Written by
Louise W Lu, PhD, MPH, BMLS
Written/Reviewed by
Alexandra V Goldberg, Registered Dietitian
In one of our recent nutrition consultations, a mother asked us this question:
“My child doesn't like swallowing capsules and always struggles with taking vitamins. There are gummy-type vitamins on the market now that look like candy—he loves them. Can I use those instead?”
We’ve heard this question more times than we can count. And yes, have you ever found yourself tempted by these “gummy-style” vitamins?
Colourful, fruity, chewable without water—they even resemble the gummy candies we loved as kids. Many women, children, and even adults who dislike swallowing pills have fallen in love with this “tastier way” of supplementing.
Especially gummy vitamins—they may be the most oxidation-prone type of all.
What Is Oxidation?
In simple terms, oxidation is the process of nutrients breaking down, which can render active ingredients ineffective—or worse, harmful. Oxidation can:
- Destroy the vitamins themselves and cause nutrient loss
- Produce free radicals and degradation byproducts that may harm your health
- Alter texture or flavour over time—turning gummies hard or oily without you noticing
What’s most concerning? They can still taste sweet and smell fruity, while no longer delivering the benefits they promise.
In this article, we’ll cover:
- What is supplement “oxidation” exactly?
- Why are gummies especially vulnerable?
- How can you choose and store them safely?
Jump to Sections:
Why Do Supplements "Oxidise"?
Oxidation is one of the most common chemical reactions in our daily lives. Rusting metal is oxidation. A cut apple turning brown is oxidation. Cooking oil going rancid over time is also oxidation. In supplements, oxidation refers to the structural changes that occur when nutrients are exposed to air, light, moisture, or heat.
In simple terms, once-effective ingredients may degrade and turn into "inactive" or even "harmful" compounds.
💡 Oxidation can lead to:
- Reduced or completely lost nutrient activity
- Formation of free radicals and oxidation by-products, which may irritate the gut or damage cells
- Visible changes — such as discolouration, oil leakage, hardening, or bitter taste
Some of the most oxidation-prone ingredients in supplements include fat-soluble vitamins (A, D, E, K), Omega-3 fish oil, and natural carotenoids like β-carotene. Once oxidised, even if taken regularly, they may no longer deliver the intended health benefits.
Here’s a comparison of some commonly oxidised ingredients:
(📱Mobile users: Scroll left and right to view the full table)
| Ingredient | Why It Oxidises Easily | Changes After Oxidation |
|---|---|---|
| Vitamin A | Highly unstable, breaks down easily under light | Discolours, loses effectiveness, hard to absorb |
| Vitamin E | Although an antioxidant, it oxidises easily itself | Capsules darken, efficacy declines |
| Fish Oil (Omega-3) | EPA/DHA are highly unstable and oxidise quickly in air | Develops fishy odour, causes reflux, forms irritating oxidised by-products |
| β-Carotene | Extremely sensitive to light and oxygen | Fades in colour, nearly no nutritional value |
This is why high-quality supplements often come in sealed softgel capsules, light-protective packaging, nitrogen-filled bottles, or require cold-chain transport to slow down oxidation.
Take Vitamin E, for example. It’s an antioxidant itself, yet extremely prone to oxidation. If stored improperly, the capsule may darken, the inside may become sticky or smelly — signs that the active compound has broken down.
For instance: Omega-3 fish oil is extremely sensitive to oxidation. When fresh, it should be almost tasteless and odourless. But if the bottle is opened frequently and exposed to air, EPA and DHA can degrade rapidly, leading to a fishy smell and unpleasant reflux. Worse, they may release small inflammatory oxidised molecules that can harm the body instead of helping it.
So avoid fish oil drops in bottles — they’re a terrible idea.
Once opened, fish oil in liquid form is nearly impossible to keep stable, even when refrigerated. Oxidation is almost guaranteed.
Section 2｜Why Are Gummies Especially Prone to Problems?
