Biochemistry Myths (Chemicals Are Bad, Natural Is Safe…)

Walk down the aisle of any supermarket or scroll through a wellness feed and you’ll meet a whole vocabulary that sounds scientific but isn’t: “chemical-free”, “toxins”, “detox”, “alkalising”, “natural goodness”. Many of these claims rest on misunderstandings of basic biochemistry. This guide takes nine of the most common and explains, with real chemistry, what’s going on.

Myth 1: “This product is chemical-free”

The chemistry: everything made of matter is made of chemicals. Water is a chemical (H₂O). So is the oxygen you breathe, the sugar in fruit and the DNA in your cells. A banana contains hundreds of different compounds, including some with intimidating names such as 3-methylbutyl acetate — the molecule largely responsible for banana smell.

What advertisers usually mean is “free of synthetic additives we think you’ll worry about”. That may or may not be a good thing, but “chemical-free” is literally impossible. The only truly chemical-free product is an empty box — and even that is made of chemicals.

Myth 2: “Natural is safe, synthetic is dangerous”

The chemistry: whether a compound was made by a plant or in a factory tells you nothing about its safety. What matters is its structure and its dose. Some of the most toxic substances known are natural:

• Botulinum toxin, made by a bacterium, is lethal in quantities of well under a microgram.
• Ricin comes from castor beans.
• Solanine in green potatoes, cyanide-releasing compounds in bitter almonds and apricot kernels, and aflatoxins from moulds on stored nuts and grain are all natural.

Meanwhile, a synthetic molecule is identical to the same molecule made by nature. The vitamin C made in a factory is exactly the same compound, ascorbic acid, as the vitamin C in an orange (see vitamin C chemistry). Your body can’t tell where it came from — and neither can a laboratory instrument, except in rare cases where isotope ratios differ slightly.

Myth 3: “Toxins build up in your body and need a detox”

The chemistry: your body already has a sophisticated detoxification system. The liver uses enzymes to oxidise foreign molecules and then attach polar groups to them, making them water-soluble (see pharmacology basics). The kidneys filter the blood and excrete water-soluble waste in urine. The lungs remove carbon dioxide, and the gut excretes other waste.

Detox teas, foot pads and juice cleanses rarely name which “toxin” they remove, and there’s no good evidence they remove any. Foot pads that turn brown overnight are reacting with moisture from sweat. If your liver or kidneys genuinely fail, the treatment is medical — dialysis or a transplant — not a smoothie.

Myth 4: “An alkaline diet changes your blood pH”

The chemistry: blood pH is held between about 7.35 and 7.45 by powerful buffer systems, mainly the carbonic acid–hydrogencarbonate buffer:

CO₂ + H₂O ⇌ H₂CO₃ ⇌ H⁺ + HCO₃⁻

If extra acid enters the blood, HCO₃⁻ mops up the H⁺; the lungs breathe out the extra CO₂ and the kidneys adjust how much acid and hydrogencarbonate they excrete (see the blood buffer system). Food can change the pH of your urine, because the kidneys dump the excess, but not the pH of your blood. If blood pH does move outside its normal range, it’s a medical emergency (acidosis or alkalosis), caused by conditions such as diabetic ketoacidosis or lung disease, not by lemons or steak.

A side note: lemons are acidic (pH about 2), but alkaline-diet charts often list them as “alkalising” because of the minerals left after metabolism. That’s another hint the idea isn’t about blood.

Myth 5: “Sugar from fruit is different from table sugar”

The chemistry: table sugar is sucrose, a disaccharide made of one glucose and one fructose. Fruit contains a mixture of glucose, fructose and sucrose. Once digested, the sucrose is split into glucose and fructose — the same molecules as those in fruit.

What is different about whole fruit is the package: water, fibre, vitamins and minerals, which slow down how fast the sugar is absorbed and make it harder to eat large amounts. So fruit is generally a healthier source of sugar, but not because its sugar molecules are special. Fruit juice, without the fibre, behaves much more like sugary drinks. For the details, see what happens to sugar in your body.

Myth 6: “You are what you eat — literally”

The chemistry: eating collagen doesn’t send collagen to your skin, and eating brain doesn’t improve your brain. Digestion breaks proteins into amino acids, starch into glucose and fats into fatty acids and glycerol (see the chemistry of digestion). Your cells then rebuild their own molecules from these building blocks, following instructions in your DNA.

So the phrase is true in a looser sense — your body is built from atoms that came from your food — but the molecules themselves are taken apart first. A protein in food has no memory of where it came from once it’s digested.

Myth 7: “Chemicals with long names are bad for you”

The chemistry: chemical names describe structure, not danger. The systematic name for vitamin C is (5R)-5-[(1S)-1,2-dihydroxyethyl]-3,4-dihydroxyfuran-2(5H)-one. Riboflavin (vitamin B₂) is added to foods under the code E101. Many E-numbers are compounds found naturally in food: E300 is ascorbic acid, E330 is citric acid (from citrus fruits), E948 is oxygen.

A short name isn’t a safety guarantee either. “Arsenic” is short. Judge a substance by what it does and at what dose, not by how hard it is to pronounce.

Myth 8: “Organic food contains no pesticides and is chemically superior”

The chemistry: “organic” in farming is a legal standard about how food is grown. Organic farmers can use certain approved pesticides, including some based on natural compounds or copper salts. Studies comparing nutrients in organic and conventional crops generally find small, inconsistent differences. There are reasonable arguments about farming practices and the environment, but organic vegetables aren’t made of different kinds of molecules.

There’s also a naming confusion: in chemistry, organic means “carbon-based”. Both organic and conventional carrots are full of organic compounds. So are petrol and plastic.

Myth 9: “If a little is good, more is better”

The chemistry: almost every useful substance has a harmful dose. The idea that “the dose makes the poison” dates back to Paracelsus in the sixteenth century, and it still holds:

• Water: drinking several litres very quickly can dilute blood sodium dangerously (hyponatraemia).
• Vitamin A: essential for vision, but very large doses can damage the liver and cause birth defects. Because it’s fat-soluble, it’s stored rather than excreted.
• Vitamin D: too much raises blood calcium to harmful levels (see vitamin D chemistry).
• Iron: accidental overdose of iron tablets is a known cause of serious poisoning in young children (see iron in the body).

Water-soluble vitamins such as vitamin C are less risky because excess is excreted in urine, but megadoses still have side effects. Balanced nutrients, not maximum nutrients, are the goal.

Why these myths are so persistent

Most of them share a pattern: a real word (“toxin”, “alkaline”, “natural”) used in a vague way, a grain of truth (some toxins exist; some foods change urine pH), and a product to sell. Chemistry education is the best defence. When you meet a claim, ask:

1. Which specific molecule is involved?
2. What dose is being talked about?
3. What does the body already do with it?
4. Is there evidence from controlled studies, not just testimonials?

Key takeaways

• Everything is chemicals; safety depends on structure and dose, not origin.
• The liver and kidneys already detoxify; commercial “detoxes” don’t have good evidence.
• Blood pH is buffered tightly; diet changes urine pH, not blood pH.
• Digestion breaks food down into building blocks; eaten molecules don’t go straight to the matching body part.
• More isn’t always better — even vitamins and water are harmful in excess.

To learn how the body really handles molecules, start with biomolecules: an overview and elements in the human body.