Energy & Metabolism Supplements

The honest answer is: it depends on why you're tired, and if you genuinely don't know, that's worth finding out before buying supplements.

Persistent, unexplained fatigue is worth discussing with your GP — common causes include iron deficiency anaemia, low vitamin D, thyroid issues and low B12, all of which can be identified through a blood test. Supplementing without knowing the cause can mean taking the wrong thing and seeing no benefit.

That said, if you're looking for a practical starting point without a GP visit, the most commonly deficient nutrients linked to low energy in the UK are:

• Iron — particularly for women of childbearing age with heavy periods
• Vitamin D — especially during autumn and winter
• Vitamin B12 — more common in those following plant-based diets or over 50
• Magnesium — commonly low in adults with high-stress lifestyles or poor sleep

A B complex covering multiple B vitamins at once is a widely used first step for general energy support, as B vitamins collectively contribute to normal energy-yielding metabolism and the reduction of tiredness and fatigue — authorised health claims in the UK. If your tiredness is stress-driven rather than nutritional, adaptogens like ashwagandha may be a more relevant addition.

You don't need both unless there is a specific reason to supplement B12 at higher doses separately.

Vitamin B12 specifically contributes to normal energy-yielding metabolism, the reduction of tiredness and fatigue, and normal psychological function. It is most commonly deficient in those following vegan or vegetarian diets (B12 is found almost exclusively in animal products) and in older adults, as B12 absorption becomes less efficient with age.

A B complex provides all eight B vitamins — B1 (thiamine), B2 (riboflavin), B3 (niacin), B5 (pantothenic acid), B6, B7 (biotin), B9 (folate) and B12 — at a combined dose. All of them contribute to normal energy-yielding metabolism; some (B6, B12, folate) also contribute to normal psychological function and the reduction of tiredness and fatigue specifically.

Practical guidance:

• If you follow a plant-based diet or are over 50 and specifically want to address B12 → a standalone B12 supplement at a meaningful dose
• If you want broad B vitamin support for everyday energy metabolism → a B complex is the more efficient approach
• If you're already taking a multivitamin that includes B vitamins → check the doses before adding a separate B complex to avoid unnecessary duplication

Ashwagandha is probably better described as a stress and resilience supplement than a traditional energy supplement — and understanding that distinction helps you decide whether it's right for you.

It is an adaptogenic herb from the Ayurvedic tradition, increasingly popular in the UK for its association with supporting the body's response to stress and promoting a sense of calm focus. It does not carry an authorised health claim for energy in the same way that B vitamins or iron do — it is positioned as a traditional herbal supplement rather than a nutrient with a defined physiological role in energy metabolism.

Where ashwagandha tends to be most useful is when tiredness is driven by stress, anxiety or poor sleep quality rather than a nutritional deficiency. If your energy dips because of a demanding lifestyle, chronic stress or difficulty winding down at night, ashwagandha may be a more appropriate addition than an iron tablet or B vitamin.

Look for products using KSM-66 or Sensoril standardised ashwagandha extract — these are the most studied forms and are the basis for the majority of available research.

Yes — and this is one of the most commonly raised concerns about iron supplementation, with practical solutions available.

Standard iron supplements (often ferrous sulphate) are effective but can cause constipation, nausea or stomach discomfort, particularly at higher doses. Several alternatives are worth considering:

• Iron bisglycinate (also called chelated iron or gentle iron) is bound to the amino acid glycine and is generally much better tolerated than ferrous sulphate at equivalent doses. It is the most widely recommended form for those with digestive sensitivity.
• Liquid iron formulas are sometimes better tolerated than capsules and allow more flexible dose adjustment if you're building up gradually
• Lower-dose supplements taken more frequently — splitting a daily dose rather than taking it all at once — can reduce digestive side effects with standard forms
• Taking iron with food reduces absorption slightly but significantly improves tolerability; most people find this a worthwhile trade-off

Iron bisglycinate is the most practical upgrade for anyone who has experienced issues with standard iron tablets.

This depends on what your multivitamin already contains — and it's worth checking before adding anything new.

Most standard multivitamins include B vitamins and often vitamin D, so adding a standalone B complex on top may result in taking duplicate doses of the same nutrients without additional benefit. At standard supplement doses this is unlikely to cause harm, but it is unnecessary spending.

Practical checklist before adding an energy supplement:

• Check what B vitamins your multivitamin provides and at what dose
• Look for iron — many multivitamins for men exclude iron or include only a small amount; many women's multivitamins include it at a more meaningful level
• Check vitamin D — if your multi includes it, you may not need a separate vitamin D supplement for energy support

Where standalone energy supplements genuinely add value alongside a standard multivitamin:

• Higher-dose B12 for those who absorb it poorly (older adults, plant-based dieters)
• Iron if your multivitamin contains little or none
• Adaptogens like ashwagandha — not typically found in multivitamins and not a duplication concern