Which Part of Tomato is Not Good for Health? A Full Breakdown

December 31, 2025 •

4 min read

Historically, tomatoes were feared as poisonous fruits, a reputation stemming from their relation to nightshades. Today, while the ripe, red fruit is celebrated for its nutritional benefits, understanding which part of tomato is not good for health is crucial for safe consumption, especially concerning leaves, stems, and green tomatoes.

Quick Summary

The stems, leaves, and unripe green tomatoes contain toxic alkaloids and should not be eaten. Some individuals with sensitivities may also experience issues with the skin and seeds of ripe tomatoes due to fiber and lectins.

Key Points

Avoid Leaves and Stems: The highest concentration of toxic alkaloids is found in the leaves and stems of the tomato plant, and these should not be consumed.
Be Cautious with Unripe Fruit: Unripe, green tomatoes contain significant levels of tomatine, which decreases as the fruit ripens. It's best to avoid raw green tomatoes.
Consider Digestion Issues: Tomato skins and seeds are tough to digest due to high fiber and lectin content, which can cause discomfort, especially for individuals with sensitive guts or IBS.
Monitor for Acid Reflux: The acidity of tomatoes can trigger or worsen heartburn symptoms for those with GERD or acid reflux disease.
Address Kidney Health: Individuals prone to kidney stones should be mindful of the oxalates in tomato seeds, while those with kidney disease should watch the potassium content.
Cook Tomatoes for Safety: Thoroughly cooking tomatoes, especially green ones, can help break down alkaloids and improve digestibility.
Consult a Doctor for Sensitivities: If you experience adverse effects after eating tomatoes, consult a healthcare provider to rule out allergies or intolerances.

The Nightshade Family and Natural Defenses

Tomatoes belong to the nightshade family, or Solanaceae, which also includes potatoes, eggplants, and peppers. This family is known for producing compounds called alkaloids as a natural defense mechanism against pests and diseases. In tomatoes, the primary alkaloid is alpha-tomatine, which is present in higher concentrations in the green, unripe fruit and the vegetative parts of the plant, such as the leaves and stems. While the toxicity of tomatine is lower than that of solanine (the alkaloid found in potatoes), consuming large amounts can still cause gastrointestinal distress.

The Toxic Parts: Leaves, Stems, and Unripe Fruit

Contrary to popular belief that the entire tomato plant is deadly, the danger is concentrated in specific areas. The leaves and stems of the tomato plant contain the highest levels of tomatine and other alkaloids. While some culinary enthusiasts claim to use small amounts of leaves for flavoring, and some studies suggest the risk is low, most food safety advice warns against consuming them. It is best practice to discard these parts to avoid any potential risk. Similarly, unripe, green tomatoes, particularly those not specifically bred to be green when ripe, contain significant levels of glycoalkaloids. As the tomato ripens and turns red, the tomatine levels significantly decrease, making the ripe fruit safe to eat. Cooked green tomatoes, like those in fried green tomato dishes, are generally considered safe as the cooking process helps break down these compounds, though caution is still advised with large quantities.

Potential Issues with Ripe Tomatoes for Sensitive Individuals

For most people, eating ripe tomatoes is perfectly safe and healthy. However, certain characteristics of the ripe fruit can cause discomfort for specific individuals.

The Digestibility of Skin and Seeds

The skin of the tomato is composed largely of dietary fiber, including cellulose, which the human body cannot fully digest. While this fiber is beneficial for many, for those with sensitive digestive systems, like individuals with Irritable Bowel Syndrome (IBS), it can cause irritation, gas, and bloating. Similarly, tomato seeds are tough and indigestible. While they typically pass through the digestive system harmlessly, for people with diverticulitis, there's a risk of seeds getting lodged in the pouches of the colon, potentially causing inflammation. For these reasons, peeling and deseeding tomatoes, especially for sauces and purées, is a common practice.

The Acidity and its Effects

Tomatoes are naturally acidic, containing both citric and malic acids. This high acidity can be a trigger for individuals suffering from acid reflux or Gastroesophageal Reflux Disease (GERD), causing symptoms like heartburn. For those with sensitive stomachs, the acidic content can lead to general stomach upset.

The Oxalate and Potassium Content

Tomato seeds are high in oxalates, which can contribute to the formation of kidney stones in susceptible individuals. For people with a history of kidney stones, moderating tomato intake may be recommended. Furthermore, ripe tomatoes are rich in potassium. While potassium is a vital nutrient, it can be problematic for individuals with kidney disease, who need to carefully manage their potassium levels.

