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A review of the evidence for the benefits of supplementation on overall health

Natural medicines have grown in popularity in recent years and have been shown in many cases to be very effective in treating and preventing many medical conditions. However, in recent years an increasing number of studies have questioned claims that taking health supplements brings major health benefits. For example, a study
in the journal Heart in 2012 concluded that those taking calcium supplements to strengthen bones may have double the risk of heart attack.


A Harvard study, published in November 2012, concluded that multivitamins have no benefit on cardiovascular health. According to some health experts, individuals who believe they are deriving benefits from supplements may be less likely to engage in other preventive health behaviours, such as eating their traditional five-a-day and exercising regularly. According to the British Diabetic Association, if you have a balanced diet such as five portions of fruit and veg a day, eating oily fish regularly, and food from all groups and you are well, then you should not need to take supplements.

However, according to the British Diabetic Association, there were some groups of people — such as the underfives, pregnant and breastfeeding women, and the elderly — who can benefit from supplements, as recommended by Department of Health. University College London researchers, using a health survey of 65,226 men and women in England from 2001 to 2008, indicated the more fruit and vegetables people ate, the less likely they were to die at any given age and went on to advocate ‘seven-a-day’ in relation to fruit and vegetables.

However, leading experts, including from Public Health England, responded to the seven-a-day recommendation by saying that while seven-a-day is aspirational in most cases, the fact is that many struggled to get to the recommended five-a-day. Five-aday should still be what health authorities should be advising people to aim for, and anything more is a bonus, they said. The purpose of this article is to give a brief overview of the main vitamins, minerals and supplements available, as well as contraindications and drug interactions to look out for.


There are many benefits but also many risks with natural remedies and herbal supplements. The common theme with most of the health benefits and risks of natural medicines is that the benefits are at best supported by a few smaller, inconclusive, and poorly-structured studies or at worst, by anecdotal evidence only.

The main issue is that the majority of natural or herbal medicines have and never will undergo detailed and well-organised clinical studies; this is because the active ingredients are not patented and widely available, meaning pharmaceutical companies will not spend the billions of euro needed to gather evidence from clinical trials needed to give conclusive evidential analysis; simply put, there will be no return on investment as they will not have exclusive rights to the ingredient. While there are some benefits, we will never fully know the full benefits of most supplements.


There can be a general perception that just because a medicine is natural that it must be safe. However, like any medicine, there are possible side-effects and situations where they should not be used. People should be
aware of these. People should always check with their pharmacist before taking a natural medicine, especially if suffering from a long-term medical condition or while taking a prescription medicine.


EU rules came into law from May 2011 regarding the sale of herbal medicines and supplements. The rules protect consumers from potential adverse effects of herbal medicines and supplements. These rules mean herbal medicines and supplements must be manufactured to the same standards as conventional medicines and must be proven safe before they can be sold.

The Health Products Regulatory Authority (HPRA) has been registering herbal medicines in Ireland since 2007, and as of 2011, any herbal medicine or supplement not registered with the HPRA by the manufacturer can no longer be sold. Importantly, these rules now mean that supplement manufacturers can no longer make unsubstantiated or unproven health claims about their products; this was an important step in protecting the public from unnecessary or unsafe use of supplements.

The HPRA actively monitors the claims made by supplement manufacturers and has made manufacturers pull products off the market where unfounded health claims were being made. You can view herbal and natural medicines registered on the HPRA website:


Echinacea is used to fight-off infections including bacteria, viruses, and fungus. It is most commonly used to prevent and fight-off colds and flus. There have been a few small studies showing its effectiveness; however,
there are no well-designed or conclusive clinical trials to prove the effectiveness of echinacea. Side-effects are extremely rare with echinacea, though allergic reactions, while very uncommon, have occurred in the past. There
is little evidence of echinacea interacting with other medicines, but it is best avoided with warfarin, as there is anecdotal evidence it increases its effect. It should not be used by people with multiple sclerosis and AIDS.


Garlic is an antioxidant and may help at preventing and fighting colds. It is thought to stimulate the activity of white blood cells, which means it helps fight-off infection. It is also known to stimulate enzymes in the liver
that get rid of toxic substances in the body, including carcinogens. Garlic is thought to be beneficial in preventing heart disease. There is some evidence that it helps reduce blood pressure. Garlic interacts with warfarin to increase the risk of bleeding and it reduces the blood concentration of some HIV drugs, such as saquinavir, so should not be used with these medicines.


