Supplements: Do We Really Need Them?

Walk down any pharmacy aisle and you'll find hundreds of supplements, each promising more energy, better immunity or glowing skin. So do we actually need them? The honest answer is: it depends. Ideally we'd get everything we need from food, but for many of us that isn't always possible.

In this post I'll explain what a supplement is, the seven reasons you might need one, why quality matters, and what each vitamin does, with a special look at vitamin D, the one most of us in Ireland are low in.

What Is a Supplement?

A dietary supplement is a product designed to provide nutrients that may be missing from your diet. Supplements come in many forms, including capsules, tablets, powders and liquids. The most common types are:

• Amino acids (protein)
• Fatty acids (healthy fats such as omega-3)
• Fibre
• Herbal remedies
• Minerals
• Vitamins

Seven Reasons You Might Need a Supplement

1. Soil quality

Food gets its minerals from the soil it grows in. Intensive farming can deplete soil, and studies comparing produce over several decades have found lower levels of some minerals than in the past. Some soils are naturally low in certain minerals too; selenium is a good example, as soils in Ireland and the UK tend to be low in it.

2. Modern farming and fertilisers

Many fertilisers mainly replace three nutrients: nitrogen, phosphorus and potassium (NPK). Plants need many more minerals than that, including calcium, magnesium, iron and zinc. Crops grown this way can look perfect but may contain fewer nutrients, and may be sprayed with pesticides, herbicides and fungicides along the way. Choosing organic produce where you can, and washing fruit and vegetables well, reduces your exposure to residues.

3. Stress, alcohol, smoking and the pill

Stress, regular drinking and long-term use of the contraceptive pill all increase your need for B vitamins. Smoking also reduces the absorption of several vitamins and minerals, including vitamins B6, B12, C and folate. If your diet is already low in B vitamins, these factors can tip you into a shortfall.

4. Your digestive system

What you absorb depends on how well your digestive system works, starting with chewing your food thoroughly. Symptoms such as bloating, constipation, wind or very smelly gas are your body's way of telling you something isn't right. The better your digestion, the more vitamins and minerals your body can absorb, so don't ignore the signals.

5. Diet choices

If much of your diet is fast food or processed food, it's very hard to get enough vitamins and minerals. Processed foods often provide "empty calories": energy from sugar or poor-quality fats, with few nutrients. A supplement won't make up for a poor diet, but it can help fill some gaps while you improve it.

6. Plant-based and other diets

Some ways of eating need more planning. Vegans, for example, need to think about:

• Vitamin B12, found almost only in animal foods, so a supplement is essential
• Omega-3, mainly found in oily fish; algae oil is the vegan alternative to fish oil
• Vitamin D, as most D3 supplements come from sheep's wool (lanolin); vegan D3 made from lichen is available

7. How old is your food?

The longer food sits in transport, storage and on the supermarket shelf, the more some nutrients, such as vitamin C, break down. Produce picked before it's ripe may never develop its full nutrient content. Buying local and seasonal, and using frozen vegetables, which are frozen soon after picking, can help.

Quality Matters

The form and quality of a supplement affect what your body can actually do with it.

Whole foods work as a team. Whole foods contain vitamins, minerals, fibre, protein, fats, carbohydrates, water and antioxidants that work together. When a single nutrient is isolated in a supplement, it often doesn't have the same benefits as eating it in its whole-food form. That's another reason to put food first.

Take supplements with food. Unless the label says otherwise, taking supplements with a meal usually helps absorption, especially the fat-soluble vitamins A, D, E and K, which need some fat to be absorbed. It also reduces stomach upset.

Which Supplements to Consider First

• Vitamin D3: the top supplement for most people living in Ireland. It's essential for your immune system, bones and muscles, and most of us don't get enough sunlight in autumn and winter to make our own.
• Omega-3 (fish or algae oil): helps regulate inflammation and supports your heart and brain. Worth considering if you don't eat oily fish twice a week.
• B vitamins: consider a B complex if you're under a lot of stress, drink alcohol regularly, or have been on the pill for a long time. B6, B12 and folate also help keep homocysteine at a healthy level. High homocysteine is linked with heart disease, stroke and cognitive decline, so if you have a personal or family history of these, ask your GP about a homocysteine test.

