Minerals tend to get far less attention than vitamins, but for adults over 40 they are just as important and in some cases more urgently needed. Deficiencies in magnesium, zinc, and iron are genuinely common in midlife, often go undiagnosed for years, and show up as symptoms that are easy to attribute to ageing rather than nutrition.
This section covers the five minerals most worth understanding after 40. Each review goes into the research behind the mineral, the forms that actually absorb well, what dosage the evidence supports, and the interactions and safety considerations worth knowing before you start supplementing.
There are no paid placements here and no brand partnerships influencing what we recommend. The goal is simply to give you enough accurate information to make a decision that fits your situation.
Why Mineral Absorption Changes After 40
Your body’s ability to absorb minerals from food declines gradually with age, and several factors accelerate that process after 40. Stomach acid production, which plays a central role in breaking down minerals so they can be absorbed, tends to reduce as you get older. This particularly affects iron and calcium, both of which depend on an acidic stomach environment to be properly absorbed.
Hormonal changes matter too. The drop in oestrogen after menopause accelerates calcium loss from bones. Lower testosterone in men affects zinc metabolism. Chronic stress depletes magnesium faster than most people realise. And a diet that was nutritionally adequate in your 30s may not be covering your needs a decade later, especially if you’re eating less overall or have cut out food groups.
The other issue specific to minerals is that the relationship between them matters enormously. Calcium and magnesium need to be in reasonable balance. Too much zinc over time can deplete copper. High-dose iron supplementation interferes with zinc absorption. Understanding these interactions is part of what makes mineral supplementation more nuanced than simply taking more of everything.
Our Mineral Reviews
Below is every mineral we have reviewed in depth. Each is written with the specific changes and needs of adults over 40 in mind.
Magnesium
Magnesium is involved in more than 300 enzymatic processes in the body, covering everything from muscle contraction and nerve signalling to blood sugar regulation and sleep quality. It is also one of the most under-consumed minerals in Western diets, with studies suggesting a significant proportion of adults do not reach the recommended daily intake through food alone.
After 40, the consequences of low magnesium tend to become more noticeable. Poor sleep, muscle cramps, heightened anxiety, and difficulty recovering after exercise are among the most commonly reported signs. What makes this harder to detect is that standard blood tests do not reliably reflect total body magnesium, because most of it is stored in bones and tissues rather than in the bloodstream.
The form of magnesium you take matters considerably. Magnesium oxide is cheap and widely available but has poor bioavailability. Magnesium glycinate is better absorbed and gentler on the stomach, making it the preferred choice for most people. Magnesium citrate is a reasonable middle ground and also has a mild laxative effect that some find useful. Our review covers all of this in detail, along with dosage guidance and what to look for on a label. Read the full magnesium review.
Calcium
Calcium is the mineral most associated with bone health, and for good reason. Around 99% of the body’s calcium is stored in bones and teeth. After 40, and particularly after menopause for women, bone resorption begins to outpace bone formation, meaning the body is breaking down bone tissue faster than it is rebuilding it. Adequate calcium intake is one part of slowing that process.
The nuance that most general advice misses is that calcium does not work well in isolation. It needs Vitamin D for absorption in the gut, and Vitamin K2 to ensure it ends up in bones rather than in artery walls. Taking high-dose calcium supplements without these cofactors is not only less effective but potentially counterproductive for cardiovascular health.
Our review also covers the difference between calcium carbonate and calcium citrate, which matters for anyone with reduced stomach acid since carbonate requires acid to dissolve properly while citrate does not. For older adults and anyone taking acid-suppressing medication, that distinction is clinically meaningful. Read the full calcium review.
Zinc
Zinc is an essential trace mineral involved in immune function, wound healing, protein synthesis, and hormone production. For men over 40, zinc has particular relevance because it plays a direct role in testosterone metabolism and prostate health. For both men and women, it supports immune resilience and the body’s ability to repair tissue.
Zinc absorption declines with age, and deficiency is more common than most people expect, partly because the symptoms are easy to attribute to other causes. Frequent infections, slow wound healing, reduced sense of taste or smell, and fatigue are among the signs that zinc levels may be insufficient.
Not all zinc supplements are equal. Zinc picolinate and zinc bisglycinate are among the best-absorbed forms. Zinc oxide, which appears in many cheap supplements and sunscreens, has poor bioavailability and is not worth supplementing. Our review covers the forms, dosage, and the important relationship between zinc and copper that anyone supplementing long-term needs to understand. Read the full zinc review.
Iron
Iron is essential for producing haemoglobin, the protein in red blood cells that carries oxygen around the body. Deficiency results in anaemia, with fatigue, breathlessness, brain fog, and poor exercise tolerance being the most common symptoms. In adults over 40, iron deficiency is more likely in women who are still menstruating and in anyone with poor dietary intake or absorption issues.
What makes iron different from most other minerals is that supplementing without knowing your levels is genuinely inadvisable. Iron accumulates in the body, and excess iron is associated with oxidative stress and organ damage over time. Before starting iron supplements, a blood test is the right first step.
When supplementation is appropriate, the form matters for tolerability as much as effectiveness. Ferrous sulphate is commonly prescribed but causes constipation and nausea in many people. Iron bisglycinate is a gentler, well-absorbed alternative that is easier to take consistently. Our review covers when iron supplementation is and is not indicated, what to ask your GP to test, and how to take it to minimise side effects. Read the full iron review.
Selenium
Selenium is a trace mineral that supports thyroid function, antioxidant defence, and immune health. The thyroid connection is particularly relevant after 40, as thyroid issues become more common with age, especially in women. Selenium is required for the conversion of the thyroid hormone T4 into its active form T3, which means that even a mild deficiency can affect thyroid efficiency and energy levels.
Selenium is also one of the minerals where the gap between a beneficial dose and a harmful one is relatively narrow. The recommended daily intake for adults is around 55 micrograms, and the upper tolerable limit is 400 micrograms. Many multivitamins already include selenium, so adding a separate supplement on top without checking can push intake close to or beyond that upper limit.
Our review covers the best dietary sources of selenium, the difference between selenomethionine (the most bioavailable supplement form) and sodium selenite, and how to assess whether supplementation makes sense given your diet and health context. Read the full selenium review.
How to Use These Reviews
If you are unsure which minerals to prioritise, our over-40 supplement guide gives a broader overview of where to start based on the most common nutritional gaps at this life stage.
For most adults over 40, magnesium is the mineral most worth reviewing first, simply because deficiency is widespread and the symptoms overlap with so many other things. Calcium is the next most relevant, particularly for women. Zinc is worth considering if immunity, recovery, or hormonal health are concerns. Iron and selenium are both best approached after getting your levels tested rather than supplementing blind.
These reviews are also worth reading alongside our vitamins reviews, since minerals and vitamins frequently work in combination. The calcium, Vitamin D, and Vitamin K2 relationship is the most obvious example, but there are others throughout.
And as always, if you are managing a health condition or taking prescription medication, check with your GP before adding mineral supplements to your routine. Interactions between minerals and medications are well documented and worth being aware of before you start.