Ginseng is commonly used to boost energy and stamina. There are some who believe it boosts concentration and memory. It is thought to do this by boosting the activity of neurotransmitters in the brain. It may also increase the body’s resistance to stress. There is anecdotal evidence that it acts as an aphrodisiac, however there is no clinical evidence of this. The incidence of side-effects is low, however there are some reports of temporary nervousness, headache, insomnia, inability to concentrate, increase in blood pressure and allergies.

There are some reports of an oestrogen-like effect in postmenopausal women causing vaginal bleeding in some elderly patients. It should not be used in pregnancy, people with high blood pressure and diabetics. It should be avoided by those suffering from inflammatory conditions and COPD, as there is evidence it makes them worse. It interacts with steroidal drugs used for inflammatory conditions like bronchitis and arthritis and it increases the effect of some diabetic drugs.

Echinacea is used to fight-off infections including bacteria, viruses, and fungus

St John’s Wort

St John’s Wort is well known for its mild antidepressant properties. It is thought to be effective for mild-to-moderate depression. Its active ingredient is hypercin, which is thought to influence the level of serotonin,
dopamine, and noradrenaline in the brain to boost mood. It is thought to work in a similar way to SSRIs. In some countries such as Germany, it is commonly used to treat mild depression, especially in children and adolescents. Several trials have been done on St John’s Wort, but according to the National Medicines Information Centre in St James’s Hospital, Dublin, “most have been flawed due to the methodology, selection criteria or rating scales used”. A report in a Cochrane Review in 2008 stated that it is as effective as standard antidepressants and with fewer side-effects.

Other studies have been less conclusive. St John’s Wort is available over the counter in many countries but has been a prescription-only medicine in Ireland and the UK since 2000 because of serious concerns about its safety. The main problem is that it interacts with so many medicines. This is because it stimulates an enzyme called cytochrome P450 in the body, which is a major enzyme in breaking down and getting rid of drugs from our bodies. Therefore, it reduces the effect of many drugs.

This is especially true for drugs with ‘narrow therapeutic indexes’, meaning there is a fine balance between them being non-effective, effective, and toxic. Therefore, it should not be used by people taking warfarin for blood clots, digoxin for heart conditions, cyclosporin for organ transplants and theophylline for asthma and bronchitis. Other major interactions are with benzodiazepines and HIV medication. It can also reduce the effect of oral contraceptives, leading to unplanned pregnancies.

It should not be taken with prescription antidepressants. Side-effects reported with St John’s Wort include gastrointestinal side-effects, dizziness, confusion, drowsiness, and increased sensitivity to light. NICE, the drug advisory body in the UK, advises against taking St John’s Wort because of variations in strengths of different
preparations, concerns about appropriate dosage and duration of effect, and interactions with other medicines. In practice, it is rarely prescribed or used nowadays due to the concerns indicated above.

Ginkgo biloba

Gingko is thought to stimulate blood flow in the brain and hence increase memory and alertness. Many trials have been done on its effectiveness. Some trials have proven positive about its benefit in slowing down the progression of early-stage Alzheimer’s disease. Studies have shown reasonable success in improving the symptoms of intermittent claudication, including increasing walking distances. Intermittent claudication is a condition common in people aged over 65 caused by poor circulation.

Symptoms include pain, cramps, and numbness in muscles, especially the calf. There is uncertainty about the long-term safety and efficacy of ginkgo biloba and whether it should be used long-term or intermittently. Side-effects are rare, the main ones being headaches and stomach upset. Diarrhoea, nausea, and vomiting occurred in less than 1 per cent of clinical trials. There is little information about its interaction with other drugs, but it has been shown to increase bleeding in drugs used to prevent clots. Therefore, it should not be taken with warfarin, aspirin or clopidogrel. It should not be used during pregnancy.


Lecithin reduces cholesterol by binding cholesterol and fats to water in the intestinal tract, hence reducing the absorption of cholesterol. It is not absorbed into the bloodstream as it passes straight through the digestive tract. Evidence indicates lecithin reduces LDL-cholesterol and can promote the HDL-cholesterol production.

A study published in the Hindawi Journal of Cholesterol in 2010 suggested that soy lecithin-rich diets can be used as an adjunct in the treatment of hypercholesterolaemia; however, no large enough study has yet been done, so further studies with a large number of patients should be done to find the ideal dose-response. A major source of lecithin is soy-bean oil. It can be purchased in powder or capsule form in pharmacies, health-food stores, and supermarkets.

