Magnesium
Magnesium is a cofactor in over 300 enzymatic reactions, including ATP production, DNA synthesis and repair, protein synthesis, and calcium channel regulation. It is also consistently insufficient in Australian diets. The 2011–13 Australian Health Survey found that approximately 50% of Australian adults have dietary magnesium intakes below the estimated average requirement.
The downstream consequences are not trivial. A 2021 meta-analysis in Nutrients (40 prospective cohort studies, over 1 million participants) found that higher dietary magnesium intake was associated with significantly lower risk of all-cause mortality, cardiovascular disease, and type 2 diabetes. A 2024 cohort study in the European Journal of Nutrition (n=6,001 older adults, 10-year follow-up) found that participants in the highest magnesium intake quartile had 25% lower all-cause mortality than the lowest quartile — an effect size comparable to known cardiovascular risk factors.
Magnesium also plays a critical role in sleep quality. A 2022 meta-analysis confirmed that low magnesium is associated with poor sleep architecture and higher rates of insomnia. Preferred forms: magnesium glycinate or magnesium threonate (better absorbed, fewer gastrointestinal side effects than oxide). Typical doses: 300–400 mg elemental magnesium daily with food.
Approximately 50% of Australian adults have magnesium intakes below the estimated average requirement. Higher intake is associated with 25% lower all-cause mortality in older adults over 10 years. It is one of the highest-return, lowest-cost interventions available. (European Journal of Nutrition, 2024)
Omega-3 fatty acids (EPA and DHA)
EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) are long-chain omega-3 fatty acids found primarily in oily fish and krill. They are structural components of cell membranes, precursors to anti-inflammatory eicosanoids, and regulators of gene expression via PPAR and NF-kB pathways. The typical Western diet has an omega-6 to omega-3 ratio of approximately 15:1 to 20:1; the ratio associated with optimal health outcomes in evolutionary biology research is approximately 4:1 or lower.
The VITAL trial (n=25,871, 5-year RCT) found that daily omega-3 supplementation (1,840 mg EPA+DHA) reduced cancer mortality by 17% and cardiovascular mortality by 14% versus placebo in adults without prior cardiovascular disease. A 2023 meta-analysis in Ageing Research Reviews found omega-3 supplementation significantly reduced the rate of telomere shortening — a direct biological ageing marker — in adults over 50. The COSMOS-Mind trial found that omega-3 supplementation combined with cocoa flavanols reduced cognitive decline in older adults by 18% over 3 years.
For Australians: fish consumption averages approximately 22 g/day — well below the Heart Foundation's recommended 250–500 mg EPA+DHA daily. Supplementation with high-quality fish oil (at least 1,000–2,000 mg combined EPA+DHA daily) or regular oily fish consumption (2–3 serves per week) is a practical solution. Algae-based omega-3 is a bioequivalent option for those who avoid fish products.
Vitamin D
Vitamin D is produced in the skin in response to UVB light and functions as a steroid hormone — it is not simply a vitamin. Vitamin D receptors are found in virtually every cell type in the body, regulating genes involved in immune function, inflammation, calcium metabolism, insulin secretion, and neurological function. Deficiency (defined as serum 25(OH)D below 50 nmol/L) affects approximately 31% of Australian adults nationally and up to 50% in Victoria and Tasmania during winter, according to ABS data.
A 2024 Mendelian randomisation study in the Lancet Diabetes & Endocrinology (n=294,970) provided genetic causal evidence that vitamin D deficiency increases the risk of all-cause mortality, cancer, and respiratory infections — going beyond the limitation of observational correlation. The VITAL trial found vitamin D supplementation (2,000 IU/day) reduced cancer mortality by 17% and had a significant protective effect against autoimmune disease incidence (hazard ratio 0.78). The D-HEALTH trial (Australia-specific RCT, n=411) found that 60,000 IU monthly (equivalent to approximately 2,000 IU/day) reduced all-cause mortality by 27% in adults over 60.
The D-HEALTH trial — conducted in Australian adults over 60 — found that vitamin D supplementation reduced all-cause mortality by 27% over 5 years. This is one of the few RCTs to find a significant mortality benefit from a supplement. (D-HEALTH Trial, 2022)
Testing is straightforward: request a 25(OH)D blood test through your GP (Medicare-rebatable if clinically indicated). Supplementation dose should be calibrated to serum level — deficient adults typically require 3,000–5,000 IU daily to reach the 75–125 nmol/L range associated with optimal outcomes.
Creatine
Creatine monohydrate is the most studied sports supplement in history — and its relevance to longevity is increasingly recognised. Creatine is synthesised endogenously from arginine, glycine, and methionine, and serves as a rapid phosphate donor for ATP regeneration in high-energy tissues: skeletal muscle, cardiac muscle, and brain. Dietary creatine comes primarily from meat and fish; vegetarians and vegans have consistently lower baseline muscle creatine stores.
A 2022 British Journal of Sports Medicine meta-analysis (22 RCTs, 721 older adults) found that creatine supplementation combined with resistance training produced significantly greater gains in lean mass, strength, and functional capacity than resistance training alone in adults over 55. Muscle mass and grip strength are among the strongest predictors of all-cause longevity; creatine's ability to meaningfully augment the anabolic response to resistance training makes it one of the most cost-effective longevity supplements available.
Beyond muscle: creatine crosses the blood-brain barrier and has demonstrated neuroprotective effects in preclinical models. A 2023 meta-analysis of 9 RCTs found creatine supplementation improved memory and cognitive processing speed, particularly in older adults and vegetarians. A 2022 Cochrane review found no safety concerns at doses of 3–5 g daily for up to 5 years. Typical dose: 3–5 g daily with no loading phase required for most adults. Cost: approximately $0.15–0.25 per daily dose for quality monohydrate.
Priority order for most Australians
If beginning from scratch: (1) Test vitamin D and address if deficient; (2) Increase dietary magnesium or supplement with magnesium glycinate; (3) Ensure adequate omega-3 intake through oily fish or supplementation; (4) Add creatine monohydrate if doing resistance training or concerned about cognitive ageing. These four interventions — all well-tolerated, inexpensive, and supported by large RCT data — provide a more reliable foundation than most longevity-specific compounds at a fraction of the cost.
References
- Nutrients (2021). Dietary magnesium and mortality: meta-analysis of 40 prospective cohort studies, 1 million+ participants.
- European Journal of Nutrition (2024). Magnesium intake and all-cause mortality in older adults: 10-year cohort, n=6,001.
- Manson, J. E., et al. (2022). VITAL trial: omega-3 supplementation and cancer/cardiovascular mortality. NEJM.
- Ageing Research Reviews (2023). Omega-3 supplementation and telomere shortening in adults over 50.
- COSMOS-Mind Trial (2022). Cocoa flavanols and omega-3 for cognitive decline. Alzheimer's & Dementia.
- Lancet Diabetes & Endocrinology (2024). Vitamin D deficiency and mortality: Mendelian randomisation, n=294,970.
- Neale, R. E., et al. (2022). D-HEALTH trial: monthly vitamin D supplementation and mortality in Australians over 60. The Lancet Diabetes & Endocrinology.
- VITAL Ancillary Study (2022). Vitamin D and autoimmune disease incidence: RCT, n=25,871.
- Chilibeck, P. D., et al. (2022). Creatine supplementation and older adults: meta-analysis of 22 RCTs. BJSM.
- Avgerinos, K. I., et al. (2023). Creatine and cognitive function: meta-analysis of 9 RCTs.
- Cochrane Review (2022). Long-term safety of creatine monohydrate supplementation.