺ precursor vitamins in human nutrition. Annual Review of Nutrition. 2008;28:115-130. DOI: 10.1146/annurev.nutr.28.061807.155443.
- Covarrubias AJ, Perrone R, Grozio A, Verdin E. NAD⁺ metabolism and its roles in cellular processes during ageing. Nature Reviews Molecular Cell Biology. 2021;22(2):119-141. DOI: 10.1038/s41580-020-00313-x.
- Migaud ME, Ziegler M, Baur JA. Regulation of and challenges in targeting NAD⁺ metabolism. Nature Reviews Molecular Cell Biology. 2024;25(10):822-840. DOI: 10.1038/s41580-024-00752-w.
- Hakozaki T, Minwalla L, Zhuang J, et al. The effect of niacinamide on reducing cutaneous pigmentation and suppression of melanosome transfer. British Journal of Dermatology. 2002;147(1):20-31. DOI: 10.1046/j.1365-2133.2002.04834.x.
- Tanno O, Ota Y, Kitamura N, Katsube T, Inoue S. Nicotinamide increases biosynthesis of ceramides as well as other stratum corneum lipids to improve the epidermal permeability barrier. British Journal of Dermatology. 2000;143(3):524-531. DOI: 10.1111/j.1365-2133.2000.03705.x.
- Bissett DL, Oblong JE, Berge CA. Niacinamide: A B vitamin that improves aging facial skin appearance. Dermatologic Surgery. 2005;31(7 Pt 2):860-865. DOI: 10.1111/j.1524-4725.2005.31732.
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- Damian DL. Photoprotective effects of nicotinamide. Photochemical & Photobiological Sciences. 2010;9(4):578-585. DOI: 10.1039/b9pp00146h.
- Yiasemides E, Sivapirabu G, Halliday GM, Park J, Damian DL. Oral nicotinamide protects against ultraviolet radiation-induced immunosuppression in humans. Carcinogenesis. 2009;30(1):101-105. DOI: 10.1093/carcin/bgn248.
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When people hear “nicotinamide,” many first think of serums, skin brightening, and barrier care. Its visibility in skincare is so high that the same assumptions are often carried over when nicotinamide appears in dietary supplements: if topical studies are related to skin tone and barrier function, can oral nicotinamide directly “whiten” or brighten the skin? And because nicotinamide participates in NAD⁺ synthesis, does taking more automatically mean more energy and slower aging?
These associations each capture part of the nicotinamide research landscape, yet they also combine different routes of use, dose levels, and study endpoints. Nicotinamide is first and foremost a form of vitamin B3 and one of the key raw materials the body can use to synthesize nicotinamide adenine dinucleotide (NAD⁺). Understanding it begins with its nutritional identity, followed by a separate look at what topical skin studies, oral nutrition studies, and specific medical studies have actually shown.
1. Start with Its Identity: Nicotinamide Is a Form of Vitamin B3
Vitamin B3 (historically known as vitamin PP or the anti-pellagra factor) refers to a group of compounds with niacin biological activity rather than a single molecule. The two most common forms in nutrition are nicotinic acid and nicotinamide (also called niacinamide). Vitamin B3 ultimately contributes to the formation of the essential coenzymes NAD⁺ and NADP⁺, which support a wide range of biological functions. Chemically, nicotinamide is the amide form of nicotinic acid. Both can provide substrates for the synthesis of NAD⁺ and NADP⁺ and therefore serve as vitamin B3 sources, although their metabolic pathways, dose responses, and adverse-effect profiles are not identical. Dietary tryptophan can also contribute to NAD⁺ and NADP⁺ synthesis through multiple metabolic steps. For this reason, nutritional assessment uses “niacin equivalents” (NE) to combine vitamin B3 sources. One milligram of NE is approximately equivalent to 1 mg of niacin or 60 mg of dietary tryptophan.[1][2]
The body’s basic requirement for vitamin B3 is relatively modest. In the Chinese Dietary Reference Intakes (2023 Edition), the recommended intake of niacin is 15 mg NE/day for adult men and 12 mg NE/day for adult women.[1] Lean meat, poultry, fish, peanuts, and whole grains can all provide vitamin B3 in a typical diet. Severe deficiency can occur when vitamin B3 intake remains inadequate for a prolonged period or when utilization is impaired by factors such as alcohol dependence or malabsorption. The resulting condition, pellagra, is classically summarized by the “3 Ds”: dermatitis, often affecting sun-exposed skin; diarrhea and other gastrointestinal symptoms; and cognitive, emotional, and neurological abnormalities that may progress to dementia and, in severe cases, become life-threatening. These manifestations arise in large part because NAD⁺ and NADP⁺, which depend on vitamin B3 metabolism, are required across many essential biological processes.
