Best Supplements for You The benefits and potential side effects

October 3, 2025

Explore the good and bad of supplements.

As we get older, so we take more pills whether it’s dealing with high cholesterol or blood pressure  or for other benefits. The latest figures from Mintel, the market research agency, show that 70 per cent of adults in the UK report having taken a vitamin, mineral or other supplement, fuelling a market worth over £600 million annually. The figures show that it is middle-aged and older people concerned about ageing and its implications who are driving the trend for daily intake of the products.

But what should you take, if anything? If in doubt, speak to a GP or pharmacist before taking a pill or powder, especially if you are on other medication or have underlying health conditions.

Here is a guide to supplements and what you should know.

Vitamin D

Supplement: 800–1,000 IU/day (check doctor if you need more)

• Why it’s important:
  • Boosts calcium absorption → protects bones, lowers fracture risk.
  • Supports muscle function → reduces risk of falls.
  • Strengthens immune system → may lower infection risk.
  • Low vitamin D is linked to fatigue, muscle weakness, and mood changes.

• Food Sources: Oily fish (salmon, sardines), fortified milk, eggs

• Risk: High doses can cause nausea, kidney damage, or high calcium (hypercalcemia → confusion, heart rhythm problems).

Calcium

1,200 mg/day (diet + supplements)

• Why it’s important:
  • Essential for bone density → lowers risk of osteoporosis and fractures.
  • Helps with muscle contraction and nerve function.
  • Supports heart rhythm.
  • After 65, bone breakdown often outpaces bone building, so calcium intake is critical.

• Food Sources: 1 cup milk/yogurt ≈ 300 mg, 1 oz cheese ≈ 200 mg, Leafy greens, almonds, fortified plant milks

• Risk: Too much can cause constipation, kidney stones, or increase heart disease risk if not balanced with vitamin K2 and magnesium.

Vitamin B12

500–1,000 mcg weekly (or daily if advised)

• Why it’s important:
  • Maintains healthy nerves → protects against numbness, tingling, and balance problems.
  • Supports memory and cognitive function → low B12 is linked to confusion, depression, even dementia-like symptoms.
  • Prevents anaemia (helps red blood cell formation).
  • Absorption declines with age (less stomach acid, some meds like metformin or PPIs block absorption).

• Food Sources: Meat, fish, eggs, fortified cereals

• Generally safe, even at high doses, because excess is excreted in urine.

• Food Sources: Meat, fish, eggs, fortified cereals

• Caution: Rarely may cause acne-like skin rash or interact with very high potassium supplements.

Omega-3 Fatty Acids (EPA & DHA)

250–500 mg/day (fish oil or algae oil)

• Why it’s important:
  • Heart health → helps reduce blood pressure, triglycerides, and inflammation.
  • Brain health → may support memory, slow cognitive decline.
  • Eye health → lowers risk of age-related macular degeneration (AMD).
  • Joint health → can ease stiffness in osteoarthritis.

• Food Sources: 2 portions oily fish weekly (salmon, sardines, trout)

• Risk: High doses (>3 g/day) may thin blood, raising bleeding risk (especially if on aspirin, warfarin, or other anticoagulants).

• Side effects: Fishy aftertaste, nausea, diarrhoea.

Magnesium

200–400 mg/day if intake is low or deficiency confirmed

• Why it’s important:
  • Supports nerve & muscle function → reduces cramps, spasms.
  • Helps regulate heartbeat.
  • Plays a role in blood sugar control and energy production.
  • Low magnesium may worsen insomnia, anxiety, or fatigue.

• Food Sources: Nuts, seeds, beans, spinach, whole grains

• Risk: High doses (esp. from supplements, not food) → diarrhoea, low blood pressure, irregular heartbeat.

• Interaction: Can reduce absorption of some antibiotics and osteoporosis drugs (bisphosphonates).

Protein (via food or supplements)

~1–1.2 g per kg body weight daily

• Why it’s important:
  • Prevents muscle loss (sarcopenia), which increases risk of falls.
  • Supports wound healing and recovery from illness/surgery.
  • Helps maintain energy and metabolic health.
  • Many older adults eat less protein due to appetite changes, chewing difficulty, or cost.

• Food Sources: Nuts, seeds, beans, spinach, whole grains

• Risk: Some powders are high in sugar or additives.

• Caution: People with kidney disease must limit protein.

Probiotics (optional)

• Why it’s important:
  • Supports gut microbiome → better digestion, less constipation.
  • May reduce antibiotic-associated diarrhoea.
  • Possible immune system benefits.

• Generally safe but may cause bloating or gas at first.

• Caution: In severely immunocompromised people, very rare bloodstream infections reported.

Other Condition-Specific Supplements (only if needed)

• Iron → Treats anaemia and fatigue (only if deficiency confirmed).
  • Risk: Can cause constipation, stomach upset, and in excess → organ damage.
  • Interaction: Interferes with thyroid meds, some antibiotics, and calcium.

• Folate → Supports red blood cell production and cognition.

• Vitamin K2 → Works with vitamin D & calcium to strengthen bones and prevent calcium build up in arteries.

• Risk: High doses can mask vitamin B12 deficiency (dangerous, as nerve damage may continue unnoticed).

Safe Supplement Guide for Seniors (65+)

Key Safety Notes

• Ranges are general — personal needs may differ.
• Supplements should fill gaps in diet, not replace balanced meals.
• Always check blood tests (vitamin D, B12, iron, folate) before high-dose supplementation.
• Bring a full list of supplements + medications to every doctor visit.

While these supplements have real benefits, “more” isn’t always better.

You may be interested in Improving your Nutrition or the Benefits of a Simple Diet