The Best Supplements for Women Over 40

Nutrition as the foundation: supplements as a complement

Let's establish one thing first: no supplement replaces a healthy diet. Supplements do exactly what the word says: they supplement. Your body absorbs nutrients from food far better than from pills, because food provides a complete package of fibre, co-factors and other substances that work together.

Yet there are good reasons why supplements can be worthwhile after 40. The absorption of certain nutrients decreases as you age. Many people get insufficient sunlight for vitamin D synthesis. Our agricultural soils contain fewer minerals than decades ago. And the hormonal changes of perimenopause increase the need for specific nutrients.

The art is to supplement with purpose: not everything at once, not in mega-doses, and always in consultation with your doctor if you take medication. Ideally have your blood values checked so you know where you actually have deficiencies. This prevents unnecessary supplements and under-dosing.

Below we discuss the eight supplements most relevant to women over 40, based on scientific research and the most common deficiencies at this stage of life.

1. Magnesium (bisglycinate)

What does it do?

Magnesium is involved in over 300 enzymatic processes in your body. It supports your muscles, nervous system, sleep and stress response. Magnesium helps produce the sleep hormone melatonin, lowers cortisol (your stress hormone) and relaxes your muscles. Many women in perimenopause recognise the symptoms of magnesium deficiency: muscle cramps, restless legs, insomnia, irritability and palpitations.

Why important after 40?

The need for magnesium increases during perimenopause, while absorption actually decreases. Estimates vary, but various studies suggest that 50 to 70 percent of the Western population does not get enough magnesium. Declining oestrogen levels also affect magnesium absorption in the gut, which can further widen the deficit.

Dosage and best form

The recommended dosage is 200–400 mg of elemental magnesium per day. Choose magnesium bisglycinate (also called glycinate), as it is the best absorbed and does not cause digestive problems. Magnesium citrate is a good alternative, but can accelerate bowel movements at higher doses. Avoid magnesium oxide: absorption is poor.

When to take it: In the evening, 30–60 minutes before going to sleep. The relaxing effect supports your night's rest.

2. Vitamin D3 + K2

What does it do?

Vitamin D is strictly speaking not a vitamin but a pro-hormone. It plays a central role in your calcium metabolism and bone health, immune system, mood and hormone signalling. Vitamin K2 ensures that calcium goes to your bones rather than your blood vessels. That is why D3 and K2 are preferably combined.

Why important after 40?

After 40, bone density decreases — a process that accelerates during perimenopause due to declining oestrogen levels. Vitamin D is essential for absorbing calcium and keeping your bones strong. In many countries, sunlight from October to March is insufficient to produce vitamin D in your skin. Research shows that a large proportion of adults have too low a vitamin D level, especially in winter.

Moreover, a low vitamin D level is associated with a greater chance of depressive complaints, fatigue and a weakened immune system — complaints that many women in menopause recognise.

Dosage and best form

Many health authorities advise 10 mcg (400 IU) per day for adults, but many orthomolecular doctors and recent studies suggest that 25–50 mcg (1,000–2,000 IU) per day is needed for an optimal blood level (75–125 nmol/L). Have your blood level checked and adjust the dosage accordingly. Choose vitamin D3 (cholecalciferol), combined with vitamin K2-MK7 (at least 75–100 mcg).

When to take it: At breakfast or lunch, with a meal that contains fat (vitamin D is fat-soluble).

3. Omega-3 fatty acids

What do they do?

Omega-3 fatty acids, particularly EPA and DHA, have a powerful anti-inflammatory effect. They support brain function, the cardiovascular system and play a role in hormone production. EPA is especially helpful for anti-inflammatory processes, while DHA is important for the brain and nervous system.

Why important after 40?

Chronic low-grade inflammation is one of the biggest disruptors of hormone balance and increases with age. Omega-3 helps reduce this inflammation. Research shows that omega-3 can reduce hot flushes, improve mood and support insulin sensitivity. It also protects your heart, as cardiovascular disease is the number one cause of death in women after menopause.

Most people eat insufficient oily fish (two to three portions per week is the recommendation). If you don't reach that, a supplement is a sensible addition.

Dosage and best form

Aim for at least 1,000–2,000 mg EPA + DHA combined per day. Note: this is not the same as the total amount of fish oil on the label. Always check the EPA and DHA content separately. Choose a supplement in triglyceride form (better absorbed than ethyl ester). Algae oil is a good plant-based alternative.

When to take it: With a meal containing fat, to improve absorption and prevent fishy burps.

4. Vitamin B complex

What does it do?

