Tomatoes are one of the most popular and widely consumed vegetables worldwide. However, there are conflicting claims regarding the health effects and safety of tomato seeds, which are usually discarded when tomatoes are prepared or cooked. Some sources raise concerns that substances like solanine or lectins in tomato seeds may be toxic or carcinogenic.
This thorough article will analyze the scientific evidence behind tomato seed safety and any potential cancer risks. Read on to learn about the nutritional profile of tomato seeds, their health effects, and whether the consumption of tomato seeds is associated with increased cancer risk.

An Overview of Tomato Seeds

The tomato (Solanum lycopersicum) is a flowering plant in the nightshade family. Inside each tomato fruit are numerous seeds encased in a gelatinous sack. Most people discard the seeds when preparing tomatoes, but the seeds are edible.
Tomato seeds are highly concentrated sources of nutrients and beneficial plant compounds compared to the flesh. Just one ounce (28 grams) of dried tomato seeds contains about:

• 25-30mg of vitamin E - over 100% of the RDI
• 2-3g of protein
• 2g of fiber
• Iron, phosphorus, magnesium, zinc and copper
• Potent antioxidants like lycopene and phytosterols

Additionally, tomato seeds consist of 25-30% oil containing essential fatty acids like linoleic, oleic and alpha-linolenic acids. However, there are also some potentially harmful substances found in tomato seeds.

Beneficial Compounds in Tomato Seeds

The nutrients and antioxidants in tomato seeds provide significant health benefits. Here is a summary of the major beneficial substances:

Vitamin E - A potent antioxidant that protects cells from damage and inflammation. It supports healthy skin, immune function, and circulation.

1. Lycopene - A carotenoid antioxidant that gives tomatoes their red color. It has strong anti-cancer and health-promoting activities.
2. Phytosterols - Plant compounds that lower LDL cholesterol and reduce heart disease risk. They also have anti-cancer benefits.
3. Polyphenols - Antioxidants that fight oxidative stress linked to chronic diseases like diabetes and neurodegeneration.
4. Fiber - Promotes digestive health, regularity, and feeds the good bacteria in the gut microbiome.
5. Essential Fatty Acids - Omega-3 and omega-6 fats support skin, eye, nerve and brain health. They reduce inflammation.
6. Magnesium & Potassium - Important minerals that are involved in muscle, nerve and cardiovascular function.

The combination of all these compounds makes tomato seeds nutritional powerhouses when eaten. But some people are concerned about potentially harmful substances found in the seeds as well.

Potentially Harmful Compounds

While tomato seeds have a stellar nutritional profile, they also contain some antinutrients and toxins at low levels, including:

1. Solanine - A glycoalkaloid toxin found in tomatoes and nightshade plants. In excess, it can be neurotoxic and irritating.
2. Lectins - Proteins that bind carbohydrates and can damage the gut lining at high doses. Found in many plant foods.
3. Oxalates - Compounds that interfere with mineral absorption and may cause kidney stones when overconsumed.
4. Saponins - Bitter compounds with hemolytic activity but also strong anti-cancer effects.

However, these compounds exist in very low concentrations in tomato seeds, and pose minimal risk from typical dietary exposure. But some people think they may cause harm if consumed regularly.

Do Tomato Seeds Cause Cancer? Evaluating the Evidence

There are two primary concerns that are often raised regarding the potential cancer risk from eating tomato seeds regularly:

• Solanine toxicity
• Lectin content

However, extensive research shows neither solanine nor lectins in tomato seeds have any carcinogenic or tumor-promoting activity. Let’s analyze the science behind both of these concerns:

Solanine Toxicity and Cancer Risk

• The major toxic compound in tomato seeds is solanine, a glycoalkaloid. In high doses, solanine can inhibit cholinesterase enzymes and be neurotoxic.
• Many glycoalkaloids have been found to be cytotoxic against cancer cells in test tube studies. However, human studies show that normal consumption of solanine does not increase cancer risk.
• A 2020 review of the anticancer effects of glycoalkaloids found that solanine does not enhance tumorigenesis at normal dietary intakes. Doses up to 4-5mg/kg body weight per day were not considered toxic or carcinogenic in humans.
• Tomato seeds only contain about 5-10mg per 100g of solanine. A 60kg (132lb) adult would need to eat around 1.5kg of dried tomato seeds to reach the 4mg/kg solanine threshold for toxicity.
• Therefore, the small amounts of solanine in tomato seeds are far too low to cause cancer or toxicity when seeds are eaten in normal food amounts.

Lectin Harm and Cancer

• Lectins like tomatine in tomatoes can damage the gut lining at extremely high intakes. This led to speculation that lectins may promote cancer development.
• However, human studies have not found correlations between normal lectin intake and any cancers. Research shows dietary lectins are safely degraded, poorly absorbed from the gut, and do not exhibit carcinogenic effects.
• A review of the health effects of dietary lectins concluded they do not cause or aggravate cancer at normal intakes. Extremely high lectin doses are required to initiate DNA damage responses or apoptosis in human cells.
• Tomato seeds only have about 0.1-1% tomatine by weight. Typical consumption of tomato seeds is not high enough for its lectin content to demonstrate toxicity, let alone increase cancer risk.

Do Tomato Seeds Protect Against Cancer?

Not only is there no evidence that normal ingestion of tomato seeds causes cancer, but emerging research suggests tomato seeds may actually help protect against several types of cancer:

Prostate Cancer