Possible side-effects of oral peppermint oil are heartburn, nausea, abdominal pain, and dry mouth


Valerian is a herb used as a mild sedative to aid sleep. It is thought to work by increasing the neurotransmitter GABA in the brain. This is the same neurotransmitter that prescription sleeping tablets like zolpidem exert their effect on. Studies done so far do not conclusively confirm the effectiveness of valerian for the treatment of insomnia. Few side-effects have been reported.

Possible side-effects include headaches, dizziness, itching and gastrointestinal disturbance. Hangover the next morning is extremely rare. Valerian should not be taken by pregnant or breastfeeding women or by people on prescription-only sedatives such as benzodiazepines. Valerian is of little or no benefit to those suffering from long-term and chronic insomnia. However, it may be of benefit to those suffering from short-term sleep disturbance. Many of the common over-the-counter sleep aids contain valerian.

Peppermint oil

Peppermint oil is used to treat stomach bloating and stomach cramps, with research indicating its effectiveness and safety. It is available with or without prescription for irritable bowel syndrome (IBS). Colpermin is the popular brand in Ireland. Possible side-effects of oral peppermint oil orally are heartburn, nausea, abdominal pain, and dry mouth. Peppermint oil can rarely cause allergic reactions. Capsules containing peppermint oil are generally enteric-coated to reduce incidence of heartburn. If enteric-coated peppermint oil capsules are taken at the same time as antacids, the coating can break down too quickly.

Fish oils

Which is more important: Omega 3, 6 or 9? Omega-6 and 9s can be found abundantly in many of our common vegetable cooking oils, but not olive oil. Omegas 6 and 9 are common ingredients in many of the foods we eat. Western diets tend to be lacking in omega 3, so it is more important to supplement with omega 3 than omega 6 and 9. This is especially important for those who do not eat much fish.

Omega 3

Fish oil is recommended for a healthy diet because it contains the omega 3 fatty acids, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), precursors to eicosanoids that reduce inflammation throughout the body. Fish do not actually produce omega 3 fatty acids, but instead accumulate them from either consuming microalgae that produce these fatty acids, as is the case with fish like herring and sardines, or as is the case with fatty predatory fish, by eating prey fish that have accumulated omega 3 fatty acids from microalgae.

Cod liver oil is a form of fish oil derived from the liver of cod fish. It has high levels of the omega 3 fatty acids, EPA and DHA, and very high levels of vitamin A, vitamin D and vitamin E. Omega 3 fatty acids are primarily found in oily fish such as salmon, fresh tuna, mackerel, herring, sardines, and pilchards. We should eat two portions of fish per week, one of them oily.

Flaxseed oil, which is also known as linseed oil, is six times richer than most fish oils and its oil is perhaps the most widely-available botanical source of omega 3. Only 10 per cent of the population eat enough fish. Approximately 10 per cent of the Irish population eat sufficient oily fish to receive their necessary intake of omega 3, a new survey suggests. A 2012 IPSOS/MRBI survey found 89 per cent of Irish people do not eat enough salmon, fresh tuna, sardines, or trout to ensure that they receive the required dose of omega 3.


Omega 3 fish oils have in some studies been shown to stimulate blood circulation, increase the breakdown of fibrin, a compound involved in clot and scar formation, and may reduce blood pressure slightly. Some
evidence indicates that omega fatty acids reduce cholesterol levels, especially triglycerides. Regular intake may help reduce the risk of heart attack.

The American Heart Association recommends the consumption of 1 gram of fish oil daily, preferably by eating fish, for patients with coronary heart disease. Healthy women who said they ate fish five times a week or more had a 45 per cent lower risk of dying of heart disease over the next 16 years than healthy women who ate fish less than once a month, according to the Journal of the American Medical Association. An editorial in the May 15, 2000 issue of the American Journal of Cardiology claimed the time had come to add fish and fish oil supplements to the list of standard treatments for coronary heart disease.

High-strength omega 3 supplements such as Omacor are sometimes prescribed to lower triglycerides and are sometimes added to statin therapy when triglycerides are high. However, the HSE took omega 3 supplements off the PCRS reimbursement list for the GMS schemes (Medical Card and Drug Payment Schemes) due to the National Centre for Pharmoeconomics (NCPE) indicating the evidence of their overall benefits was not strong enough to warrant the HSE to pay for omega 3 supplements for treatment of triglycerides.