The B vitamins work as a team. Vitamin B6 is involved in the production of progesterone and serotonin. B12 supports your energy metabolism and nervous system. Folate (B9) is important for cell division and methylation processes — a biochemical process crucial for the breakdown of hormones. Biotin (B7), niacin (B3) and the other B vitamins round out the picture.

Why important after 40?

The absorption of B vitamins, particularly B12, decreases as you age because stomach acid production declines. Medications such as acid suppressants and the contraceptive pill further lower B vitamin levels. A deficiency in B vitamins manifests as fatigue, concentration problems, tingling, mood swings and elevated homocysteine levels (a risk factor for cardiovascular disease).

Dosage and best form

Choose a B complex with all eight B vitamins in their active (methylated) forms: methylcobalamin (B12) instead of cyanocobalamin, and methylfolate (B9) instead of folic acid. This is especially important for women with an MTHFR gene variant (estimated 30–40% of the population), who convert folic acid less efficiently.

When to take it: In the morning at breakfast. B vitamins support energy production and can disturb sleep if taken in the evening.

5. Iron: only when deficient

What does it do?

Iron is essential for oxygen transport in your blood and plays a role in energy production. Iron deficiency (the most common nutritional deficiency worldwide) leads to anaemia, extreme fatigue, dizziness, hair loss and concentration problems.

Why important after 40?

During perimenopause, periods can become heavier and more irregular, causing greater iron loss. At the same time, many women consume insufficient iron through their diet, especially if they eat little red meat. But note: after menopause (when periods stop), you actually need less iron. Too much iron is harmful and can cause oxidative stress.

Dosage and best form

Only supplement iron based on blood tests. Have your ferritin (iron stores) measured. An optimal level is between 50–100 mcg/L. If supplementation is needed, choose iron bisglycinate (14–28 mg per day). This form is well absorbed and causes fewer gastrointestinal side effects than iron fumarate or sulphate.

When to take it: On an empty stomach, preferably with vitamin C (a glass of orange juice or a kiwi) to improve absorption. Do not take iron at the same time as coffee, tea, dairy or calcium, as these inhibit absorption.

6. Zinc and Selenium

What do they do?

Zinc and selenium are two trace elements that play a key role in your thyroid function and immune system. Your thyroid regulates your metabolism, energy level and body temperature — functions that falter in many women over 40. Zinc is also involved in the production of sex hormones and the regulation of oestrogen. Selenium protects the thyroid against oxidative damage and is needed for the conversion of the inactive thyroid hormone T4 to the active T3.

Why important after 40?

Thyroid problems occur remarkably often in women in perimenopause and menopause. The symptoms (such as fatigue, weight gain, feeling cold and hair loss) overlap strongly with menopausal complaints, which means they are often overlooked. Sufficient zinc and selenium support optimal thyroid function. Moreover, many soils are poor in selenium, meaning our food contains relatively little.

Dosage and best form

Zinc: 15–25 mg per day as zinc bisglycinate or zinc picolinate. Do not take zinc in high doses for extended periods, as this can cause a copper deficiency. A supplement with zinc and copper in a 10:1 ratio is ideal.

Selenium: 100–200 mcg per day as selenomethionine. Two to three Brazil nuts per day already provide sufficient selenium — a natural and inexpensive option.

When to take it: With a meal, to prevent stomach complaints. Do not take zinc at the same time as iron, as they compete for absorption.

7. Ashwagandha

What does it do?

Ashwagandha (Withania somnifera) is an adaptogenic herb that has been used for centuries in Ayurvedic medicine. Adaptogens help your body adapt to stress by regulating the cortisol response. Ashwagandha is the most researched adaptogen and consistently shows positive effects in clinical studies on stress reduction, sleep quality and anxiety.

Why important after 40?

Chronically elevated cortisol — something many women in perimenopause experience — disrupts your entire hormone system. It inhibits the production of progesterone, raises blood sugar, promotes fat storage around the belly and disturbs sleep. Ashwagandha helps normalise cortisol levels. Several studies show that it can lower cortisol by 20–30% after eight weeks of use.

In addition, ashwagandha supports thyroid function and can improve sleep quality — two common pain points for women over 40.

Dosage and best form

The most researched dosage is 300–600 mg KSM-66 or Sensoril extract per day. These are standardised extracts with a guaranteed content of withanolides (the active compounds). Start with 300 mg and build up if needed. Use ashwagandha in cycles of eight to twelve weeks, with a break in between.

When to take it: In the evening with food for a calming effect and better sleep. At higher doses you can split the intake between morning and evening.

Note: ashwagandha is not suitable if you take thyroid medication, are pregnant or have autoimmune conditions. Always consult your doctor.

