Foods that contain nicotine include a variety of common vegetables, teas, and other plant-based products, many of which belong to the Solanaceae family, also known as nightshades. Notable among these are eggplants, tomatoes, and potatoes, which contain trace amounts of nicotine significantly lower than those found in tobacco products.[1][2] While nicotine is primarily associated with tobacco, its presence in certain foods highlights the diverse occurrence of this alkaloid in nature.[3] Understanding the nicotine content in foods can provide insight into dietary intake and potential health implications, albeit minimal compared to smoking.[4]

The Solanaceae family, which encompasses vegetables such as eggplants, tomatoes, and potatoes, is known for its nicotine content. Eggplants have the highest nicotine concentration among these vegetables, with approximately 100 micrograms per gram.[1] Tomatoes and potatoes, particularly in their unripe or green states, also contain nicotine, though in much smaller quantities.[2][5] These foods contribute minimally to overall nicotine intake due to their low concentration, posing no significant health risk.[6] Research has focused on how the nicotine content in these foods may affect dietary nicotine exposure and its implications for health, although it remains a subject of ongoing study.[7]

Apart from vegetables, certain teas are also known to contain trace amounts of nicotine, albeit in lower concentrations compared to nightshade vegetables.[8] The presence of nicotine in tea is a natural phenomenon, serving as a defense mechanism for the plant. The concentrations in tea and other foods are far lower than those in tobacco, underscoring the wide variety of plants that naturally produce nicotine.[9] This presence is generally considered safe for consumption and does not pose the same health risks associated with tobacco use.[10]

While the presence of nicotine in everyday foods is not widely known, it remains an interesting area of research and public discussion. Most people are unaware that the nicotine they consume from certain foods is negligible compared to what is absorbed through smoking.[11] This distinction is important in understanding dietary sources of nicotine and their implications. Despite the negligible levels, these foods are not associated with the health risks seen with tobacco products, offering reassurance about their safety in a typical diet.[12]

Several common vegetables contain trace amounts of nicotine, primarily those belonging to the Solanaceae family, also known as nightshades. Among these, eggplant is noted for having the highest concentration of nicotine. On average, eggplant contains approximately 100 micrograms of nicotine per gram, making it the richest in nicotine among commonly consumed vegetables[1][2]. Potatoes also contain nicotine, with an average of about 15 micrograms per gram. However, green and ripening potatoes exhibit higher levels, approximately 42 micrograms per gram[3][2].

Tomatoes are another source of nicotine, although their nicotine concentration varies with ripeness. Green tomatoes contain significantly more nicotine, approximately 42.8 micrograms per gram, compared to ripe tomatoes, which have about 7.1 micrograms per gram[1][4][5][2]. Additionally, pureed tomatoes have been reported to contain higher concentrations, at around 52 micrograms per gram[5].

Other vegetables, while not part of the nightshade family, also possess small amounts of nicotine. For instance, cauliflower contains about 16.8 micrograms of nicotine per gram[6][2]. Despite the presence of nicotine in these foods, the levels are minimal compared to those found in tobacco, and they are generally considered safe for consumption[7][8].

Apart from the well-known nightshade vegetables, several other foods contain trace amounts of nicotine. Among these, green peppers and cauliflower stand out. While cauliflower is not part of the nightshade family, it still contains approximately 16.8 'g of nicotine per gram[9][2]. Similarly, green tomatoes, although not as mature as their ripe counterparts, contain nicotine, albeit in smaller quantities[9][1].

These foods, although containing nicotine, are generally not associated with any harmful effects due to the relatively low concentrations present in them[7][10]. Furthermore, these nicotine-rich foods are often accompanied by beneficial nutrients such as iron, vitamins, and minerals, contributing positively to one's diet and immune system[10]. The presence of nicotine in these foods does not make them addictive, as the levels are significantly lower compared to tobacco products[10].

Tea, although not part of the nightshade family, has been found to contain trace amounts of nicotine[11]. The presence of nicotine in tea is a natural occurrence, as it functions as a defense mechanism in the plant[11]. While the nicotine levels in tea are significantly lower compared to those found in tobacco products, the presence of this alkaloid highlights the wide variety of plants where nicotine can naturally occur[12].

