Which Supplements Are Actually Worth Taking After 40?

For most people after 40, creatine is the one supplement with strong evidence behind it: 3 to 5 g a day when you're lifting. Everything else comes after food, sleep and training, and popular ones like vitamin D and fish oil didn't prevent heart disease, cancer or fractures in healthy adults in a big trial.

So no, the answer isn't another bottle. Here's my order, and I'm stubborn about it.

Food and lifestyle first. Then supplements. Then a naturopathic doctor.

Protein at four meals, veg on every plate, sleep and your training. That's the base. If that isn't in place, a supplement is just expensive pee.

Is creatine worth taking for women over 40?

Yes. It's the one I'll put my name on as a default.

Creatine monohydrate is the most effective nutritional supplement studied for high-intensity training capacity and lean mass, with no compelling evidence of harm in healthy people at recommended doses. At 3 to 5 g a day, your muscles fill up in about 3 to 4 weeks, so loading is optional.

And it's not a steroid. It's not "just for young men". It's a compound your body already makes. Women across the lifespan, including after menopause, are a growing area of creatine research, especially alongside strength training. Pair it with lifting (why that matters: [Does Strength Training Slow Aging?](/blog/does-strength-training-slow-aging)).

If you have kidney issues, talk to your doctor first.

Do I need vitamin D?

Maybe. But "more is better" didn't hold up.

In the VITAL trial, 25,871 adults (men 50+ and women 55+) took 2,000 IU a day for about 5 years. In generally healthy people, vitamin D didn't reduce major heart events, cancer or fractures.

So routine high doses aren't a shortcut. Whether YOU need it, and how much, depends on your blood level. Get it tested. That's your doctor's call.

What's the best magnesium?

The form matters:

• Better absorbed: citrate, aspartate, lactate and chloride, compared with oxide and sulfate.
• Most likely to send you running to the bathroom: oxide, carbonate, chloride and gluconate.
• Glycinate is a popular, gentler form, though evidence for specific forms beyond absorption is limited.

The daily target is 320 mg for women and 420 mg for men (31+). The upper limit from supplements is 350 mg a day. Magnesium from food doesn't count toward that.

For sleep: small trials in older adults with insomnia found magnesium helped people fall asleep about 17 minutes faster. Low-certainty evidence, and no clear change in total sleep. Nice, not magic.

Separate magnesium from bone medications (bisphosphonates) and some antibiotics, and check with your doctor if you have kidney disease or take reflux or water pills long term.

Should I take fish oil?

Food first. Oily fish like salmon, sardines, mackerel or trout twice a week covers it for most people.

In VITAL, 1 g a day of fish oil didn't reduce the main combined heart outcome or cancer. Heart attacks were lower in a secondary analysis, and people eating little fish may have benefited more. But treat that as a lead, not proof. High doses can interact with blood thinners.

Do I need electrolytes?

Mostly for long or hot sessions, heavy sweaters, or travel days. For a typical 45 to 60 minute lift, food and water cover it. Full breakdown in [How Much Water Should You Drink?](/blog/how-much-water-electrolytes-training). If you have high blood pressure, a heart or kidney condition, or take blood-pressure medication, check with your doctor before sodium-heavy products.

And protein powder? That's food in a tub. A shake counts as one of your four meals only if it hits 30 g of protein. Whey counts. Collagen doesn't ([here's why](/blog/does-collagen-count-as-protein)).

What supplements do I take myself?

I'll tell you, because you'll ask anyway. I take berberine, NAC, glycine, magnesium, a greens powder and a sleep formula. That's MY choice. Not a prescription, not an endorsement, not a sales pitch. Here's what the research actually says on the ones people ask about:

• Berberine. Across 37 trials in people with type 2 diabetes, it lowered fasting blood sugar by about 0.8 mmol/L and HbA1c by about 0.6%. Most trials were small, with some risk of bias. Weight results are inconsistent, and it is NOT "nature's Ozempic". Side effects are mainly stomach-related. It interacts with medications, and with diabetes medications it can push blood sugar too low. It's likely unsafe in pregnancy and breastfeeding.
• NAC. Used medically as the antidote for acetaminophen overdose and to thin mucus. Evidence for antioxidant or longevity claims is limited. Stomach upset is the most common side effect, and it can interact with nitroglycerin and add to blood-pressure lowering.
• Glycine. Small Japanese trials used 3 g before bed and reported better sleep quality and less next-day tiredness. Some researchers had links to a glycine maker. Early and limited evidence. A consistent bedtime and no late alcohol do more.
• Greens powders. Research is limited, with small trials showing higher blood levels of some nutrients and no change in overall gut diversity. Sleep formulas of this type often have no published trials as a product, and some ingredients sit below studied doses. A greens powder can fill gaps on a busy day. It does NOT replace 1 to 2 fists of veg per meal.

Natural doesn't mean safe. Berberine, NAC and magnesium all have real side effects and real medication interactions.

How do I know a supplement contains what the label says?

You don't, unless someone checked. Supplements aren't regulated like drugs, so the label may not match what's inside.

Look for third-party testing:

• NSF Certified for Sport and Informed Sport test for banned substances and contaminants.
• USP Verified checks quality and purity.

None of them proves a product WORKS. They prove it's what it says it is. That's the bare minimum.

This isn't medical advice. Never start, stop or change a medication or HRT based on anything here, and never swap a medication for a supplement. If you take diabetes, blood-pressure, blood-thinning, thyroid, psychiatric, transplant or heart medication, or you're pregnant, breastfeeding, trying to conceive, have kidney or liver disease or surgery coming up, talk to your doctor or pharmacist first.

Quick answers

What supplements should I take after 40? Start with food and lifestyle: protein at four meals, veg on every plate, sleep and training. Creatine at 3 to 5 g a day when lifting has the strongest evidence. Beyond that, a naturopathic doctor or your doctor can tailor it.

Is creatine safe for women over 40? It's one of the most researched supplements there is, and the evidence in healthy adults is reassuring. With kidney issues, check with your doctor first.

Is more vitamin D always better? No. In VITAL, routine supplementation didn't cut fractures, heart events or cancer in healthy adults. Get your level checked.

Is berberine nature's Ozempic? No. It has modest effects on blood sugar, inconsistent effects on weight, and stomach side effects. It's not a GLP-1 drug.

Does a greens powder cover my veg? No. It can't replace the fibre and volume of real veg at every meal.

Sources. Kreider RB, et al. International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation. Journal of the International Society of Sports Nutrition. 2017. Smith-Ryan AE, et al. Creatine supplementation in women's health: a lifespan perspective. Nutrients. 2021. Manson JE, et al. Vitamin D supplements and prevention of cancer and cardiovascular disease; Marine n-3 fatty acids and prevention of cardiovascular disease and cancer (VITAL). New England Journal of Medicine. 2019. LeBoff MS, et al. Supplemental vitamin D and incident fractures in midlife and older adults. New England Journal of Medicine. 2022. NIH Office of Dietary Supplements. Magnesium fact sheet. Mah J, Pitre T. Oral magnesium supplementation for insomnia in older adults. BMC Complementary Medicine and Therapies. 2021. Morton RW, et al. Protein supplementation and resistance training-induced gains in muscle mass and strength. British Journal of Sports Medicine. 2018. Xie W, et al. Glucose-lowering effect of berberine on type 2 diabetes. Frontiers in Pharmacology. 2022. NCCIH. Berberine and weight loss: what you need to know. Memorial Sloan Kettering Cancer Center. About Herbs: Berberine; N-acetylcysteine. US FDA. Policy regarding enforcement discretion for certain NAC products. 2022. Inagawa K, et al. Subjective effects of glycine ingestion before bedtime on sleep quality. Sleep and Biological Rhythms. 2006. Yamadera W, et al. Glycine ingestion improves subjective sleep quality. Sleep and Biological Rhythms. 2007. Bannai M, et al. The effects of glycine on subjective daytime performance in partially sleep-restricted healthy volunteers. Frontiers in Neurology. 2012. ConsumerLab. AG1 and AGZ reviews. Yeung S. How do I know if a dietary supplement contains what the label says? Memorial Sloan Kettering. 2014.