Compared to capsules, tablets, or powders, vitamin gummies are far more prone to oxidation and degradation after packaging. This is mainly due to the following four structural issues:
📌 You can scroll to view the full table
| Structural Risk | Why It Affects Stability |
|---|---|
| High Moisture Content | The pectin or gelatin base in gummies contains about 15% water—much higher than tablets (<5%). This significantly increases the degradation rate of some vitamins like vitamin C and B-complex. |
| High Sugar Content | Sugar acts as a “reducing agent,” accelerating oxidation, especially in products containing iron, copper, or vitamin C. |
| Prone to Melting and Moisture Absorption | In hot or humid conditions, gummies tend to leak oil, crystallize sugar, soften, harden, or clump together—common signs of oxidation. |
| Poor Packaging Seals | Most gummies use standard caps without nitrogen flushing or light protection. Once opened, they are more likely to absorb moisture and oxidize. |
We've opened and tested several popular gummy products. Many of them appeared fine, but already showed taste changes, clumping, or sugar leakage. You may not notice—but active ingredient levels could have significantly dropped.
“The gummy format relies heavily on sugar and gelatin to hold its shape—both of which are unfriendly to vitamin stability.”
Take special note: The more unstable nutrients a gummy contains (such as fish oil, vitamin C, B vitamins, iron, or folate), the more likely it will degrade prematurely.
👉 Our advice: If you must choose gummies, go for professional brands with a single active ingredient, low moisture, and light-protected, nitrogen-sealed packaging.
03｜How to Tell If a Supplement Has Oxidised? Which Ingredients Are Most Vulnerable?
How can you tell if a supplement has oxidised?
- Appearance: darkening, cloudiness, oil leakage, stickiness, or misshaping
- Smell: a stale “frying oil” odour, or something like an unwashed deep fryer
- Taste: formerly light and fruity now tastes bitter, sour, or unpleasant
💡 Note: Not all oxidation can be detected by taste. Many oxidised gummy products still taste sweet and fruity.
Which nutrients are most vulnerable to oxidation?
When we talk about “supplement oxidation,” not all ingredients carry the same risk. Some nutrients are inherently unstable—once exposed to oxygen, moisture, or heat, they degrade, lose function, or turn into harmful by-products.
💡 Special Reminder:
If these nutrients are made into gummies, they may have already partially oxidised before you even finish the bottle—especially if the product isn’t light-protected or nitrogen-sealed.
Here are the most oxidation-prone supplement ingredients:
| Category | Common Examples | What Happens When Oxidised? |
|---|---|---|
| Unsaturated Fatty Acids | Omega-3 fish oil, flaxseed oil, krill oil, DHA | Becomes cloudy, develops oily smell, produces pro-inflammatory metabolites—harmful to heart and brain |
| Antioxidant Vitamins | Vitamin C, Vitamin E, β-carotene | Loses potency, discolours, turns rancid, may trigger oxidative stress |
| Water-Soluble Vitamins | B vitamins (especially B1, B6, B12, folate) | Degrades faster in humid or warm conditions, shorter shelf life |
| Metallic Minerals | Iron, copper, zinc, selenium | May form irritating micro-molecules that harm the stomach lining or liver |
| Plant Extracts | Polyphenols, lycopene, astaxanthin, lutein | Easily denatured by heat and light, loses beneficial activity |
📱 Table can be scrolled horizontally on mobile
👶 Why Are Children’s Gummies Even Riskier?
Kids’ gummies usually have more complex formulas (multi-vitamins, minerals, flavours, colours). Since children prefer sweetness, these products tend to contain more sugar and moisture—which means:
- Higher risk of oxidation and degradation
- Harder to detect when they've gone bad
- More likely to appear “effective” while actually delivering no benefit
⚠️ Especially for iron + vitamin C gummies for kids—we generally don’t recommend them.
Once oxidised, they can generate harsh molecules that irritate the gut or overwhelm a child’s liver.
💡 Wondering how to store your supplements to prevent oxidation and nutrient loss?
We’ll cover it in detail in our next blog post.