This nutritional identity is the starting point for understanding nicotinamide. It can help the body meet its basic requirements for NAD⁺ synthesis. Participating in that synthesis, however, is a different question from whether additional high-dose supplementation can continuously raise a specific biomarker or improve a particular outcome. The former is well established in nutrition science; the latter depends on dose, duration, tissue distribution, and results from human trials.
2. Understand the Basic Physiological Role Before Looking at NAD⁺
After nicotinic acid and nicotinamide enter the body, they can be converted into coenzyme forms such as NAD⁺/NADH and NADP⁺/NADPH. These molecules participate in numerous redox reactions and are central to releasing energy from carbohydrates, fats, and proteins. NADPH also contributes to the synthesis of fatty acids, cholesterol, and other molecules and helps maintain cellular antioxidant capacity.[2][3] The most fundamental and well-established role of vitamin B3 is therefore to support normal energy metabolism and cellular function, rather than serving as a single isolated “anti-aging switch.”
Beyond these basic functions, NAD⁺ also acts as a substrate for several classes of enzymes involved in DNA damage responses, cell signaling, and metabolic regulation. This is one reason NAD⁺ has become a major topic in aging research. As age, inflammation, and metabolic status change, the balance between NAD⁺ production and consumption may shift in certain tissues, prompting researchers to explore interventions with different NAD⁺ precursors.[3][4]
The ability to participate in NAD⁺ synthesis does not mean that more supplementation is always better, and an increase in circulating NAD⁺ cannot automatically be interpreted as improved function in the skin or other organs. Nicotinic acid, nicotinamide, nicotinamide riboside (NR), and nicotinamide mononucleotide (NMN) all relate to the same broad metabolic network, but they differ in structure, metabolic pathways, and doses used in research. Nicotinamide should therefore be evaluated according to its specific form, dose, target population, and study endpoints. NR, NMN, and other NAD⁺-targeted interventions are better addressed as separate topics.[2][4]
3. One Major Area of Skin Research: Topical Nicotinamide
The classic evidence for nicotinamide in skincare focuses on the local skin environment. In 2002, Hakozaki et al. first observed in a melanocyte–keratinocyte co-culture model that nicotinamide reduced melanosome transfer by 35%–68%. The same paper also reported two human studies in Japanese women: 18 participants with facial hyperpigmentation used 5% nicotinamide and vehicle in a paired left-right facial design, while another 120 participants with facial tanning received a sunscreen regimen containing 2% nicotinamide or the corresponding control for 8 weeks. Compared with vehicle, facial pigmentation was significantly reduced and skin lightness significantly increased after 4 weeks in the nicotinamide group.[5] In 2000, Tanno et al. found in cultured normal human keratinocytes that treatment with 1–30 μmol/L nicotinamide for 6 days increased ceramide synthesis by 4.1- to 5.5-fold and also increased the synthesis of glucosylceramide, sphingomyelin, free fatty acids, and cholesterol. In a left-right comparison study involving 12 men with dry skin, 4 weeks of 2% nicotinamide reduced transepidermal water loss by 27% versus the control side, while stratum corneum free fatty acids and ceramides increased by 67% and 34%, respectively.[6] In 2005, Bissett et al. enrolled 50 White women with signs of facial photoaging in a randomized, double-blind, split-face controlled study. Participants applied 5% nicotinamide or vehicle twice daily for 12 weeks. Compared with vehicle, statistically significant improvements were reported in fine lines and wrinkles, hyperpigmented spots, redness, sallowness, and instrument-measured elasticity.[7]
Together, these findings form much of the evidence base for topical nicotinamide in skin brightening, barrier support, and improvement in the visible signs of photoaging. In these studies, the ingredient acts directly on the target tissue, and the concentration, vehicle, and application frequency are designed around local skin exposure. Oral intake follows a very different exposure pathway involving digestion, absorption, first-pass metabolism, tissue distribution, and excretion. Findings such as “reduced melanosome transfer” therefore cannot be converted into an oral skin-brightening mechanism without direct evidence, and topical percentage concentrations cannot be translated into oral doses.