Water-Soluble and Fat-Soluble Vitamins

Water-soluble vitamins (the B vitamins and vitamin C) dissolve in water. Your body doesn't store much of them, and any excess leaves in your urine, so you need a regular supply every day.

Fat-soluble vitamins (A, D, E and K) are stored in your liver and fat tissue. They stay in your body much longer, which also means they can build up to harmful levels if you take too much.

The daily value below is the "NRV" shown on EU supplement labels. The upper limit is the most an adult can safely take every day long-term. The practitioner range is a dose often used in nutritional therapy for a specific purpose, and should only be used with professional advice.

µg = micrograms (one-thousandth of a milligram). mg = milligrams. IU = international units.

The Vitamins One by One

Vitamin C

• What it does: a powerful antioxidant that protects cells from damage; supports the immune system; helps the liver process toxins such as alcohol, smoke and pollution; needed to make collagen and some mood-related brain chemicals.
• Food sources: citrus fruit, kiwi, berries, peppers, tomatoes, broccoli (including the stems), dark leafy greens, potato skins.
• Signs you may be low: frequent infections, slow wound healing, easy bruising, bleeding gums.

Vitamin B1 (thiamine)

• What it does: helps turn carbohydrates, fats and protein into energy; needed to make acetylcholine, a brain chemical; supports healthy digestion.
• Food sources: wholegrains, brown rice, lentils, nuts, seeds, eggs, pork, brewer's yeast.
• Signs you may be low: fatigue, low mood, muscle weakness, confusion, nerve problems. Heavy drinkers are often deficient.

Vitamin B2 (riboflavin)

• What it does: helps release energy from food and activates vitamin B6. It's what turns your urine bright yellow after a B complex.
• Food sources: eggs, dairy, meat, oily fish, green vegetables, wholegrains, nuts, seeds.
• Signs you may be low: cracks at the corners of the mouth, sore lips, skin problems, tired or sensitive eyes.

Vitamin B3 (niacin)

• What it does: needed for energy production; involved in making sex hormones and serotonin, the "feel-good" brain chemical; helps manage cholesterol.
• Food sources: meat, fish, eggs, wholegrains, brown rice, nuts, seeds, avocados, mushrooms.
• Signs you may be low: fatigue, anxiety, low mood, poor sleep, skin problems.

Vitamin B5 (pantothenic acid)

• What it does: helps turn food into energy; needed to make stress hormones in the adrenal glands.
• Food sources: meat, eggs, wholegrains, brown rice, pulses, mushrooms, avocados, nuts, seeds.
• Signs you may be low: fatigue, feeling stressed or run down, low blood sugar symptoms, burning feet.

Vitamin B6 (pyridoxine)

• What it does: helps process protein and fats; needed to make neurotransmitters and hormones; helps the body use B12, magnesium and zinc.
• Food sources: poultry, fish, eggs, bananas, avocados, brown rice, wholegrains, green vegetables, nuts, seeds.
• Signs you may be low: fatigue, low mood, anxiety, PMS, skin problems, anaemia.

Vitamin B9 (folate)

• What it does: essential for making DNA and new cells, including red blood cells; helps keep homocysteine at a healthy level; vital in early pregnancy for the baby's spine and brain.
• Food sources: dark green leafy vegetables, peas, beans, lentils, chickpeas, oranges, asparagus.
• Signs you may be low: tiredness, anaemia, poor immunity, high homocysteine.

Vitamin B12 (cobalamin)

• What it does: needed for healthy nerves, red blood cells and brain function; helps keep homocysteine at a healthy level.
• Food sources: meat, fish, eggs, dairy, liver. There are no reliable plant sources.
• Signs you may be low: tiredness, memory problems, pins and needles, low mood, anaemia.
• Absorption: needs good stomach acid and a protein called intrinsic factor. It falls with age, and with medicines such as metformin and acid-reducers.

