Supplement expiry dates are legally required but their clinical significance varies enormously. Unlike some medications where expiry indicates genuine safety concerns, most supplement expiry dates indicate a potency guarantee rather than a safety threshold — the manufacturer guarantees the label dose up to that date, not that the product becomes dangerous after it. Here is the nuanced guide to what actually changes after expiry.
What Does “Best Before” or “Use By” Mean on a Supplement?
UK supplement regulations require an expiry or best-before date. This date represents the point up to which the manufacturer guarantees the stated potency — that each tablet or capsule contains the dose on the label. After this date:
- The product does not automatically become unsafe
- The potency may have declined from the stated dose
- The rate of decline depends entirely on the supplement type, storage conditions and packaging
Supplements That Lose Potency Significantly After Expiry
Probiotics — the most affected category
Live bacteria are inherently unstable. Probiotic CFU counts decline continuously after manufacture and the expiry date represents the point at which the manufacturer guarantees the stated CFU count. After expiry, CFU counts can drop significantly — meaning you may be getting substantially fewer live bacteria than the label states. Probiotic expiry dates matter more than any other supplement category. Refrigerated storage slows decline; room temperature storage accelerates it.
Omega-3 fish oil — rancidity risk
Omega-3 fatty acids oxidise — they go rancid. Rancid fish oil produces higher levels of aldehydes and peroxides that may have pro-inflammatory rather than anti-inflammatory effects. Signs of rancidity: a strong fishy smell (fresh fish oil should smell only mildly oceanic) or a bitter taste. Refrigerating fish oil significantly extends quality. After expiry, check smell and taste rather than discarding automatically.
Vitamin C — oxidises relatively quickly
Ascorbic acid is susceptible to oxidation — it turns from white to yellow/brown as it oxidises to dehydroascorbic acid. While the oxidised form retains some biological activity, potency is reduced. Visible yellowing is a sign of significant degradation. Vitamin C in airtight, dark, cool conditions lasts well; in warm, humid or light-exposed conditions degrades faster.
Supplements That Retain Potency Well Beyond Expiry
Minerals — highly stable
Mineral salts (magnesium glycinate, zinc citrate, calcium carbonate, iron bisglycinate) are chemically very stable — they do not oxidise or biodegrade. Mineral tablets and capsules stored in cool, dry conditions retain their potency for years beyond their stated expiry. The expiry date on a mineral supplement is largely a regulatory formality.
Fat-soluble vitamins in stable forms
Vitamins A, D, E and K in stabilised forms (retinyl palmitate, cholecalciferol, tocopheryl acetate, phylloquinone) are reasonably stable when protected from light, heat and moisture. Potency decline after expiry is gradual rather than dramatic in proper storage conditions.
B vitamins in tablets
B vitamins in solid tablet form are moderately stable. Some (like thiamine B1) are more susceptible to heat and moisture than others. Properly stored, B vitamin tablets retain reasonable potency for 1–2 years beyond expiry. B vitamins in liquid form are less stable.
Storage That Extends Supplement Life
- Cool and dry — most supplement degradation is accelerated by heat and humidity. Store in a cupboard away from the cooker and bathroom. Not in the fridge (unless specified) as temperature cycling from opening and closing creates condensation.
- Away from light — UV light degrades vitamin C, omega-3 and some B vitamins. Dark glass or opaque bottles provide protection; clear plastic does not.
- Airtight caps — oxygen exposure accelerates oxidation of vitamin C, omega-3 and fat-soluble vitamins. Replace caps tightly after use.
- Probiotics — refrigerate unless the product is specifically formulated for shelf stability (some are now encapsulated to be shelf-stable at room temperature without significant CFU decline).
Practical Guidance — When to Discard
| Supplement type | Expiry date importance | When to discard |
|---|---|---|
| Probiotics | High | At or just after expiry; always refrigerate |
| Omega-3 / fish oil | Moderate — check quality | When it smells strongly fishy/rancid |
| Vitamin C tablets | Moderate | When visibly yellowed or 1–2 years post-expiry |
| Mineral supplements | Low | Only if damaged, wet or visibly degraded |
| Multivitamins | Moderate — probiotic/vit C components | 1 year post-expiry if stored well |
| Fat-soluble vitamins (A, D, E, K) | Low-moderate | 1–2 years post-expiry if stored in dark, cool, dry conditions |
| Collagen powder | Low — protein is stable | Only if clumped, discoloured or smells off |
All BioBodyBoost products have manufacturing dates and expiry dates on every pack. Probiotic products (BioTic 20 Billion, SaccharoMyTum) should be used within their expiry dates and stored as directed. Browse the full range.