The analysis of nicotine content in foods, particularly within the Solanaceae family, has become an area of interest due to its potential impact on dietary nicotine intake. The most sensitive comprehensive laboratory analysis to date has focused on determining nicotine levels in edible Solanaceae, such as tomatoes, potatoes, aubergines, and peppers, as well as their processed products[13][4]. It was found that these foods contain measurable amounts of nicotine, albeit in small quantities[14].

To assess nicotine concentration, the median dry-weight nicotine content was utilized, accounting for variables such as water content, ripening, peeling, and cooking, which may influence nicotine levels[13]. Notably, nicotine in these foods is measured in micrograms per gram ('g/g), a significantly lower concentration than found in tobacco products[15]. For instance, tomatoes contain approximately 0.00001 mg of nicotine per gram, with unripe (green) tomatoes containing five times this amount[16].

In terms of dietary consumption, an average serving of eggplant contains about 0.06 mg of nicotine, while tomatoes have around 0.04 mg per serving. Other vegetables such as potatoes, cauliflower, and green peppers have even lower nicotine contents, roughly 0.02 mg per serving[17]. The presence of nicotine in these foods is considered low enough that it contributes only minimally to overall nicotine intake compared to smoking[18].

The presence of nicotine in certain foods raises questions about its health implications, particularly when consumed in typical dietary amounts. Nicotine is primarily associated with tobacco products, but it is also found in small quantities in several foods, including those from the Solanaceae family, such as tomatoes, potatoes, eggplants, and peppers[18][16]. The nicotine content in these foods is significantly lower than that in cigarettes, with, for example, green bell peppers containing 0.0000077 to 0.000009 mg of nicotine per gram compared to the 1-2 mg of nicotine found in a cigarette[16]. Despite these low levels, dietary intake can contribute to the nicotine metabolites detected in biological fluids, which can often be misinterpreted as exposure to environmental tobacco smoke[19].

In terms of health effects, nicotine has been noted to have both positive and negative impacts. Positively, nicotine can stimulate tissue growth and increase blood flow, aiding in the repair of damaged areas[20]. Additionally, some studies suggest potential benefits such as reduced incidence of certain conditions like canker sores and uterine fibroids[20]. However, the health risks associated with nicotine, particularly from smoking, such as addiction and cardiovascular issues, are well-documented.

It is important to differentiate between the effects of nicotine from smoking and that from dietary sources. While the nicotine content in foods is much lower, habitual consumption could still contribute to the overall nicotine load in the body, albeit minimally[16]. There is ongoing research to determine how dietary nicotine might affect health, and it is generally considered to be of minimal concern compared to nicotine intake from smoking or vaping[21]. Furthermore, for those looking to support gut health, incorporating probiotic-rich foods alongside nicotine-containing vegetables might be beneficial[21].

Several studies have investigated the presence of nicotine in foods and its implications for human health. Nicotine, primarily known for its prevalence in tobacco plants, has also been detected in various edible plants belonging to the Solanaceae family, which includes potatoes, tomatoes, and eggplants[14]. The presence of nicotine in these foods is notable because it suggests potential dietary sources of nicotine aside from tobacco consumption[19][14].

Epidemiological studies have explored the potential health impacts of consuming these Solanaceae plants. Some findings indicate an inverse relationship between the consumption of such foods and the incidence of certain health conditions, such as Parkinson's disease. For instance, diets high in vegetables, including tomatoes and peppers, have been associated with a lower risk of developing Parkinson's disease[13]. However, much of this research is still emerging, and this particular study on the dietary intake of nicotine from non-tobacco sources is among the first of its kind[13].

Further investigations into nicotine biosynthesis have also provided insights into how these plants produce nicotine. In tobacco (Nicotiana tabacum), nicotine and related pyridine alkaloids are synthesized in the roots and accumulate in the leaves through a jasmonate-mediated signaling cascade. Genetic studies have identified regulatory loci involved in this process, enabling the development of tobacco plants with low nicotine levels[22][23][24]. These insights contribute to understanding how nicotine might also be present in other plants within the Solanaceae family, though the exact biosynthetic pathways in these edible plants require further elucidation.