For example, one study quoted by the National Institute of Clinical Evidence (NICE in the UK) indicated for diabetics patients that while Omacor reduced triglycerides in the blood of diabetic patients by 5.6 per cent, there was no reduction in estimated CVD risk. However, there is significant evidence of the benefit for the secondary prevention of myocardial infarction (MI) for up to four years after the patient’s first MI.


Omega 3 fatty acids supplementation might be helpful in cases of depression and anxiety. Research has shown a link between the amount of fish people in different countries eat and the level of depression. It is thought that omega 3 may help the brain work more efficiently, so serotonin, which can boost your mood, has more of an effect. Evidence of their effects on mood is still not conclusive.


A safe dose

Medical nutritionists and the American government agency Food and Drug Administration declared that a dose of 3 grams (3,000mg) of omega 3 daily may be considered as generally safe. In Circulation, a panel of specialists of the American Heart Association published a study indicating that a daily dose of 8 grams (8,000mg) omega 3 daily is acceptable. The most frequent side-effect of omega 3 supplements is its fish after taste.


Most people do not have any digestion problems with fish oil supplements unless taken in high dosages. Some people may experience mild intestinal problems (ie, more than one bowel movement per day or liquid bowel movement). If that is the case, it is advisable to lower the dose.


In rare cases, the intake of high dosages (more than 3 grams per day) of omega-3 fatty acids could result in haematomas (bruises). However, this is very rare and a person would need to take extremely high doses for this to occur. Like aspirin, omega 3 fatty acids have an inhibiting effect on the coagulation of the blood; they inhibit the adherence of blood platelets (aggregation of blood platelets). Generally, this inhibiting effect on the aggregation of blood platelets is considered a benefit because it counteracts the formation of blood clots, thereby lowering the risks of heart attack or stroke. Yet, it could constitute a problem for people who are prone to getting bruises or for individuals who take anticoagulant medication (blood thinners) such as warfarin or NOACs.


The World Health Organisation (WHO) describes probiotics as “live organisms which when administered in adequate amounts confer a health benefit on the host”. Probiotics have some evidence that they boost the immune system and prevent gastrointestinal problems such as bloating, as well as preventing side-effects from antibiotics. However, bear in mind that the high sugar content of popular probiotic yogurts and drinks available in supermarkets counteracts the benefits of the probiotics.


Statins can reduce naturally-occurring coenzyme Q10 in the body. Co-enzyme Q10 has a role in muscle cell energy production, so some studies have proposed that a coenzyme Q10 supplement could reduce risk of muscle-related side-effects. However, scientific studies to determine how effective coenzyme Q10 is in reducing statin related muscle pain have mixed results. Some studies show a benefit, while other studies show no effect. Coenzyme Q10 rarely has any side-effects.


Cranberry may ease lower urinary tract infections. Cranberry may prevent the recurrence of urinary tract infections. Cranberry helps deodorise urine and fight E.coli and other bacteria. Cranberry juice available in supermarkets can help; however, it contains a lot of sugars which bacteria can feed on, so use lower-sugar versions.


Glucosamine and chondroitin supplements can provide pain relief for those suffering from joint pain. These chemicals are found naturally in cartilage and it is thought that taking these supplements may improve the condition of damaged cartilage. They may also slow down thinning of the cartilage. However, evidence of their effectiveness is questionable. For this reason, glucosamine was taken off the PCRS reimbursable list for
medical card and Drug Payment Scheme patients a few years ago.

Evening primrose oil

Evening primrose oil is traditionally used to relieve the discomforts of PMS (premenstrual syndrome), menstruation and endometriosis. By interfering with the production of inflammatory prostaglandins released during menstruation, the GLA in evening primrose oil is thought to help to lessen menstrual cramps. It may also minimise premenstrual breast tenderness, irritable bowel flare-ups and carbohydrate cravings, and help to control endometriosis-associated inflammation.

Evening primrose oil may ease the joint pain and swelling of rheumatoid arthritis and reduce the symptoms of the skin conditions eczema, acne, and rosacea. It may slow down diabetes-associated nerve damage and combat damage from multiple sclerosis. More evidence is probably needed to the effectiveness of evening primrose oil for these indications.

Part 2: Vitamins and minerals: Vitamin A/Beta carotene

Vitamin A helps you see in the dark. It helps eyes adjust to darkness after being exposed to bright light, like the headlights of an oncoming car at night. You can also thank vitamin A for healthy skin, strong bones, and a sound immune system. The vitamin itself shows up primarily in organ meats, but many fruits and vegetables contain beta-carotene and other carotenoids that are converted to vitamin A in the intestine. Eating foods rich in these substances may protect against heart disease and certain forms of cancer.

