Supplements: Why, When and How

Confused if you should be taking supplements this winter? Let’s fix that.

First thing first, what are micronutrients and why do we need them?

Micronutrients, or simply vitamins and minerals, are vital for optimal health and the prevention of illness. They’re called micronutrients because we only need them in very small quantities compared to macronutrients (protein, fat and carbohydrates). Deficiencies in micronutrients can lead to serious diseases but it’s also important to make sure we have a sufficient intake of them to prevent illness, help us feel our best and even potentially extend our lives.

Can we get all the micronutrients we need from our food?

Technically yes but there’s not a simple answer to this question. We’re all individuals so our personal demands are different and the way we digest, absorb, and metabolise our food varies between each of us. In addition, we don’t eat food fresh from the ground, the types of food we eat can have varying levels of nutrients in and the nutritional value of some foods is even being impacted by climate change.1

supplementsSo do we need to take supplements?

The best way to know exactly what you need is to have the levels in your blood tested, particularly if you think you have any symptoms of low micronutrient levels. This way you know exactly what your levels are and therefore where you need to modify your diet or supplement to get these back up to healthy or optimum levels. A nutrition or health professional can support you; companies such as Thriva do at home testing kits for some micronutrients and one of their GPs will assess the results and advise you on the next steps.

Whilst in some cases supplementation can be crucial, research has shown that in certain circumstances supplementation, especially at high doses, can be dangerous and cause some negative side effects. Additionally, supplements often do not come in the form the body needs or in the synergistic ratios found in whole foods.

Although testing would be my recommended approach to know whether your diet is providing you with everything you need, these tests can be expensive and are best carried out regularly to monitor changes. With this in mind, there are a few simple rules you can follow to help ensure your micronutrient intake is as good as it can be and to reduce the chance that you will need to rely on supplements.

6 simple rules

  1. Nutrient density is king
    By nutrient density, I simply mean the number of nutrients per calorie in food. You only eat a certain amount of food per day, make it count by making sure what you eat contains as many nutrients as possible. For example, when trying to decide between certain foods think about the micronutrients that each will provide you and choose the one with the most.
  2. Plants, plants, plants
    They really are magic and should be a significant part of all your meals. Particularly green leafy greens such as spinach, kale, chard, watercress, and cabbage which are full of vitamins K, A, C, E, folate, magnesium, potassium and calcium as well as fibre, phytonutrients and chlorophyll.
  3. Eat the rainbow
    Variety is important, and it ensures your diet includes a broad spectrum of micronutrients. The more colours on your plate the more vitamins, minerals, phytonutrients and antioxidants you are consuming.
  4. Organic
    If you can, buy organic. It not only supports your health but the health of the soil and the planet too.
  5. Avoid drinking tea and coffee too soon after you’ve eaten
    Black teas and coffee contain tannins. These have some health benefits, but they can also bind to micronutrients such as iron, copper and zinc and reduce the absorption of these important minerals. It is, therefore, best to wait at least half an hour between your cup and your mealtimes.2,3

Are there certain circumstances when supplementation is recommended?greens

Vitamin D is made in the skin using sunlight. Since hours of daylight are limited in the UK during the wintertime, vitamin D deficiency is a real risk and can impact your health in many ways from your mood (SAD) to your immune system and bone health. I, therefore, recommend that you supplement with Vitamin D from between October to March in countries like the UK as it is unlikely that your diet alone will meet your body’s requirement of vitamin D through the winter.4 Taking it as a spray is best as the absorption rate is higher than capsules and make sure the supplement provides a minimum of 10 micrograms or 400 IU of vitamin D per day.

Certain lifestyle choices such as being vegetarian, or vegan may also mean it is not possible to reach the required daily intake of some nutrients such as iron and vitamin B12. Symptoms of B12 can be low energy, pins and needles and ulcers. In this case and if you follow a strict vegan diet, I would strongly recommend getting your levels tested and discussing your diet and lifestyle with a nutrition or health professional and exploring if supplementation would be best for you.

There are also certain times when the demand in the body may increase such as pregnancy and some illnesses. Asking for the help of a nutrition or health professional to support you will ensure that you are meeting your new body’s demands.

If I do need to supplement, how do I do it safely?

Be cautious if you chose to buy and take supplements. I recommend buying supplements from a reputable firm that is happy to discuss your needs as well as the quality of its products. Guidance from a healthcare practitioner can be useful to help you navigate which product may be best for you, especially if you have a health condition. Remember not all supplements are universally safe or suitable for everyone, so please ask a nutrition or healthcare professional if you have any concerns or questions. is also a great independent resource on supplementation, and you can also phone supplement companies directly and ask about their products.


  1. Soares, J.C., Santos, C.S., Carvalho, S.M.P. et al. (2019) Preserving the nutritional quality of crop plants under a changing climate: importance and strategies. Plant Soil. 443: 1–26.
  2. Milman, N.T. (2020) A Review of Nutrients and Compounds, Which Promote or Inhibit Intestinal Iron Absorption: Making a Platform for Dietary Measures That Can Reduce Iron Uptake in Patients with Genetic Haemochromatosis. Journal of Nutrition and Metabolism. 1-15.
  3. Petroski, W. and Minich, D.M. (2020) Is There Such a Thing as “Anti-Nutrients”? A Narrative Review of Perceived Problematic Plant Compounds. Nutrients. 12(10): 2929.
  4. Vitamins and minerals – Vitamin D – NHS (

anna humberAbout the author

Anna Humber (ANutr, MSc, BSc) is a Registered Associate Nutritionist and Healthcare Communications Consultant. She has a master’s degree in Clinical and Public Health Nutrition from UCL and 7 years’ experience working in healthcare communications and education. She specialises in sustainable and personalised nutrition and cares about helping people understand how they can live healthy and sustainable lives whilst also protecting our planet and enjoying themselves! You can find her on Instagram.