Supplements: How much is too much?

-Jun 3, Sara Palmer Hussey, PhD, Nutrition -

Whilst supplementing is a popular practice by women and men of all ages, we have noticed a worrying trend of people taking vast piles of supplements in the belief that any supplement must be good for them. But is that really the case? 

We all know that the modern diet doesn’t always contain enough nutrients to help us look and feel our best, despite our best intentions. Unfortunately, to get all the body needs for great skin, hair and nails supplementing is a necessity.  But there is too much of a good thing is most definitely a reality. 

Supplements often contain more than 100% of recommended daily intakes of vitamins and minerals. If this is added to what we are already integrating from our diets, we may exceed tolerable upper intake levels.

Is there a real risk of toxicity from supplements?

Excess amounts of any vitamins and minerals can lead to imbalances in the body that influence the absorption and function of other essential nutrients, as well as counterbalancing themselves. 

Vitamins are divided into fat-soluble and water-soluble. Fat-soluble vitamins, such as vitamins A, D, E and K, can be stored in the body, in fatty tissue and liver tissue, and released as needed. Water-soluble vitamins, such as the B vitamins and vitamin C, are not stored in the body and, therefore, a daily supply is needed.

As the body usually excretes excess water-soluble vitamins, we have often concluded that we need not worry about toxicity with these vitamins. However, recent studies have linked excess vitamin C to kidney stones and excess vitamin B6 to nerve problems. Although the levels at which toxicity can become a problem for these two nutrients lie over 2000% and 4000% of the recommended daily intake respectively, it is no longer unusual to see the levels of some nutrients in supplements reach levels close to those figures.

Folic acid is essential for preventing birth defects, but excess amounts interfere with the absorption of vitamin B12. With a tolerable upper level of just 1mg (250% of the recommended daily intake) and many foods now fortified with this nutrient, it is not impossible to exceed this value regularly.

Toxicity is a greater concern regarding fat-soluble vitamins, which can accumulate in fatty tissue over time and lead to a condition known as hypervitaminosis. Excess vitamin A during pregnancy can lead to birth defects, excess levels of vitamin E can increase the probability of haemorrhages and excess vitamin K can interfere with normal blood clotting.

With minerals, toxicity is also a concern. Excess calcium can impair kidney function and interfere with the absorption of iron and zinc. Excess selenium can lead to hair loss and nerve damage. Excess iron can interfere with zinc and copper absorption. Excess iodine can impair thyroid function.

If our diet is healthy and balanced, it is best not to take a supplement with any nutrient included at levels over 100% of the recommended daily allowance. It is also advisable to check the nutrient content of our diets and note whether any of the foods we habitually consume are fortified with certain vitamins and minerals (for example, in cereals, bread, soft drinks, health bars, multivitamins, etc.), which, together with any supplements we may be taking, could take our total intake over tolerable upper limits. It is obviously ill-advised to exceed the dosage recommendations specified on the packaging of any supplement.

Which nutrients are we likely to be deficient in?

So, in what nutrients are we likely to be deficient in our modern diet? The World Health Organization considers that more than 2 billion people worldwide suffer from vitamin and mineral deficiencies, primarily iodine, iron, vitamin A and zinc, with iron, zinc and iodine deficiencies being those most prevalent in the developed world.

According to the World Health Organisation, iron deficiency is the number one micronutrient deficiency in both developing and developed countries. “The major health consequences include poor pregnancy outcome, impaired physical and cognitive development, increased risk of morbidity in children and reduced work productivity in adults. Anaemia contributes to 20% of all maternal deaths.” In our diets, making sure we eat vitamin C (e.g. oranges and cruciferous veg) together with any plant source of iron (e.g. dark, leafy vegetables, lentils, chickpeas) will greatly enhance iron absorption, while the best sources are liver, meat, oysters and sardines.

It is estimated that over 2 billion people in the world today suffer from iodine deficiency, including about 50% of all Europeans. Iodine deficiency can result in thyroid problems, such as goiter, and mental disorders, such as cretinism. Having been almost completely depleted from our soils, the best sources of iodine now include seafood and iodised salt.

A lack of zinc can manifest in numerous ways as it affects so many organ systems, including the skin, gastrointestinal tract, the central nervous system, the immune system, the skeletal system and the reproductive system. Stores of zinc in the body are drastically depleted by stress and illness and requirements are increased by exercise and growth (e.g. during childhood and pregnancy). The best sources of zinc in our diet include oysters, meat, beans and nuts.

If we are able to identify specific nutritional deficiencies in our bodies and readdress them through diet, we will certainly feel improvements. 

What about supplementing with herbs? 

Certain safe herbal extracts that we may not integrate into our diets on a daily basis could also provide significant health benefits when taken as a daily supplement. These include turmeric, which helps address chronic inflammation, garlic, which has been shown to reduce the incidence of certain cancers, and milk thistle, which can be useful in addressing liver disorders.

The growing use of supplements in general reflects a wholesome interest in nutrition and the role it plays in preserving good health. It also reveals the desire to take a greater, more active responsibility for our own health. This trend is mirrored in sectors relating to other factors that influence good health, such as exercise and stress management. If supplementation is used wisely to safely guard against possible deficiencies in our diet as well as to maintain healthy levels of important nutrients in a targeted approach, it can certainly be an important tool in our quest for optimum health throughout our lives.

And, that’s certainly why supplementing sensibly, with a quality, clean all natural one that has been formulated by an expert to give you everything you need but nothing extra that you don’t, is such an useful tool for great health and wellbeing. There’s no need to take lots of other vitamins as well, your body doesn’t need them.


Love this? Find out here if your vitamin pills are made with toxic ingredients. Are you at risk of a vitamin D deficiency? – here’s how to spot the signs. And, if you’re in the mood for some probiotics, here’s how to make your own.

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