What foods are the best sources of vitamin A?

Orange, red, and dark green vegetables, and fruits are particularly rich in beta-carotene and the 50 other carotenoids that the body converts to vitamin A. Just one red pepper or half a cup of spinach contains enough to meet your daily requirement for vitamin A. Liver is by far the richest source of vitamin A — so rich that you probably should not eat it more than once a week. Fish and egg yolks are also packed with it, and some brands of milk are fortified with vitamin A to help bones absorb calcium.

Should I take a supplement?

No. You’re not likely to be deficient in the vitamin, and vitamin A supplements can easily give you a toxic dose, and while beta-carotene supplements are probably not harmful, they will not provide all the health benefits of carotenoid-rich foods. Researchers in Finland found that smokers who took vitamin A supplements were more likely to develop lung cancer.

Can I get too much vitamin A?

Yes. As little as 10,000mcg of vitamin A per day can cause birth defects in pregnant women and, over time, headaches, hair loss, and liver damage. But unless you are eating a lot of liver, it is hard to get that much from your diet. You cannot overdose on carotenoids, and your body will only convert what it needs to vitamin A.

B vitamins

The B vitamins are often referred to as the ‘energy’ vitamins, mainly because they are involved in energy release in the body. There are in fact eight different B vitamins, each with a different role in the body. The eight B vitamins are Vitamin B1, B2, B3, B5, B6, B7, B9 and B12. B vitamins help keep energy levels up, increase mental alertness, help memory, boost the immune system, and perhaps even help fight depression.

Many elderly people, vegetarians or people who are on strict diets do not get enough of these important vitamins. People who are stressed, eat out often, do not have a good balanced diet with plenty of fruit and veg, or abuse alcohol can also be deficient.

Types of B vitamins

Vitamin B1 is also called thiamine. It helps to regulate mental functions and nerve growth and can also help with memory. It also helps convert food to energy. Thiamine can be found in whole grains, beans, oranges, peas, peanut butter, pork, liver, and fish. A deficiency of vitamin B1 is common among people who abuse alcohol and alcoholics therefore need more thiamine. Alcohol reduces the absorption of thiamine in the body so vitamin B1 supplements are often needed by alcoholics. Heavy smokers or people who consume too many carbohydrates have a greater need for vitamin B1. Stress-related conditions will also deplete vitamin B reserves within the body, including vitamin B1. The recommended daily allowance of vitamin B1 is 1.4mg.

Vitamin B2 is also called riboflavin. It releases energy from foods, makes many of the body’s hormones and helps growth and development. It can be found in dairy products, green leafy vegetables, avocados, meat, beans, and nuts. A shortage of this vitamin may cause cracks and sores at the corners of the mouth, eye disorders, inflammation of the mouth and tongue, and skin lesions. The recommended daily allowance of vitamin B2 is 1.2mg.

Vitamin B3 is also called niacin and is used for over 50 body processes, including releasing energy from food, making hormones, removing toxins, and helping to keep cholesterol within the normal range. Niacin can be found in dairy products, meat, chicken, fish, beans, peas, nuts, and peanut butter. Vitamin B3 deficiency is rare in Ireland, with alcoholism being the most common cause.

The recommended daily allowance of vitamin B3 is 18mg. In high doses, available by prescription, niacin lowers LDL cholesterol and raises HDL cholesterol. Minor side-effects include flushing or tingling skin, itching, and headaches. More research is needed to prove the effectiveness of niacin in reducing cholesterol.

Vitamin B5 is also called pantothenic acid. It releases energy from food. It works with other B vitamins to help break down proteins, fats, and carbohydrates from food to give the body energy. It is also needed to make vitamin D and red blood cells. It can be found in liver, fish, chicken, beans, and whole grains. Deficiency of vitamin B5 can cause fatigue, headaches, nausea, tingling in the hands, depression and personality changes, and cardiac instability has been reported. The recommended daily allowance of vitamin B5 is 6mg.

Vitamin B6 is also known as pyridoxine. It can help prevent heart disease and reduce depression. We get pyridoxine by eating fish, chicken, potatoes, bananas, peas, beans, and avocados. Signs of vitamin B6 deficiency include dermatitis (skin inflammation), glossitis (a sore tongue), depression, confusion, and convulsions. The recommended daily allowance of vitamin B6 is 2mg. Deficiency in Ireland is rare, and only occurs in people with extremely poor diets.