The same ingredient name can appear in both skincare products and nutrition formulas without making the two evidence pathways interchangeable. Distinguishing the route of administration before discussing outcomes is one of the most important boundaries when interpreting nicotinamide research.
4. Another Major Area of Skin Research: Oral Nicotinamide
Research on oral nicotinamide and skin should be read across three levels: cell and ex vivo skin models, animal studies, and human trials. These levels can inform one another, yet each answers a different question. Evidence related to “protection against UV-induced damage” or “reduction of a medical risk” does not by itself demonstrate skin brightening, wrinkle reduction, or improved elasticity.
In 2013, Surjana et al. used HaCaT keratinocytes and ex vivo human skin models to investigate the effect of nicotinamide on DNA repair after simulated solar ultraviolet exposure. They observed that nicotinamide increased both the proportion of cells participating in excision repair and the repair rate per cell, while reducing cyclobutane pyrimidine dimers (CPDs) and 8-oxoguanine (8-oxoG).[8] These findings suggest that nicotinamide may support cellular repair processes after damage, although the evidence remains mechanistic and tissue-level.
At the animal level, studies summarized in Damian’s 2010 review focused mainly on photodamage-related endpoints such as UV-induced immunosuppression and did not report changes in skin melanin or skin tone.[9] These animal findings therefore do not establish that oral nicotinamide brightens skin, reduces wrinkles, or improves elasticity.
Human studies also need to be interpreted according to their specific endpoints. In 2009, Yiasemides et al. conducted two randomized, double-blind, placebo-controlled crossover trials involving 15 and 16 healthy volunteers, respectively. Participants took oral nicotinamide at 1,500 mg/day or 500 mg/day for 1 week. Compared with the placebo period, both doses significantly reduced simulated-sunlight-induced suppression of cutaneous delayed-type hypersensitivity without altering immune responses in unirradiated skin. Both doses were well tolerated, with no notable adverse effects reported.[10] In 2015, Chen et al. conducted a phase III randomized, double-blind, placebo-controlled trial in 386 dermatologically high-risk participants. The nicotinamide group received 500 mg twice daily for 12 months. During the trial, there were no noteworthy differences between groups in the number or types of adverse events.[11] These results support acceptable tolerability within the specific study populations, doses, and observation periods. They do not establish cosmetic benefits or routine photoprotection for the general population.
More recent findings have also been mixed. In 2025, Faisal et al. conducted a before-and-after controlled study in 47 healthy volunteers who took 2,000 mg/day of oral nicotinamide for 30 days. The UVB minimal erythema dose did not change significantly (p=0.533), and thymidine dimers in skin and urine were not significantly reduced.[12] In a 2026 randomized trial by Faisal et al. involving 50 healthy volunteers at the same dose and duration, the UVA minimal erythema dose increased by 26% in the nicotinamide group (p=0.0008), while thymidine dimers in skin and urine again showed no significant reduction.[13] These findings underscore that erythema responses, DNA damage, immune markers, and long-term skin outcomes are distinct endpoints. Routine use of very high-dose nicotinamide cannot be justified simply by assuming that more will produce broader skin benefits.