8. Probiotics

What do they do?

Probiotics are live micro-organisms that support your gut flora. A healthy gut is essential for the absorption of nutrients, the breakdown of hormones (via the estrobolome) and the production of serotonin, the happiness hormone of which around 90% is produced in your gut. A disturbed gut flora can lead to an accumulation of oestrogen, inflammatory reactions and mood problems.

Why important after 40?

With age, the diversity of your gut flora decreases. Stress, medication use (antibiotics, acid suppressants), insufficient fibre and excessive sugar and alcohol consumption accelerate this process. During perimenopause, the gut plays an extra important role: the estrobolome — a group of gut bacteria that recycles oestrogen — can become unbalanced, which may worsen complaints.

Dosage and best form

Choose a probiotic with at least 10 billion CFU (colony forming units) and multiple strains, including Lactobacillus and Bifidobacterium. Quality matters more than quantity here: choose a supplement with scientifically researched strains and guaranteed shelf life. Keep probiotics refrigerated, unless the label states otherwise.

When to take it: On an empty stomach, in the morning 15–30 minutes before breakfast, or just before going to sleep. Combine with prebiotics (fibre) from your food: onion, garlic, leek, banana, oats and asparagus feed the good bacteria.

A good alternative to a supplement is eating fermented food daily: sauerkraut (unpasteurised), kefir, kimchi, kombucha or miso. This provides both probiotics and other bioactive substances.

What you do NOT need

The supplement industry is a multi-billion market, and not everything sold is worthwhile. In fact, some popular supplements can do more harm than good. Here is an honest overview:

Overdosing on fat-soluble vitamins

Vitamins A, D, E and K are stored in your body. Mega-doses — popular in some supplement stacks — can be toxic. More is not better. Stick to the recommended dosages and have your blood values checked if in doubt.

Expensive ‘superfood’ powders

Acai, spirulina, chlorella and moringa are presented as miracle remedies, but the scientific evidence is often thin. They are not harmful, but the promises are disproportionate to the evidence. Your money is better spent on quality basic nutrition and the supplements we discussed above.

Mega-doses of vitamin C

Your body can absorb a maximum of 200–500 mg of vitamin C at a time. Everything above that is excreted via your urine. If you eat a varied diet with sufficient vegetables and fruit, you already get enough vitamin C through your food.

Collagen supplements

Collagen is a protein that is broken down in your stomach into amino acids, just like any other protein. The claim that ingested collagen directly restores your skin or joints is not scientifically convincing. Better to invest in sufficient protein from your diet and vitamin C (needed for collagen synthesis in your body).

Influencer supplement stacks

Be critical of expensive supplement combinations promoted online. Many influencers have no medical background and earn commission on sales. A good basic stack of magnesium, vitamin D3+K2 and omega-3 costs no fortune and covers the most important deficiencies for most women.

Summary and action plan

After reading this article you hopefully have a clear picture of which supplements are worthwhile and which are not. Here is your action plan in five steps:

Step 1: Get your foundation in order

Focus first on varied, unprocessed food with sufficient protein, healthy fats, vegetables and fibre. Read our article on nutrition and hormone balance for concrete tips.

Step 2: Have your blood tested

Ask your doctor to check vitamin D, B12, ferritin (iron), thyroid function and possibly magnesium. This gives you a factual basis for supplementing.

Step 3: Start with the basic three

For most women over 40, this forms a solid foundation:

• Magnesium bisglycinate: 300–400 mg in the evening
• Vitamin D3 + K2: 1,000–2,000 IU with a meal containing fat
• Omega-3 (EPA + DHA): 1,000–2,000 mg with a meal

Step 4: Supplement based on your personal situation

• A lot of stress or sleep problems? Consider ashwagandha.
• Heavy periods? Have your iron checked.
• Low energy? Check your B12 and consider a B complex.
• Gut complaints? Start with probiotics or daily fermented food.
• Thyroid complaints? Ensure sufficient zinc and selenium.

Step 5: Evaluate after three months

Supplements are not a quick fix. Give your body at least eight to twelve weeks to respond. Track how you feel: sleep, energy, mood, skin, digestion. Have your blood checked again after three months to see whether your values are improving.

Supplements can be a valuable tool in perimenopause, but only as part of a broader picture. Good nutrition, regular exercise, stress management and sufficient sleep together form the foundation. Supplements are the finishing touch that helps you fill the last gaps.

Would you like personal supplement advice tailored to your situation? At FEM Rebalance we look at the complete picture: nutrition, exercise, sleep and supplements. Everything tailored to your body and your stage of life.