Vitamin B7 is also called biotin. It helps to break down the proteins, carbohydrates, and fats into energy. We get biotin by eating liver, salmon, clams, eggs, milk, peanut butter, and bananas. Long-term antibiotic use can interfere with biotin production in the intestine and increase the risk of deficiency symptoms, such as dermatitis, depression, hair loss, anaemia, and nausea. Long-term use of antiepilepsy medications may also lead to biotin deficiency. The recommended daily allowance of vitamin B7 is 300mcg.

Vitamin B9 is more commonly called folic acid and helps cells grow and divide properly, prevents birth defects, and prevents heart disease. We get folic acid by eating dark green leafy veggies, avocados, beets, orange juice, beans, and liver. Women planning to conceive should take folic acid 400mcg daily prior to conception and for the first 12 weeks of pregnancy.

This prevents spina bifida in the new-born child. The normal recommended daily allowance of folic acid for all other adults is 100mcg. Most people assume folic acid is only needed during pregnancy. However, folic acid is important at all ages to properly form red blood cells and for our bodies to metabolise protein for energy.

Vitamin B12 is also called cobalamin. It breaks down proteins, carbohydrates, and fats to give energy. Vitamin B12, like the other B vitamins, is important for metabolism. It helps in the formation of red blood cells and in the maintenance of the central nervous system. It also helps prevent heart disease and combats depression. You can get cobalamin by eating eggs, milk, yogurt, chicken, fish, and meat.

Because vitamin B12 comes primarily from animal products, people who follow a strict vegetarian or vegan diet and do not consume eggs or dairy products may require vitamin B12 supplements. Those who have had surgery on specific parts of the small intestine or stomach are also prone to a deficiency if they do not take B12 supplements. Low levels of B12 can cause anaemia, numbness or tingling in the arms and legs, weakness, and loss of balance.

The recommended daily allowance of vitamin B12 is 6mcg. For people who are deficient in vitamin B12, their GP may decide to prescribe vitamin B12 injections. If this is the case, a 1000mcg cobalamin injection is generally given once-monthly via an intramuscular injection, often starting with a loading dose of weekly injection for the first few weeks if levels are very low.

A cause for low vitamin B12 levels can be pernicious anaemia, a blood disorder characterised by the inability of the body to properly utilise vitamin B12, deemed essential for the development of red blood cells. Most cases result from the lack of the gastric protein known as intrinsic factor (a genetic cause), without which vitamin B12 cannot be absorbed.

Vitamin C

Vitamin C is one of the most powerful of all known antioxidants. The damage done to cells by free radicals is acknowledged to be the cause of most age-related conditions, including diabetes, high blood pressure, vision problems, Alzheimer’s disease, heart disease and cancer. Antioxidants like vitamin C, E and A may help prevent or lessen the damage done by free radicals. Vitamin C is proven to boost the body’s immune system and help create antibodies, thus preventing illnesses like colds and flus. Vitamin C also helps the absorption of iron, thus helping oxygen transport in the body, so maintaining energy levels.

Vitamin B6 is also known as pyridoxine. It can help prevent heart disease and reduce depression

Vitamin E

Vitamin E works together with other antioxidants, such as vitamin C and selenium, to help prevent chronic illnesses such as diabetes and heart disease. Vitamin E captured the attention of cardiologists in 1993, when a Harvard University study showed that men who took vitamin E had a 35 per cent lower risk of heart disease than those who did not take the supplement. These results bolstered the theory that vitamin E helps keep heart problems at bay by preventing so-called bad cholesterol (LDL) from clogging up your arteries.

Vitamin E is most found in vegetable oils, nuts, fatty fish such as tuna and salmon, dark, leafy vegetables, and whole grains. Frying or cooking with a lot of oil could cause a loss of vitamin E. If you tend to skimp on vegetables, nuts, and whole grains, you may benefit from taking a vitamin E supplement.

Vitamin D

Your body also needs vitamin D to absorb calcium properly. Vitamin D is found in certain foods, including cod liver oil, oily fish such as sardines and herrings, margarine, and egg yolks. It is also made by your skin when in the sunlight. The National Osteoporosis Society recommends about 20 minutes of sun exposure to the face and arms, every day during the summer, to provide you with enough vitamin D for the year.

