Supplements: what we need to know and when we might need them!

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    A question that I get asked, at nearly every session is “Should I be taking supplements? which ones should I be taking?”

    The answer to this question will vary depending on who I am talking to, not a straight answer I know but let me give you some context! 

    What we require changes as we age or our life stage. Children and older adults will have a need for more protein than adults, pregnant women or those breastfeeding will have a greater need also. 

    However, we should try to get most of the nutrients we need from a varied diet. Some of the reasons for this are:

    • By eating foods, we also gain other micronutrients and macronutrients like fibre too!
    • Those nutrients in foods tend to be more bioavailable i.e. easier for our body to absorb and use
    • By aiming to eat a range of foods, this helps up make healthier behaviour changes that hopefully remain long after the bottle of supplements are gone.
    • Supplements can be costly compared to foods

    Still there are instances, where supplements can be useful for maintaining and improving our health in general and then there are those that need to be taken because of a condition or deficiency.

    Supplements on spoon

    Here are some supplements most of us need to take:

    Here are some examples where supplementation has been advised for the general public:

    Vitamin D is important for our musculoskeletal and immune health. However, most Irish people are deficient in Vitamin D due to the lack of sun and its source from foods. The FSAI recommend that

    • For healthy children (5-11 years) a daily vitamin D supplement containing 10 µg (400 IU)  during extended winter (end of October to March) for those of fair-skinned ethnicity throughout the full year for those of darker-skinned ethnicity.
    • For healthy teenagers and adults (12-65 years) a daily vitamin D supplement containing 15 µg (600 IU) during extended winter (end of October to March) for those of fair-skinned ethnicity throughout the full year for those of darker-skinned ethnicity throughout the full year for those who are pregnant, regardless of ethnicity (1).

    Folic Acid (Vitamin B9) if you are pregnant or planning to get pregnant, a daily folic acid supplement of 400 micrograms is recommended. Its preferable to take folic acid for at least 14 weeks before you become pregnant and to continue taking it for at least the first 12 weeks of pregnancy (2). 

    Some other reasons why supplementation maybe needed:

    There are specific cases where supplementation maybe advised, these may include:

    • Medical conditions for example iron deficiency anaemia. You maybe be advised by your doctor to take a supplement to ensure that you are  not at risk of deficiency.
    • Certain medications which you may need to take, may impact a vitamin or mineral level within the body. Therefore, it’s important to talk to your pharmacist about possible drug-nutrient interactions depending on the type of medication you are taking (3). 
    • Blood tests show that you are deficient in a specific nutrient e.g. Iron, B12 and then a specific supplement will be advised by your doctor. 
    • Following a Vegan or vegetarian diet – while following a plant-based diet can support healthy living; you may need to take additional care to ensure that that your plant-based diet is meeting all your nutritional needs. Especially nutrients like Vitamin B12, Iodine, Calcium, Iron and Omega 3 essential fatty acids (4).
    Supplements in hand

    There are risks to taking supplements.

    Some considerations to be aware of, if you are taking supplements:

    • If you need to take a supplement its important to ensure that you take supplements at the recommended doses and to be careful that if you take more than one supplement that you are not doubling up. This is often the case if you are also taking a multivitamin, you could be inadvertently taking more than recommended. 
    • More is not better when it comes to supplements, your body in some cases can store excess e.g. fat-soluble vitamins (Vitamins A, D, E and K) and could be harmful to your health rather than helping! So, make sure you get professional advice on the amount, for how long, and what dietary changes you could make to help you get the nutrients you need from what you eat.
    • Quality can vary from brand to brand – always purchase from a reputable source. Read the label as within the EU there are specific requirements regarding labelling and the health claims that can be made on products to help protect consumers.

    The British Dietetic Association (BDA) also outline some additional risks as consumers in their Supplement Resource that we need to be mindful of:

    • If you are pregnant you should not take fish liver oil as it contains vitamin A, which can be harmful to babies in large amounts
    • If you have cardiovascular disease, avoid vitamin E supplements as these can increase the risk of further heart attacks
    • Effervescent (fizzy) vitamin supplements contain approximately a gram of salt per tablet. So you might want to consider changing to a non-effervescent alternative, especially if you have been advised to limit your salt intake
    • The term ‘natural’ doesn’t always mean safe. Some natural botanical products can damage the liver. The safety of a supplement depends on a number of factors, including how it is prepared, how it works in the body and how much of it you consume.
    fish oils

    While supplements have a place in helping prevent deficiency when advised by a medical professional, this is different to taking supplements to enhance our health. Eating a varied diet is the best approach to enhancing our health, if for one of the reasons above we need to supplement then do so with care and always get professional advice. 


    1. FSAI (2023) Vitamin D: Scientific Recommendations for 5 to 65 Year Olds Living in Ireland. rep. Food Safety Authority of Ireland. Available at:
    2. Folic acid: Vitamin recommended for women, Available at:
    3. Mohn, E. et al. (2018) ‘Evidence of drug–nutrient interactions with chronic use of commonly prescribed medications: An update’, Pharmaceutics, 10(1), p. 36. doi:10.3390/pharmaceutics10010036.
    4. BDA (2023) Vegetarian, vegan and plant-based diet, Available at:
    5. BDA (2023a) Supplements, Home. Available at: