Food Safety Myths: An Evidence-Based Reading of Glycoalkaloids, Leftovers, Plastics, and Supplements

Food Safety Myths: An Evidence-Based Reading of Glycoalkaloids, Leftovers, Plastics, and Supplements

Bottom line

Food safety is not about crudely sorting foods into “toxic” and “nontoxic.” It is about determining whether a hazard creates a meaningful risk in light of the ingredient’s identity, ripeness, dose, handling, actual exposure, and evidence in humans. PMID: 42422975

Black nightshade leaves and glycoalkaloids: cooking is not a universal guarantee

In his original article on the claim that “black nightshade leaves must be cooked before eating,” Professor Ching-Shun Lin identified the key issue: the presence of a natural toxin is not determined by a simple raw-versus-cooked distinction. Black nightshade does contain toxic glycoalkaloids, and excessive exposure may cause gastrointestinal and neurologic symptoms. It therefore should not be treated as an ordinary vegetable that is safe under all conditions. PMID: 41819152

Glycoalkaloids are relatively heat-stable, so ordinary heating alone cannot guarantee that risk will fall to zero. The literature also shows that processing may reduce their concentration in food, but this does not mean that the molecules are necessarily destroyed completely. The mechanistic core of Professor Lin’s rejection of the claim that “cooking always makes it safe” therefore remains valid. If, however, “boiling has no effect whatsoever” is presented as an absolute fact, updated literature and scientific progress call for a narrower formulation: ordinary cooking may not reliably eliminate the risk. PMID: 42221871

Membership in the same botanical family does not imply identical conditions of toxicity. Tomatoes are primarily relevant for tomatine; their constituents should not all be loosely labeled solanine. Tomatine is transformed during ripening, so the risk profiles of ripe red tomatoes and unripe green tomatoes should not be conflated. Ripe tomatoes can be eaten raw, and the claim that they are toxic merely because they have not been cooked is inconsistent with current literature. PMID: 39970214

Sprouted potatoes are a different situation that warrants caution. Glycoalkaloids may be concentrated in the skin, and sprouting or other signs of deterioration cannot be dismissed by saying that the potato has been cooked. Avoiding suspect ingredients is more reliable than expecting household cooking to detoxify them completely. PMID: 38890940

From hazard to risk: detection does not mean inevitable disease

Detecting a substance proves only that it is present; it does not automatically tell us whether it will harm a person. Food-risk assessment must also consider chemical form, concentration, intake, bioaccessibility, and exposure context. Total arsenic in a food, for example, cannot simply be treated as harmful inorganic arsenic. Nor can the organic arsenic commonly found in seafood support a straight-line inference that “shrimp plus vitamins equals arsenic poison.” PMID: 41897790

Likewise, removing fish skin does not produce a fixed reduction in every heavy metal. The effect varies by fish species and contaminant. Applying one appealing percentage to all fish turns a conditional result into a supposed universal law. PMID: 23186633

Professor Lin has repeatedly challenged the inference that if something shows harm at a high dose, in an animal, or under in vitro conditions, ordinary dietary exposure must cause disease. This does not deny the hazard; it requires actual human exposure to be restored to the assessment. A hazard asks whether something can cause harm, whereas risk asks how likely that harm is under a particular use and level of exposure. PMID: 40786114

Leftovers, microwaves, and single cases: sequence in time does not identify a source

Media reports often rewrite “became ill after eating something” as “became ill because of that food.” The epidemiology of meningococcal disease centers on person-to-person transmission, carriage, and close-contact clusters, but that general knowledge still cannot replace testing of food from a specific case, cultures from contacts, or strain comparison. PMID: 35455366

Professor Lin therefore had an evidentiary basis for questioning media reports that summarily blamed leftovers. Yet the available case information is likewise insufficient to present “the leftovers were completely unrelated” as an established fact. The most accurate statement is that the case occurred, but a timeline of symptom onset neither confirmed nor ruled out the source of infection. PMID: 33704941

Properly stored vegetables that are reheated and eaten by adults cannot be declared inevitably carcinogenic merely because they are “overnight” leftovers. Existing evidence also does not support reducing vegetable nitrate and reheating to a claim of inevitable harm. This does not mean that every scenario involving storage, contamination, or holding conditions is safe; it means rejecting sweeping alarm in the absence of exposure data. PMID: 40243642