Environmental and agricultural factors play a significant role in influencing nicotine content in plants. Agronomic practices that enhance plant health and yield generally have a positive effect on nicotine production and accumulation. Key factors affecting nicotine concentrations include nitrogen fertilization, planting density, topping practices, sucker control, and harvesting techniques [25].

Differences in environmental conditions, such as those between glasshouse and field environments, can affect nicotine and other secondary metabolite levels. These variances may include factors like UV-B exposure, which can impact the nicotine content in both wild-type and genetically modified plants, though studies have shown no significant differences in nicotine levels between plants grown in these different conditions [26].

The manipulation of cultivation conditions is crucial for controlling nicotine levels. Adjustments in soil fertility and climate conditions, especially in greenhouse cultivation, can lead to desired nicotine concentrations in tobacco leaves, which are essential for cigarette production [27].

Planting density also significantly impacts nicotine content, particularly in the mid- and upper leaves of the plant. Higher plant populations tend to decrease nicotine concentrations in these areas, although the nicotine content of lower leaves remains largely unaffected [28].

Moreover, advancements in genetic methodologies, including mutational breeding and genetic engineering, have allowed for the development of tobacco plants with low or ultra-low nicotine levels. These technologies provide additional avenues for managing nicotine production in agricultural settings [29].

Understanding and leveraging these environmental and agricultural factors are critical for optimizing nicotine levels in plants, which can have implications beyond tobacco, extending to other Solanaceae family members and their dietary nicotine content [13].

Recent advances in molecular and genomics research have significantly contributed to the development of tobacco plants with low-nicotine or ultra-low nicotine traits. These traits are defined as having nicotine levels reduced to less than 20% or 5%, respectively, relative to standard levels[29]. This progress has been made possible through methodologies such as mutational breeding, genetic engineering, and genome editing, which allow precise modifications of the plant's genetic makeup[30][23].

The identification and manipulation of metabolic and regulatory genes involved in nicotine biosynthesis have been central to these advancements[23]. By targeting specific genes, such as the A622 genes involved in the latter steps of tobacco alkaloid biosynthesis, researchers have been able to influence nicotine content directly[31]. Whole tobacco plants with reduced activity of these genes are being explored to achieve the desired decrease in nicotine levels[31].

Moreover, genetic manipulation aimed at increasing nicotine content is also being evaluated for industrial purposes. Enhancing the efficiency of nicotine extraction from cultivated tobacco could have practical applications, particularly in the context of smoking cessation devices and alternative nicotine products[32]. These biotechnological approaches underline the dual potential of genetic advancements in both reducing and enhancing nicotine levels for various applications.

Public awareness regarding the presence of nicotine in everyday foods is relatively low. While it is common knowledge that tobacco products, including cigarettes and nicotine pouches, contain nicotine, fewer people are aware that certain foods also contain this alkaloid. Most foods with nicotine are derived from the Solanaceae family, commonly known as nightshades, which includes foods like tomatoes and potatoes[13][6]. Despite the presence of nicotine in these foods, the amount absorbed is negligible compared to active smoking and even lower than exposure from environmental tobacco smoke[13]. This lack of awareness might influence public perception, as the negligible levels of nicotine in these foods do not pose the same health risks associated with tobacco use. Understanding these distinctions can help in forming a more accurate perception of nicotine sources beyond traditional tobacco products.

The regulation of nicotine content in tobacco products is a significant aspect of public health policy. The 2009 Family Smoking Prevention and Tobacco Control Act granted the US Food and Drug Administration (FDA) the authority to set standards for nicotine levels and other constituents of tobacco products, aiming to protect public health[33][34]. This authority enables the FDA to mandate reductions in nicotine content, a measure intended to reduce the addictiveness of cigarettes and thus lessen the public health burden associated with smoking in the United States[35].

In the context of tobacco control, the FDA's regulatory framework emphasizes decreasing the addictiveness of cigarettes by potentially mandating a reduced nicotine product standard[36]. This regulatory approach considers the impact on various populations, including early young adults who smoke, and evaluates the implications of altering nicotine levels in cigarettes[36]. Such regulations are part of broader efforts to manage the public health implications of nicotine consumption and its associated risks.