Foods That Age You? Trans Fats, Additives & Cooking Methods Explained

Some food patterns can affect inflammation, metabolic health, oxidative stress, and long-term disease risk. But the useful question is not “which foods ar…

Published November 23, 2024The Longevity Show

The trans fat story is supposed to be over. The FDA pulled partially hydrogenated oils from its generally-recognised-as-safe list in 2015, the formal removal landed in 2018, and use dropped sharply. Dr. Lin's point is that two routes stayed open. A product can still be labelled zero trans fat while carrying up to roughly 0.5 g per serving, which accumulates quickly across a processed diet — and high heat during frying or industrial processing converts unsaturated fats into trans fats regardless of what the label started as. The ban removed the ingredient, not the molecule.

This is part two of the series, and it moves from macronutrients to the industrial layer: trans fats, azo-dye colorants, emulsifiers and the advanced glycation end products your cooking method creates. The organising idea is that these compounds converge on a small number of shared mechanisms — membrane stiffening, endoplasmic reticulum stress, gut dysbiosis, oxidative stress and chronic low-grade inflammation — which is why the cumulative exposure matters more than any single item. Her framing is that it is not the soda or the chips or the burger; it is all of them adding into the same few pathways.

The evidence tiers here are uneven and the episode marks them. Much of the colorant and emulsifier data is mechanistic or from animal models — the polysorbate 80 neurological findings are specifically in aged mice, and the perinatal colorant work is animal research Dr. Lin says there is reason to extrapolate from rather than direct human evidence. She also revises her own prior position on emulsifiers on air. Part one covered saturated fats and added sugars; this instalment closes with the kitchen-level changes, including a shopping list and the cooking swaps that reduce AGE formation.

Before you watch

The zero-trans-fat label is a threshold, not a fact. In most countries a product can declare zero trans fat if it holds under roughly 0.5 g per serving, so a processed-heavy diet accumulates a meaningful load from foods that all read as clean. Dr. Lin's practical instruction is to read the ingredient list for partially hydrogenated oils rather than trusting the front-of-pack number, particularly outside jurisdictions with strong regulation.
Heat manufactures trans fats independently of the ban. Subjecting vegetable oils and unsaturated fats to high temperatures during frying or processing converts some of them into trans configurations — meaning even in countries where partially hydrogenated oils are prohibited, the compound can still arrive in the finished food. She also notes the naturally occurring version, produced in the guts of ruminants and present in small amounts in dairy and meat.
Trans fats do their damage by getting built into cell membranes. Beyond raising LDL and lowering HDL, they incorporate structurally and reduce membrane fluidity, which degrades the function of membrane-bound enzymes and receptors. In neurons, Dr. Lin's analogy is a phone with a cracked screen and a muffled speaker — the signal degrades rather than stops. Downstream she describes endoplasmic reticulum stress and impaired protein folding, accumulation of ceramides and diglycerides, insulin resistance, and telomere degradation that limits how many times a cell can safely divide. Fruit fly models have shown directly shortened lifespan alongside locomotor deficits and increased anxiety-like behaviour.
The azo-dye colorants come with names worth recognising on a label: tartrazine (FD&C Yellow No. 5, E102), sunset yellow (E110), quinoline yellow (E104), erythrosine (FD&C Red No. 3, E127), plus metanil yellow, malachite green and Sudan III. The mechanisms Dr. Lin describes are oxidative stress and neuroinflammation, measurable through markers such as MDA and reduced antioxidant enzyme activity, and mediated by pro-inflammatory signals including TNF-alpha and IL-6.
On dyes and children's behaviour, the episode's position is that synthetic colourings are associated with worsening ADHD symptoms, acting through the same oxidative stress and neuroinflammation pathways rather than through any distinct mechanism. She extends this to memory and processing speed, mood, and — in animal models specifically — neurodevelopmental toxicity via mitochondria-mediated apoptosis, including perinatal exposures producing altered reflexes and locomotor behaviour in offspring. She flags the animal-model boundary explicitly rather than eliding it.
Emulsifiers are where Dr. Lin publicly changes her mind. She describes having been broadly fine with them, and says the research was enough to put her off. The named compounds are polysorbate 80 (Tween 80), carboxymethylcellulose, soy and egg lecithin, mono- and diglycerides, carrageenan, and the gums — guar, xanthan and relatives. Sodium stearoyl lactylate keeps bread from staling; lecithin makes chocolate melt smoothly.
The polysorbate 80 findings she cites are specifically in aged mice, and she says so. In that model it increased pathological protein deposition, disrupted the blood-brain barrier, activated microglia and neurotoxic astrocytes, and induced gut dysbiosis contributing to cognitive decline through altered bile acid metabolism and neuroinflammation — with more pronounced inflammatory responses in aged animals than younger ones. Polysorbate 80 and carboxymethylcellulose have both been implicated in low-grade intestinal inflammation, metabolic syndrome and liver lipid accumulation.
The fat-free yogurt problem is the most useful shopping consequence. Removing fat costs mouthfeel, so it gets replaced with emulsifiers — which is why some health advice steers away from fat-free dairy. Her stated ideal is lower fat and no emulsifiers, while conceding that requires reading ingredient lists. Her related tell: a separated nut butter you have to stir is likely the better one, precisely because it lacks the emulsifiers holding the smooth version together. Gluten-free baked goods are a similar trap, since gums substitute for the elasticity gluten provided.
Advanced glycation end products are created by your cooking method, not just your groceries. They form via the Maillard reaction when sugars bind proteins or fats under high dry heat — grilling, roasting, frying — and once eaten, accumulate in tissue. Mechanistically Dr. Lin describes AGEs binding the RAGE receptor to upregulate pro-inflammatory cytokines, chemokines and adhesion molecules, and driving reactive oxygen species through NADPH oxidases and mitochondrial dysfunction, producing endothelial dysfunction and accelerated atherosclerosis.
The highest-AGE foods are largely the browned ones: red meat, poultry and processed meats cooked at high temperature; baked goods, where the Maillard browning is the point; high-fat dairy such as cheese and butter, especially when processed or heated; fried foods and battered fried items; and ultra-processed products generally, because industrial processing is itself high-temperature cooking most people do not count as cooking. Eggs carry some but considerably less. The swaps are steaming, poaching, or baking at lower temperatures. Dr. Lin notes her great-uncle, a neurologist, was telling the family not to eat the brown or burned bits decades ago — with the right instinct and the wrong mechanism, since he attributed it all to cancer.
Her label heuristic is a count, not a chemistry test. Aim first for foods that need no nutrition label at all, and when one is required, look for three to five ingredients maximum. She is honest that the popular advice to avoid anything you cannot pronounce breaks down in practice, offering instead that if the list reads like a chemistry textbook it is probably not for you. The cooking-at-home argument gets a personal footnote: a gas main break left her New York City block without gas for three days, and she learned to use an air fryer for fish and vegetables as a result.