A microwave oven should not be treated as a special “cancer machine,” either. A specific beef experiment did not find microwave cooking more likely than frying or broiling to produce detectable mutagenic activity. Microwave pretreatment may instead reduce the heterocyclic amines formed during subsequent frying. Nutrient retention varies with the food and heating conditions, so one cannot categorically claim that microwaving destroys all nutrients. PMID: 7030472

Plastics, microplastics, and packaging: neither exaggeration nor minimization

Microplastics research is advancing rapidly. An early assessment that direct causal evidence in humans was not yet available cannot be rewritten as proof of complete harmlessness. Micro- and nanoplastics have been observed in human arterial plaques and associated with subsequent events, but this remains an association, not causation established by a single study. PMID: 38446676

Scientific progress also requires some older statements to be updated. Plastic bottles themselves can be a source of microplastics in bottled water, so exposure can no longer be attributed entirely to the environment and source water. This reflects updated literature; it does not rewrite a historical article as though Professor Lin himself had advanced the new conclusion. PMID: 41600643

For contact between hot food and plastic, the direction of evidence is clearer. Higher temperatures can increase migration of some plastic-related chemicals, while fat, salt, and acid in food may also alter leaching. “Heat-resistant material” is therefore not synonymous with “no migration under any hot-food condition.” In practice, unnecessary high-temperature contact with plastic can reasonably be reduced. PMID: 40457048

Bisphenols in can linings should be judged on the same scale. Detecting a substance does not justify declaring that every can of tomatoes will cause disease, but newer risk assessments are more cautious than the earlier language of “ongoing controversy.” A reasonable approach is to manage cumulative exposure, rather than choose between “never eat it” and “ignore it completely.” PMID: 41897826

Natural products, health products, and food therapy: examine both efficacy and safety

“Natural” is neither a guarantee of efficacy nor a certificate of safety. Eating placenta has no established clinical benefit in humans, and encapsulation may not eliminate infectious agents. It is inappropriate to package traditional use or animal research directly as evidence of human benefit. PMID: 28859955

Dietary supplements are associated with documented adverse events, and older adults who use supplements along with prescription drugs must also be alert to specific interactions. For healthy adults eating a balanced diet, routine vitamin or mineral supplementation has no clear universal benefit for preventing cardiovascular disease or cancer. People with a deficiency or a particular indication should supplement according to their clinical circumstances; this does not justify the opposite claim that every form of supplementation is ineffective. PMID: 35727272

Antioxidant supplements, in particular, should not be understood as a case of “more is better.” Pooled findings from some large trials suggest that certain antioxidants may increase mortality risk, but that does not mean every vitamin, every dose, and every person will have the same outcome. The direction of Professor Lin’s warning about high-dose supplementation is supported, while its scope must still be stated clearly. PMID: 22419320

Food–drug interactions likewise resist blanket rules. Grapefruit and related citrus juices can alter exposure to some medicines, but not every drug is affected. Statins also differ from one another. Patients should verify the specific medication and medical instructions rather than permanently prohibiting every related citrus fruit on their own. PMID: 26478732

How to read food-safety news

When a headline says “toxic,” “carcinogenic,” “detoxifying,” or “incompatible foods,” ask in sequence: were the subjects humans or animals? Was the finding a detection, an association, or a causal effect after an intervention? Was the exposure close to an ordinary diet? Were the species, part, ripeness, and processing of the food the same? Was source attribution performed for the case? When these conditions are missing, the certainty of the headline usually exceeds the evidence.

Persimmons are a classic example. Current medical literature supports that unripe, high-tannin persimmons can form bezoars and may require endoscopic management. This is a specific mechanism and is not the same as a claim that persimmons and crab are “incompatible” and generate a mysterious toxin. Cola may be one component of some treatment pathways for phytobezoars, but this does not mean that people should replace diagnosis and treatment with a soft drink on their own. PMID: 23252775

The most robust conclusion is often neither “absolutely safe” nor “definitely toxic.” It states clearly what is known, what remains unknown, and which people and circumstances call for greater caution. This approach best reflects the fact-checking spirit of Professor Lin’s original work: fear should not replace evidence, and “not yet proven” should not be quietly substituted with “proven harmless.”