However, to reduce your risk of getting skin cancer, you should cover your skin between 11am and 3pm, and do not allow your skin to burn. Between 40-to-80 per cent of people over 65 have vitamin D deficiency in Ireland. Vitamin D deficiency also causes a mild muscle weakness and hence increases the risk of falls and hence fractures. Therefore, vitamin D supplementation is especially important in this age group.


New research has found that a daily supplement of 700-to-1,000IU of vitamin D reduces the risk of fractures from falls among older people by 19 per cent. The British Medical Journal shows that a dose of less than 700IU per day has no effect in reducing fractures. Research is also showing that vitamin D plays an important role in helping the immune system. It may also help prevent illnesses like diabetes, heart disease, rheumatoid arthritis and multiple sclerosis, as well as some forms of cancer.

Drug interactions

Some blood pressure medications called diuretics (ie, thiazides) can reduce the urinary excretion of vitamin D, hence increasing the risk of too much vitamin D. Some epilepsy medication such as phenytoin can reduce vitamin D levels.

Vitamin D in infants and children

Guidelines regarding vitamin D were released in 2010 by the Food Safety Authority of Ireland and the Department of Health. It is recommended that all infants, from birth to 12 months, whether breastfed or formula-fed, be given a daily supplement of 5µg (200IU) vitamin D. This should be provided by a supplement containing vitamin D exclusively. These guidelines were released because children (and adults) in Ireland have been found to have low levels of vitamin D. There has been an increase in the number of cases of rickets in Ireland in recent years.
Babies need vitamin D supplements for the following reasons:

  • Babies’ skin is very sensitive to the sun and should not be exposed to direct sunlight.
  • Babies’ food (breast milk, formula milk or solid foods) may not have enough vitamin D.
  • Between 0-12 months, babies grow very quickly and have a greater need for vitamin D to form strong bones.

Babies with African, Afro-Caribbean, Middle-Eastern or Indian ethnic backgrounds are at even higher risk of having low levels of vitamin D. Their stores of vitamin D may be particularly low when born, as their mothers’ skin may not be as efficient at making vitamin D from the low levels of sunlight experienced in Ireland.

Vitamin D3 (cholecalciferol) is the preferred form of vitamin D for infants. Liquid form is preferred. Products that contain other vitamins as well as vitamin D (such as multivitamin products) should not be used. Very high amounts of vitamin D are harmful. The recommended 5μg vitamin D a day is very safe for babies. Harmful effects only begin at levels that are five times higher than this recommended dose.

Research is also showing that vitamin D plays an important role in helping the immune system

Vitamin D and Covid-19 risk

The Irish Medical Journal (IMJ) highlighted the importance of vitamin D supplementation in Ireland due to the high percentage of deficiency and reported studies showing how vitamin D prevents respiratory infections, including Covid-19, and easing symptoms for those who get infected. (IMJ, April 2020) A study by the Irish Longitudinal Study on Ageing (TILDA) at Trinity College Dublin (TCD), as well as research from Technological University Dublin (published in IMJ in April 2020), indicated that vitamin D reduces risk of getting Covid-19 and helps fight it for those infected with Covid-19. TILDA is an ongoing study of people over the age of 50 in Ireland.

According to its report, ‘Vitamin D Deficiency in Ireland — Implications for Covid-19’, vitamin D plays an essential role in preventing respiratory infections, reducing antibiotic use, and boosting the immune system’s response to infections.

According to the research findings, people who do not have enough vitamin D in their body have a higher chance of getting a respiratory infection (chest infection) and pneumonia, as well as having little or no resistance to these infections. This points out that people who do not have enough vitamin D in their body can spread these infections due to their lack of resistance.

Taking vitamin D supplements may reduce risk of getting respiratory infections, including Covid-19. The findings indicate if Covid-19 infection occurs, vitamin D supplements may even ease symptoms and speed-up recovery times with these respiratory infections. The findings conclude that vitamin D may be able to slow down the spread of Covid-19 infection and help with resistance.


Eating a diet rich in calcium is important for maintaining healthy bones. Dairy products and green-leafed vegetables are good sources of calcium. Postmenopausal women with osteoporosis should aim to take 1,000mg of calcium every day, either in their diet or as a supplement. This can be obtained from 600ml of milk with either 50g of hard cheese (ie, cheddar or edam), one pot of yogurt, or 50g of sardines.

Care must be taken, as many dairy products are high in fat; however, the low-fat versions have the exact same calcium levels as full-fat versions. You should try not to drink fizzy drinks or have too much caffeine, salt, or animal protein such as beef, as these can affect the balance of calcium in the body.

