– What are antioxidants?


I see them advertised in almost every drink in the store. What are they? What do they actually do?

In: Biology

I believe they neutralize something called free radicals on our bodies. Free radicals are unstable molecules (?) because of like some uneven carbon charge or something. So antioxidants come in and make everything stable so that we’re all good. Free radicals, because they are unstable can be cancer causing.

Disclaimer: this information is solely based off of what I remember from orgo chem from like 3+ years ago

Antioxidants are compounds that were thought bind to “free radicals” and render them inert. In the same way iron “oxidizes” and turns to rust, compounds within the body degrade over time, releasing free radicals, which cause cell damage because they are looking for an atom to complete their outer layer of electrons. Free radicals can be absorbed or ingested, as well as created within the body. A lot of airborne pollutants increase free radicals. Antioxidants were thought to bind to these free radicals and allow them to be exhaled or excreted. This science has not been proven to have any health benefit, however. Foods that are high in antioxidants are generally healthful, but the antioxidants themselves have not been proven to have health benefits.

Biology is a nasty business. It’s all about chemical reactions, and chemical reactions, especially covalent ones, are all about the ionic states of atoms and molecules. Every atom has a “standard” number of electrons, which is equal to its number of protons. Hydrogen for example has one electron. Atoms hate to have certain numbers of electrons, so they seek to find ways to fill in the gap. The numbers of electrons atoms like to have is standardised and arranged into “shells”, relatively speaking. The first shell is 2 electrons – any atom with fewer than 2 electrons will try to get to having 2 electrons. The next shell can contain 8 electrons, for a total of 10 electrons. Any atom with fewer than 10 electrons but more than 2 will try to get to having 10 electrons overall. Atoms are more “comfortable” when they have complete shells.

Covalent bonding is really important in biology, it’s how a lot of things happen and it determines most of the structure of proteins and so forth. It also determines the structure of DNA. Covalent bonding works as follows: Two atoms that both have incomplete shells notice each other and say “Hey, I have this electron and you have that electron. Wanna share them?” This lets atoms feel like they have the right number of electrons, and atoms kinda chill next to each other and move with each other when they’re sharing electrons like this.

Many metals have too many electrons, but are a long way away from completing the next shell. Instead, they seek to *lose* electrons. Atoms like this engage in ionic bonding. Rather than sharing electrons so that both atoms get full shells, these ions simply try to *get rid* of electrons, so that they have fewer shells, but all their shells are stable. When an atom gives away an electron like this, it gains a net positive charge, because it has more protons than electrons. Meanwhile, the ion that accepts the spare electron to complete its shell gains a net negative charge, because it has more electrons than protons. Normally, ionic bonding like this is pretty cool. They might become a crystal lattice, they might end up in solution, the positive and negative ions all floating around happy with their complete outer shells and electrical charge.

Then there’s free radicals. Free radicals are kind of like cellular terrorists. These molecules have an improper number of electrons, and really want to find something to glue themselves to. Free radicals are created by natural biological processes, since a lot of these processes deal with moving around electrons and sometimes some just end up in free radicals. Sometimes these extra electrons are even a vital component of biological processes – they’re often intermediary steps in important chemical reactions.

Free radicals really want to complete and stabilise their shells, so they float around and bump into stuff until they find some way to deal with it – typically by bonding to something that didn’t want to be bonded to. This can cause chain reactions which ultimately destabilise or damage molecules, which can do lots of different things, including changing its shape or destroying it completely. Shape is really important for function in biology, so shape changing is bad. The worst thing a free radical can typically do is damage DNA. if it passes its electron into DNA, the DNA can mutate, and that can lead to cancer. Cancer sucks, so the body likes to fight it. It likes to do this by preventing their formation. Free radicals often form as a result of a process called oxidation. Antioxidants simply prevent this oxidation from occurring.