Vitamin A

• What it does: needed for vision, especially in low light; keeps skin and the linings of the gut and airways healthy; supports immunity.
• Food sources: ready-made retinol in liver, oily fish, eggs and dairy. Your body also makes vitamin A from beta-carotene in carrots, sweet potatoes, pumpkin, mango, apricots, spinach and kale.
• Signs you may be low: poor night vision, dry skin, acne, frequent infections.
• Note: avoid high-dose retinol supplements and liver in pregnancy.

Vitamin E

• What it does: an antioxidant that protects cell membranes and white blood cells; helps recycle vitamin C and glutathione, which is important for liver detoxification.
• Food sources: nuts, seeds, wheatgerm, avocados, vegetable oils, green leafy vegetables.
• Signs you may be low: rare, but can include nerve and muscle problems.

Vitamin K

• What it does: activates blood-clotting factors and helps build calcium into bone.
• Food sources: green leafy vegetables, broccoli, soya beans, fermented foods, liver.
• Signs you may be low: easy bruising, nosebleeds, weaker bones.
• Note: if you take warfarin, don't change your vitamin K intake without speaking to your GP.

Vitamin D: The One Most of Us Need

Vitamin D acts more like a hormone than a vitamin, and most of it comes from sunlight rather than food.

When UVB rays reach your skin, they turn a form of cholesterol in the skin (7-dehydrocholesterol) into vitamin D3. Your liver converts this into 25-hydroxyvitamin D, the form measured in blood tests, and your kidneys turn that into the active hormone your body uses.

In strong summer sun, exposing your arms and legs for a short time can produce far more vitamin D than the daily value. But in Ireland the sun is only strong enough between roughly April and September, and only around the middle of the day. From October to March, we make little or none.

What vitamin D does

• Keeps calcium and phosphorus at healthy levels, for strong bones, teeth and muscles
• Prevents rickets in children, and soft bones and osteoporosis in adults
• Supports a healthy immune system
• Supports normal muscle and nerve function

Researchers are also studying links between low vitamin D and low mood, heart health, autoimmune conditions and some cancers, though supplements haven't been proven to prevent these.

The sun's rays and sunscreen

• UVA rays are present all year round and pass through glass and clothing. They age the skin and don't help you make vitamin D.
• UVB rays make vitamin D, and also cause sunburn. They don't pass through glass or clothing.
• Sunscreen blocks UVB and reduces vitamin D production, though most people apply less than the tested amount. Never let your skin burn.

Food sources

Oily fish, cod liver oil, egg yolks, fortified milks and cereals, and UV-exposed mushrooms. It's very hard to get enough from food alone, which is why a supplement is usually recommended in Ireland.

Choosing and dosing a supplement

Choose vitamin D3 (cholecalciferol), which raises blood levels more effectively than vitamin D2, and take it with a meal containing some fat.

Higher doses, such as 5,000 IU or more, are sometimes used for a short time to correct a deficiency, but only after a blood test and with advice from your GP or practitioner.

Get your levels tested

Because vitamin D is stored in the body, it's worth testing your level, especially if you supplement. Irish labs usually report results in nmol/L; some private labs use ng/mL (multiply ng/mL by 2.5 to get nmol/L).

Daily Values Versus Optimal Intake

Official daily values, such as the RDA and the NRV on labels, are designed to prevent deficiency diseases like scurvy or rickets. They aren't necessarily the amounts needed for optimal health. For vitamin C, the daily value is 80 mg, enough to prevent scurvy, while many nutrition practitioners use 500 mg or more to support immunity.

That's why some practitioners work with an Optimum Daily Allowance (ODA): higher amounts, often used in research studies, aimed at long-term health rather than just avoiding deficiency.

But higher isn't automatically better. Most optimal doses are well within safe limits, but some, such as vitamin B6 above 12 mg, vitamin A, or vitamin D above 4,000 IU, can cause harm if taken long-term without supervision. If you take several supplements, add up the total of each nutrient.

Stay Safe

Check with your GP or pharmacist before starting a supplement if you:

• Take prescription medication, especially blood thinners, blood pressure tablets, diabetes medication or the contraceptive pill
• Are pregnant, breastfeeding or trying to conceive
• Have a health condition such as kidney, liver or thyroid disease
• Are having surgery soon

This article is general information, not medical advice. Always speak to your GP about persistent symptoms.