Myths About Food Fiber, Components, and Organs: From Texture and Digestion to Scientific Evidence

Myths About Food Fiber, Components, and Organs

The conclusion in one sentence

The health value of a food cannot be judged solely by how it feels when chewed, what it is called, or how tradition imagines it. We must distinguish scientific definitions, the substances actually present after human digestion, and the limits of what clinical evidence supports. PMID: 23729846

A coarse, tough texture does not mean more dietary fiber

The most important point in Professor Lin’s original article is that the everyday sensation of “fibrousness” should not be treated as nutritional “dietary fiber.” In medicine and nutrition, dietary fiber primarily comprises plant cell-wall polysaccharides and lignin that human digestive enzymes do not readily break down. It is a category defined by composition and digestibility, not by whether the teeth perceive a food as coarse, hard, woody, or stringy. PMID: 23729846

The structures of vegetable stems and strings may themselves contain cellulose or lignin, so they are not wholly unrelated to dietary fiber. What must be avoided is inferring fiber content from texture. Soft legumes can also be excellent sources of dietary fiber. If a food is puréed without filtering out the solids and pulp, it does not lose its original fiber merely because it no longer requires strenuous chewing. Professor Lin’s central clarification—that high-fiber foods need not be hard—therefore remains valid. PMID: 28303037

This distinction is not a matter of semantics. Higher dietary fiber intake is associated with lower risks of chronic disease and death. In practice, food choices should therefore be based on whole foods and genuine sources of dietary fiber, not on finding the bite that is hardest to chew. PMID: 30638909

Ingesting a component does not mean it reaches a target organ intact

In discussing collagen, Professor Lin identified a basic principle of digestive physiology: circulating amino acids rise after hydrolyzed collagen is taken orally, and ingested collagen should not be imagined as traveling intact and directly replenishing the skin or other tissues. PMID: 40523226

Scientific progress, however, also requires room for evidence to be updated. Professor Lin’s historical position in the original article regarding cosmetic benefits must not be rewritten. According to the updated literature retrieved today, systematic reviews and meta-analyses have reported benefits in randomized trials of oral collagen for skin photoaging and elasticity. It is therefore no longer appropriate to summarize every result as “absolutely impossible.” This does not mean that every product, dose, or marketing claim has been validated. It means that updated literature has changed the evidentiary limits of an absolute rejection. PMID: 40761858

Ejiao should be assessed by the same standard. Updated research in a specific population of women with symptoms described as blood deficiency found differences in some blood indices and symptoms. This is enough to narrow a claim that it “cannot work at all,” but not enough to extrapolate that it can enrich the blood in everyone or to endorse every traditional claim. PMID: 34707496

Plant-derived fatty acids are not equivalent to long-chain fatty acids

Plant-derived ALA can be converted to EPA in the human body, but this capacity is limited, and subsequent formation of DHA is even lower. It is therefore inaccurate to equate flaxseed oil directly with long-chain fatty acids from fish. Professor Lin’s warning about the limits of this conversion agrees with the literature. PMID: 16188209

On the other hand, current evidence calls for a more nuanced formulation than saying that ALA has no health effects of its own. Observational meta-analyses associate ALA intake with lower cardiovascular risk, while pooled randomized trials suggest that it may confer a modest benefit for some cardiovascular events. The more defensible conclusion is therefore that ALA cannot effectively replace EPA and DHA, but should not be dismissed as having no independent value. This boundary reflects updated literature; it does not rewrite Professor Lin’s own historical statement. PMID: 23076616

As to whether conversion efficiency necessarily declines with increasing age, ECU found no direct systematic evidence. The matter should therefore remain classified as having insufficient evidence, without further inference.

For taste and pungency, begin with plant chemistry

Miraculin from miracle fruit is a glycoprotein that makes acidic foods taste sweeter; this taste-modifying effect is pH-dependent. The literature supports Professor Lin’s account of the central phenomenon. However, the precise pH thresholds and the receptor sequence described in the original article as “occupy first, activate later” were not fully reproduced in this ECU summary. The overall direction can therefore be confirmed, but not every mechanistic detail should be treated as verified. PMID: 39358649

When cruciferous plants such as wasabi and horseradish are crushed, their cellular structures are disrupted, allowing myrosinase to contact glucosinolate and produce pungent isothiocyanates. This system also participates in plant defense. PMID: 26500669

Nevertheless, there remains a large leap from “an active substance can be formed experimentally” to “it can directly treat human disease.” Existing human research is insufficient to claim that isothiocyanates are a clinical anticancer therapy. Professor Lin did not inflate familiar antibacterial and anticancer claims into established medical effects, and that restraint is consistent with the literature. PMID: 40870788

Water bamboo is a food formed jointly by a plant and a fungus

Water bamboo is not an ordinary bamboo shoot. It is the edible swollen stem that forms when wild rice is affected by a smut fungus. The literature confirms this symbiotic relationship between plant and fungus and supports the general mechanism in which auxin- and cytokinin-related pathways drive tissue proliferation and enlargement. PMID: 33105697

Infected Asian cultivated wild rice is generally grown for its swollen edible stems, and normal heading and seed formation are disrupted. This cannot be extended into a claim that no wild rice plant can ever produce grain. Uninfected plants can still set seed, and their seed nutrition has been studied specifically. In light of current evidence, the absolute language in Professor Lin’s original article is best bounded as “cultivated forms generally do not set seed normally,” without rejecting his correct explanation of how water bamboo forms. PMID: 29958396

The smut fungus is more than a botanical curiosity. A case report describes hypersensitivity pneumonitis in a craft worker exposed to the associated spores, reminding us that certain occupational exposures should not be treated as ordinary contact with food. PMID: 8693452

“Waist ruler,” spleen, and pancreas: common names cannot replace anatomy

The spleen filters blood, removes red blood cells, and performs immune functions; it is not a digestive organ. Describing it simply as related to blood and lymphatic “circulation” points in roughly the right direction, but blood filtration, cellular clearance, and immune function are more precise terms. PMID: 41244599

The pancreas has both endocrine and exocrine functions: it secretes insulin to help regulate blood glucose and also releases digestive enzymes. This is why the pancreas and spleen cannot be conflated on the basis of appearance, vernacular food names, or market terminology. PMID: 42195419

Insulin was originally isolated from the pancreas, giving animal pancreases an important place in the history of medicine. PMID: 38540146

Pancreatic enzyme replacement products are still made from extracts of pig pancreas today. PMID: 42254859

Because the pancreas is rich in digestive enzymes, it also undergoes rapid autolysis after death. These findings support Professor Lin’s basic account of the pancreas’s medical uses and storage characteristics. PMID: 31239895

In anatomy, the kidney is a urinary organ, not a sex organ. Yet it would be too absolute to go further and say that kidney function has no clinical relationship whatsoever to sexual function. Men with end-stage kidney disease can experience sexual dysfunction and hormonal problems, showing that the two can be indirectly linked through vascular factors, hormones, and systemic disease. This does not equate the “kidney” of traditional Chinese medicine with the anatomical kidney; it separates organ classification from disease association. PMID: 42291847

How to read food-related health claims of this kind

First ask whether a term refers to texture, a common food name, a chemical component, or an anatomical organ. Then ask whether the evidence comes from a test tube, an animal, a human observational study, or a clinical trial. Finally, check whether the claim uses absolute terms such as “completely,” “always,” or “works for everyone” that go beyond the evidence. The popular-science context and historical position of Professor Lin’s original article should be preserved faithfully. When later research requires a conclusion to be narrowed, this should be stated explicitly as an update in the literature and an advance in science—not presented as though the professor himself later changed his position.