Some People DO Need Vitamin Supplements

vitamin and mineral supplements

You may have heard some recent sweeping claims that everyone can get all the vitamins and minerals they need from their diet, and that multivitamins are a waste of time and money. If only this were true. The UK National Diet and Nutrition Surveys clearly show that significant numbers of adults and children obtain less than the minimum level that is needed to prevent nutritional deficiency diseases.

Reference nutrient intakes (RNIs)

Reference Nutrient Intakes (RNIs) are designed to meet the needs of 97.5% of the population. These amounts are calculated statistically, for each vitamin and mineral, from the estimated average requirement which meets the needs of 50% of the population. Around one in two people will need more than this level, and one in two will need less.

The important cut-off on which to focus is the lower reference nutrient intake (LRNI) which only meets the needs of an estimated 2.5% of the population. Most of us (97.5%) will need more than this minimal intake.


Anyone who consistently obtains less than the Lower Reference Nutrient Intake (LRNI) for any vitamin or mineral is likely to develop symptoms of deficiency as only 2.5% of people can get by with less than this amount.

You might think that few people are at risk of deficiency diseases in a country like the UK, where over-nutrition and obesity are growing problems. In fact, the National Diet and Nutrition Surveys clearly show that nutrient intakes are low for significant sections of the population. These low intakes are disguised by the average intakes, however.

Average intakes may seem OK …

As you can see for adult men and women in the chart below, the average female intake of iron, magnesium, potassium and selenium is below the RNI. For men, average intakes do not meet the RNI for magnesium, potassium or selenium.



Average intakes for vitamin A, vitamin C, folate and for the minerals calcium, iodine and zinc may seem acceptable – if not good – but an average is only an average. Some are getting more while others get significantly less. A worrying number of people do not even obtain the Lower RNI (LRNI) that only meets the needs of 2.5% of the population.



More than one in 10 men get less than the LRNI for vitamin A.

Over 1 in 10 adults get less than the LRNI for magnesium, potassium and selenium.

Nearly 25% of women have a low iron intake.

These low intakes are associated with nutritional deficiency diseases if sustained over a period of time and, in fact, 5% of older girls and adult women have iron-deficiency anaemia. Intakes are particularly worrying for adolescent girls, who need good intakes of vitamins and minerals to support optimal growth.



Almost one in two girls (46%) have worryingly low iron intakes, and over one in two are not getting enough magnesium.

Intakes below the LRNI were also found for folate and riboflavin (vitamin B2).

When it comes to vitamin D deficiency, blood tests showed evidence of low vitamin D status in 23% of adults aged 19 to 64 years and 22% children aged 11 to 18 years over the year as a whole. This increased to 40% for both in the winter months.

Not everyone gets all the nutrition they need from their food

To blithely say that we can get all the vitamins and minerals we need from our food, without checking the facts, is a misrepresentation of what actually happens in reality.

Diet should always come first, but if you are cutting back on food intake to lose weight, avoiding certain foods because of intolerances, skip meals because of a busy lifestyle, or simply have a poor appetite, then a multivitamin and mineral supplement acts as a nutritional safety net. Select one that supplies a sensible dose (around 100% of the recommended daily amount, or RDA, for as many micronutrients as possible) and avoid megadoses.

Click here to read my Expert Health Review of Multivitamin brands.

multivitamins coverTiredness … fatigue … dry skin … brittle nails … recurrent infections … hair loss… aches & pains … hormone imbalances

Do You Need A Multivitamin? My Quick Nutrition guide (46 pages) is currently free via this link  

Vitamin coverMy Essential Guide to Vitamins, Minerals and Herbal Supplements offers a complete overview of each vitamin, mineral, dietary oils and herbal remedy.

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About DrSarahBrewer

Dr Sarah Brewer MSc (Nutr Med), MA (Cantab), MB, BChir, RNutr, MBANT, CNHC qualified from Cambridge University with degrees in Natural Sciences, Medicine and Surgery. After working in general practice, she gained a Master's degree in Nutritional Medicine from the University of Surrey. Sarah is a registered Medical Doctor, a registered Nutritionist, a registered Nutritional Therapist and the award winning author of over 60 popular self-help books. Sarah's other websites are and

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6 thoughts on “Some People DO Need Vitamin Supplements

  • Candace

    Wow, that’s scary that so many people are deficient in these vitamins. I personally believe that people should be eating the right foods to attain these nutrients naturally, and I give 110% to provide myself and my family with what we need to stay healthy. However, I also understand that most lifestyles do not provide time for this. Not to mention dietary restrictions and food intolerances.
    I don’t think that anyone should be making blanket claims like “nobody needs vitamin supplements.” Everybody is different and leads a unique lifestyle. Do you have any tips on how someone can find out if they should be taking a vitamin supplement? This is a great post on the other perspective.

    • admin

      hi Candace, Diet should always come first – I have written a booklet to explain what each vitamin does and the symptoms that can occur if you don’t get sufficient, such as tiredness, lowered immunity, hormone imbalances, dry itchy skin, poor hair and nail quality. It’s available via but it sounds like you eat a good diet and are probably one of the ones who may not notice a difference in taking them. I first became interested in nutrition as a GP by prescribing vitamin supplements to patients with poor diets and seeing how well they responded – having convinced them diet was the root cause of their lack of energy they then started to eat more fruit and veg instead.

  • Marty

    In a day when food is processed and manufactured, it is hard to know what nutrients are being removed as preservatives and carcinogens are added.
    A good supplement seems a good idea when we are not always sure of our intake.
    It seems that we can’t always believe the ingredient labels. Thank you for informing us on nutrition.


  • Fadhil

    This is a very interesting and useful article for me.

    My father is now at stage 4 breast cancer plus prostate cancer. I have done a lot of reading around the web to search about supplement that could help my farther to get rid of the cancer.

    Now I’m giving a lot of vitamins and supplements to him and one of them is Vitamin C.

    I have a question, i heard some people say that consuming a lot of vitamin C is not good for our kidney.

    However, people are consuming it in various quantities.

    My questions is how much of the vitamin C quantity that actually bring the bad effect to our body?