Overall, oral nicotinamide has been studied in humans in relation to photodamage and dermatologic outcomes, but high-quality evidence directly using skin tone, wrinkles, or elasticity as primary endpoints in the general population remains limited. A more evidence-aligned interpretation is that oral nicotinamide first serves as a nutritional source of vitamin B3 and may influence processes related to UV responses and cellular repair. Current evidence does not establish it as a proven oral skin-whitening, skin-brightening, or anti-wrinkle ingredient. Sun protection remains the most direct measure for preventing photoaging.
5. As an Oral Ingredient, How Should Vitamin B3 Dose and Safety Be Evaluated?
First, identify the ingredient form. Nicotinamide and nicotinic acid are both sources of vitamin B3, but a product should provide more than the vague description “NAD⁺ precursor.” The exact form, amount per serving, purity, impurity profile, stability, and batch testing should also be clear. NR and NMN are different ingredients and their doses and evidence should not be mixed with those of nicotinamide.
Next, consider dietary reference values. According to the Chinese Dietary Reference Intakes (2023 Edition), the recommended nutrient intake (RNI) for niacin is 15 mg NE/day for adult men and 12 mg NE/day for adult women. The RNI is intended to meet the daily needs of most healthy individuals. Tolerable upper intake levels (ULs) also help define the safety boundaries of vitamin B3 supplementation: the adult UL is 15 mg/day for nicotinic acid and 310 mg/day for nicotinamide.[1]
For example, a serving containing 50 mg of nicotinamide provides approximately 3.3 times the RNI for adult men and 4.2 times the RNI for adult women, covering basic nutritional requirements while remaining below the adult nicotinamide UL of 310 mg/day. For generally healthy adults, 50 mg leaves a relatively wide safety margin when total intake from food, multivitamins, and other supplements is also taken into account.
The adverse-effect profiles of the two main vitamin B3 forms should also be distinguished. Higher doses of nicotinic acid can readily cause flushing, warmth, and tingling or itching, whereas nicotinamide generally does not produce the same characteristic flushing response. Nicotinamide has generally been well tolerated in studies using doses from several hundred milligrams to gram levels, but gastrointestinal symptoms such as nausea and diarrhea, as well as changes in liver enzymes, may still occur as dose and duration increase. Long-term use at high doses warrants professional assessment.[14][15] Persistent rash, itching, or other unusual reactions after supplementation should also prompt discontinuation and consultation with a qualified professional rather than further self-escalation of the dose.
The ingredient’s role within the overall formula also matters. As a source of vitamin B3, nicotinamide can work alongside other B vitamins to support normal energy metabolism, while formulation should still avoid simply stacking unnecessarily high doses. If the goal is skin-state management, upstream factors such as sun protection, sleep, protein and micronutrient intake, smoking, and blood glucose management should also be considered. A single ingredient is unlikely to cover every pathway involved in pigmentation, barrier function, oxidative stress, and tissue renewal.
Finally, consider duration and the intended population. Nutritional supplementation is best evaluated in the context of dietary gaps and long-term intake patterns. Regimens in the several-hundred-milligram range or higher, as well as use in people with chronic conditions, during pregnancy or breastfeeding, or alongside medications, should be discussed with a physician or qualified nutrition professional first. Stable physiological function depends on coordination across multiple pathways. This is also why SUPER-SYN places particular emphasis on where an ingredient fits within a broader biological system and which part of that system it is intended to support.
Conclusion: Returning from Popular Labels to Nutritional Identity
Nicotinamide appears in skincare, nutrition, and NAD⁺ research because it has a broad biological role—and that same breadth makes it easy to extrapolate evidence across contexts. Topical evidence helps explain local skin pathways, oral evidence first supports its nutritional identity as vitamin B3, and specific high-dose studies must always retain their population, dose, and endpoint limitations.
What matters most is the form in which nicotinamide enters the body, how much is used, how long it is used, and what the evidence actually measured. A single label such as “whitening” or “anti-aging” cannot capture these differences. Once those questions are made clear, nicotinamide can be understood less as a familiar trend ingredient and more as a nutritional ingredient that can be evaluated accurately, used appropriately, and assessed over the long term.