Chapters

Questions

Trans fats were banned — why do I still need to worry about them?

Because two routes remained open after the ban. The FDA declared partially hydrogenated oils no longer generally recognised as safe in 2015, with formal removal by 2018, and usage fell sharply. But in most countries a product can still be labelled zero trans fat while containing up to about 0.5 g per serving, and across a processed-food diet those fractions add up. Separately, subjecting unsaturated vegetable oils to high heat during frying or industrial processing generates trans fats directly, so they can appear in food that never had partially hydrogenated oil added. Dr. Lin's advice is to read the ingredient list rather than the front-of-pack claim.

What do emulsifiers actually do to your gut?

The concern is dysbiosis and barrier integrity. Dr. Lin describes polysorbate 80 and carboxymethylcellulose as promoting low-grade intestinal inflammation and disrupting the gut microbiome, which in turn is linked to increased intestinal permeability — the phenomenon commonly called leaky gut — allowing material into the bloodstream that raises systemic inflammation. In aged mice specifically, polysorbate 80 also disrupted the blood-brain barrier, activated microglia and neurotoxic astrocytes, and contributed to cognitive decline through altered bile acid metabolism. She is clear that the neurological findings come from aged animal models rather than human trials, and she notes this evidence changed her own prior view.

Which foods have the most advanced glycation end products?

The browned ones. AGEs form through the Maillard reaction when sugar binds protein or fat under high dry heat, so the highest levels are in red meat, poultry and processed meats cooked by grilling or frying; in baked goods, where browning is the objective; in high-fat dairy such as cheese and butter, particularly once processed or heated; in fried and battered foods; and in ultra-processed products generally, since industrial processing applies high temperatures most people do not think of as cooking. Eggs contain some, but far less than meats or baked goods. Switching to steaming, poaching or lower-temperature baking reduces formation substantially.

Are artificial food dyes really linked to ADHD?

The episode's position is that synthetic food colourings are associated with worsening ADHD symptoms in children, and that the mechanism is not special to behaviour — it runs through the same oxidative stress and neuroinflammation implicated in the dyes' other effects, mediated by signals such as TNF-alpha and IL-6. Dr. Lin extends the concern to memory and processing speed and to mood, and describes neurodevelopmental toxicity including perinatal exposures altering reflexes and locomotor behaviour. It is worth noting the boundary she draws herself: a substantial part of this is animal-model evidence that she believes there is reason to extrapolate from, not direct human trial data.

Is fat-free yogurt better or worse than full-fat?

Dr. Lin's answer is that the choice is usually a false one, because removing the fat means adding something back. Fat carries mouthfeel, so fat-free and low-fat dairy commonly gain emulsifiers to restore smoothness — which is the reason some health commentators steer people away from fat-free versions specifically. Her stated ideal is lower fat and no emulsifiers or additives, which in practice means reading the ingredient list rather than the front of the tub. She applies the same logic to nut butter: the separated version you have to stir is likely the better one, because the smooth version is smooth for a reason.

How do I read a food label without becoming a chemist?

Dr. Lin's rule is to count rather than analyse. Aim first for foods that do not need a nutrition label at all — single-ingredient whole foods — and when a label is unavoidable, look for three to five ingredients maximum. She is candid that the familiar advice to avoid anything unpronounceable does not really hold up, since plenty of harmless things are hard to pronounce and plenty of people pronounce things differently; her substitute is that if the list reads like a chemistry textbook, it is probably not worth eating. The specific items she suggests scanning for are partially hydrogenated oils, the azo-dye colorants, and emulsifiers such as polysorbate 80, carboxymethylcellulose and carrageenan.

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