Eating plenty of fruit and vegetables can help to cancel out the effects of too much protein in the diet. Smoking can have a harmful effect on bone strength and can also cause an early menopause. Calcium is one of the most common supplements prescribed in Ireland, mainly to prevent osteoporosis in older women.

Hair, skin and nails

Nutritional deficiencies can contribute to increased hair loss by weakening hair shafts that cause breakage to the hair and slow regrowth. Hair problems that are caused by nutritional deficiencies can be corrected by a good diet. The main nutrients involved in hair health include vitamin A, certain B vitamins, the vitamin biotin, vitamin C, copper, iron, zinc, protein, and water. Of all nutrients, biotin has the biggest impact on hair growth. It is found in food sources such as eggs and liver, however it will not reverse hair loss.

Lutein for eyes

Age-related macular degeneration (AMD) is thought to affect one-in-10 people over the age of 55. Over 60,000 people suffer from this condition in Ireland. Lutein, zeaxanthin, bilberry, and grapeseed are recommended to reduce the risk or slow the progression of AMD. They are available in over-the-counter supplements designed to reduce the risk and slow down the progression of AMD in at-risk patients. Evidence is mixed on their benefits.


Vitamin C helps the absorption of iron, so if you must take an iron supplement for anaemia, it is a good idea to take a vitamin C supplement or a fruit high in vitamin C at the same time. Antacids can reduce the absorption of iron by up to 30-to-40 per cent. Tea and coffee also reduce the absorption of iron, as tannins in tea and coffee bind to iron, reducing its absorption. Therefore, iron supplements should be taken at a different time to antacids and tea/coffee. Iron can reduce the absorption of some prescription medication.

For example, it reduces the absorption of bisphosphonates used for osteoporosis, and some commonly-used antibiotics, including fluoroquinolones (ie, ciprofloxacin) and tetracyclines (ie, minocycline, doxycycline). In fact, iron can reduce the absorption of tetracycline antibiotics by 50-to-90 per cent. Tetracyclines are mainly used for the treatment of chest infections (especially with bronchitis), acne and malaria prevention. Iron should be taken at least three hours apart from these medicines.


It is contained in foods such as chicken, meat, and fish. It is a major component of over 300 enzymes and plays a vital role in carbohydrate metabolism, protein synthesis, wound-healing, the immune system, digestion, sugar level control, and the senses of taste and smell.

Overload of fat-soluble vitamins

There are two general classes of vitamins, water-soluble and fat-soluble. Water-soluble vitamins include the B vitamins and vitamin C. They dissolve in water and are not stored by the body. Excess amounts are excreted in urine, which means that you cannot overdose on them. They must be replaced every day in our diet to provide a continuous supply. Fat-soluble vitamins include vitamin A, D, E and K. Fat-soluble vitamins are found mainly in fatty foods such as animal fats, including butter and lard, vegetable oils, dairy foods, liver, and oily fish.

Unlike water-soluble vitamins, they are not excreted when our body takes in too much; instead, they can build up in fat tissues and various organs in the body, such as the liver. Therefore, overdose is possible. Overdose of fat-soluble vitamins is very unlikely with food alone; however, some multivitamins have high levels of fat-soluble vitamins. Therefore, if taking several vitamin supplements, always check you are not doubling-up on fat-soluble vitamins. A common example of inadvertent overdose of vitamin A and D is taking cod liver oil with a multivitamin. This is because cod liver oil has high levels of vitamin A and D.

Instead of taking cod liver oil with a multivitamin, you can simply take a fish oil supplement, which has the benefits of omega 3 but has no vitamin A or D. Vitamin A is needed for the wellbeing of our eyes, bones, and reproductive organs. Signs of vitamin A toxicity include dry, itchy skin, headache, nausea, and loss of appetite. Overdose is dangerous in pregnant women, as it can damage the foetus. Vitamin D helps the hardening of bones and teeth and increases the absorption of calcium.

Overdose can cause nausea, weight loss and irritability. It can also damage the unborn foetus. There is, however, little evidence of toxicity with too much vitamin E and K.

Disclaimer: Brands mentioned in this article are meant as examples only and not meant as preference to other brands.

Written Eamonn Brady MPSI (Pharmacist). Whelehans Pharmacies, 38 Pearse St and Clonmore, Mullingar. Tel 04493 34591 (Pearse St) or 04493 10266 (Clonmore). http://www.whelehans.inet. Eamonn specialises in the supply of medicines and training needs of nursing homes throughout Ireland. Email