References
- Chinese Nutrition Society. Chinese Dietary Reference Intakes (2023 Edition). Beijing: People’s Medical Publishing House; 2023.
- Bogan KL, Brenner C. Nicotinic acid, nicotinamide, and nicotinamide riboside: A molecular evaluation of NAD⁺ precursor vitamins in human nutrition. Annual Review of Nutrition. 2008;28:115-130. DOI: 10.1146/annurev.nutr.28.061807.155443.
- Covarrubias AJ, Perrone R, Grozio A, Verdin E. NAD⁺ metabolism and its roles in cellular processes during ageing. Nature Reviews Molecular Cell Biology. 2021;22(2):119-141. DOI: 10.1038/s41580-020-00313-x.
- Migaud ME, Ziegler M, Baur JA. Regulation of and challenges in targeting NAD⁺ metabolism. Nature Reviews Molecular Cell Biology. 2024;25(10):822-840. DOI: 10.1038/s41580-024-00752-w.
- Hakozaki T, Minwalla L, Zhuang J, et al. The effect of niacinamide on reducing cutaneous pigmentation and suppression of melanosome transfer. British Journal of Dermatology. 2002;147(1):20-31. DOI: 10.1046/j.1365-2133.2002.04834.x.
- Tanno O, Ota Y, Kitamura N, Katsube T, Inoue S. Nicotinamide increases biosynthesis of ceramides as well as other stratum corneum lipids to improve the epidermal permeability barrier. British Journal of Dermatology. 2000;143(3):524-531. DOI: 10.1111/j.1365-2133.2000.03705.x.
- Bissett DL, Oblong JE, Berge CA. Niacinamide: A B vitamin that improves aging facial skin appearance. Dermatologic Surgery. 2005;31(7 Pt 2):860-865. DOI: 10.1111/j.1524-4725.2005.31732.
- Surjana D, Halliday GM, Damian DL. Nicotinamide enhances repair of ultraviolet radiation-induced DNA damage in human keratinocytes and ex vivo skin. Carcinogenesis. 2013;34(5):1144-1149. DOI: 10.1093/carcin/bgt017.
- Damian DL. Photoprotective effects of nicotinamide. Photochemical & Photobiological Sciences. 2010;9(4):578-585. DOI: 10.1039/b9pp00146h.
- Yiasemides E, Sivapirabu G, Halliday GM, Park J, Damian DL. Oral nicotinamide protects against ultraviolet radiation-induced immunosuppression in humans. Carcinogenesis. 2009;30(1):101-105. DOI: 10.1093/carcin/bgn248.
- Chen AC, Martin AJ, Choy B, et al. A phase 3 randomized trial of nicotinamide for skin-cancer chemoprevention. New England Journal of Medicine. 2015;373(17):1618-1626. DOI: 10.1056/NEJMoa1506197.
- Faisal A, Philipsen PA, Lerche CM, et al. Changes in ultraviolet B radiation-induced DNA damage and erythema after oral nicotinamide and polypodium leucotomos in healthy volunteers: an intraindividual controlled trial. Photochemical & Photobiological Sciences. 2025;24(11):1951-1958. DOI: 10.1007/s43630-025-00807-7.
- Faisal A, Lerche CM, Douki T, et al. Changes in ultraviolet A radiation-induced thymidine dimers and erythema after oral nicotinamide or polypodium leucotomos extract in healthy volunteers: a randomized intraindividual trial. Photochemical & Photobiological Sciences. 2026;25(5):845-852. DOI: 10.1007/s43630-026-00884-2.
- Knip M, Douek IF, Moore WP, et al. Safety of high-dose nicotinamide: A review. Diabetologia. 2000;43(11):1337-1345. DOI: 10.1007/s001250051536.
- Hwang ES, Song SB. Possible adverse effects of high-dose nicotinamide: Mechanisms and safety assessment. Biomolecules. 2020;10(5):687. DOI: 10.3390/biom10050687.