Comparison Table: Safe vs. Problematic Tomato Parts


Part of Tomato	Glycoalkaloid (Toxicity)	Digestibility	Potential Issues
Leaves & Stems	High concentration of tomatine. Avoid.	Indigestible	Gastrointestinal upset, toxic effects if consumed in large quantities
Unripe Green Fruit	Significant levels of tomatine. Caution.	Varies; some cooked green tomatoes are consumed.	Toxic effects if eaten raw in quantity; cooking helps but doesn't eliminate risk completely
Ripe Fruit (Flesh)	Very low levels. Generally safe.	Highly digestible	Acidity can trigger GERD/reflux in some
Ripe Fruit (Skin)	Very low levels. Generally safe.	Tough, fibrous, not fully digestible	Can cause bloating/gas, especially for those with IBS or sensitivities
Ripe Fruit (Seeds)	Very low levels. Generally safe.	Indigestible	High in oxalates (kidney stone risk); potential diverticulitis irritation

How to Enjoy Tomatoes Safely

For most individuals, the health benefits of ripe tomatoes, including their rich antioxidant (lycopene) and vitamin content, far outweigh any minor risks. However, adopting certain practices can help minimize any potential discomfort. Cooking tomatoes thoroughly, especially if using a recipe that calls for green ones, can significantly reduce alkaloid levels. If you have a sensitive stomach or a history of digestive issues, consider peeling and deseeding your tomatoes. Pairing tomatoes with less acidic foods, such as green leafy vegetables or potatoes, can also help neutralize their acidity. As with any dietary concern, consulting a healthcare provider or a registered dietitian is the best course of action if you suspect a sensitivity.

Conclusion: Navigating Tomato Consumption

In conclusion, while the ripe, red tomato is a healthy dietary staple, certain parts are best avoided for consumption due to toxic compounds or potential digestive issues. The leaves, stems, and unripened fruit contain potentially harmful levels of alkaloids and should be discarded. For people with specific sensitivities, the skin and seeds of ripe tomatoes can be challenging to digest and may aggravate conditions like IBS or GERD, while the high oxalate and potassium content can be a concern for those with kidney issues. By understanding these potential risks and adjusting preparation methods, you can safely continue to enjoy the flavor and nutritional benefits of this versatile fruit. For more detailed information on food safety, you can refer to authoritative sources like the Singapore Food Agency.

The Risks of Ignoring Tomato Safety

Consuming the harmful parts of a tomato plant, particularly the green leaves, stems, and unripe fruit, can lead to unpleasant or even dangerous side effects. Symptoms of glycoalkaloid poisoning often include nausea, cramps, diarrhea, and stomach pain. While typically mild, they can be more severe in large doses or for sensitive individuals. For those with pre-existing conditions like GERD or IBS, ignoring the potential effects of acidity, skins, and seeds can lead to unnecessary flare-ups and discomfort. Always prioritize safe food handling and preparation to ensure a positive culinary experience.

Frequently Asked Questions

Yes, tomato leaves and stems contain toxic alkaloids, primarily tomatine, which can cause digestive issues if ingested in large quantities. It is generally recommended to avoid eating them.

Unripe green tomatoes contain higher levels of tomatine compared to ripe red ones. While cooking can reduce the toxicity, consuming raw green tomatoes, especially in large amounts, can cause symptoms like nausea and stomach cramps.

For some individuals, stomach pain can be caused by the high acidity of tomatoes, which may trigger acid reflux. Others with sensitive digestive systems may react to the fibrous skins and seeds.

Individuals with a history of calcium oxalate kidney stones may be advised to moderate their tomato intake, particularly the seeds, as they contain oxalates. High potassium content can also be an issue for people with kidney disease.

The 'best' way depends on your health needs. Cooking tomatoes helps release more lycopene for better absorption and can make the skins softer for digestion. Raw tomatoes offer more vitamin C. For those with sensitivities, cooked and peeled tomatoes are often easier to digest.

To reduce the impact of tomato acidity, you can pair them with less acidic, alkaline foods like leafy greens or carrots. Cooking can also temper the acidity, and for those with GERD, it may be best to limit intake.

The core, or the tough white part where the stem attaches, is not toxic but is fibrous and can be unpleasant to eat due to its tough texture. Most chefs and cooks recommend removing the core before preparation for a better mouthfeel.