Major New Health Report Warns Of Nutritional Shortfalls With Plant-Based Diets

A new report[1] from the Health and Food Supplements Information Service (HSIS) reveals that the adoption of plant-based diets could result in a serious lack of vitamins, minerals and omega-3 fats in the diet, with worrying health consequences including a shortening of life expectancy.

The report, Plant Based Diets: Nutritional Challenges and Future Health Worries – An A-Z Analysis, reviewed data from 101 published studies, comprising of a total of 17,262 people, looking at the growing trend for plant-based diets and how this dietary choice is impacting nutrient intakes. In addition, a consumer omnibus was conducted to assess people’s dietary habits, understanding and views.

This latest HSIS report found that people on plant-based diets, vegans and vegetarians are typically at risk of dietary shortfalls for optimal wellbeing and health as well as undermining their micronutrient status which helps fuel health and wellbeing daily including seven key nutrients; Vitamin B12, vitamin D, Iron, Zinc, Iodine, Selenium, and Omega-3 fats.

Several of these nutrients such as iron, zinc and selenium are known to support normal immune function, essential for health and wellbeing, and particularly relevant at this time. While iodine and iron are important for supporting cognitive function, Vitamin D is key for optimal bone health, and omega-3 fats are vital for protecting the heart and brain. Chronically low levels of iron and B vitamins can also lead to tiredness and fatigue.

The HSIS consumer research also found that people who adopt plant-based diets often don’t do their research before switching to a plant-based diet, and this could be a key explanation for the low nutrient intakes seen across many international dietary surveys.

Consumer research findings

The HSIS consumer research revealed that a quarter of vegans and vegetarians say they had been diagnosed with a nutrient deficiency at some stage, mostly related to iron or vitamin D.

Hints of dietary problems are evident in the study with a quarter of people experiencing tiredness even after a good night’s sleep, and a fifth reporting depression. Low levels of B vitamins have been linked with these issues.

One quarter (25 per cent) report having dry skin while one in ten complained of hair loss or brittle nails. Vitamin A, zinc and selenium are all essential for the integrity of the hair and nails, and there are lower levels of these nutrients in plant-based diets.

Co-author of the report, GP, Dr Nisa Aslam, commented: “Awareness of nutrient shortfalls is very low, with HSIS research showing that fewer than a fifth of plant-based adherents identifying vitamin B12 as an issue, and no-one name-checking vitamin D despite the fact that nearly all major dietary sources of the ‘sunshine vitamin’ are animal or fish based. Awareness of other nutrients that are hard to obtain on plant-based diets; zinc, iodine and selenium is almost non-existent. That’s why taking a multivitamin and multimineral supplement is so vital.”

Co-author, nutritionist and adviser to HSIS, Dr Emma Derbyshire added: “With poor planning and research, and a worryingly low awareness of key nutrients, it’s really important that people who are thinking of switching to a vegan, vegetarian, flexitarian, plant-based diet or even those who are cutting out food groups should incorporate a daily multinutrient supplement into their diets.

“This can help make up nutrient shortfalls and ensure that people are more likely to meet their vitamin and mineral requirements. For those who avoid fish, an algae-based omega-3 supplement is also recommended since the particular omega-3 fats found in oily fish – called EPA and DHA – don’t exist in plant foods.”

Plant-based diet trend

A record 400,000 people worldwide signed up to Veganuary this year, and it’s been estimated that vegans and vegetarians will make up a quarter of the UK’s population by 2025[2]. Concern about nutrient gaps in plant-based diets is heightened given the recent surge in consumers ditching meat and dairy products.

Talking about the report finding, Dr Gill Jenkins, GP said: “Thousands more people are taking up plant-based diets, but a lack of planning often means they are risking deficiencies of key nutrients. Only a fifth of people are currently take a multivitamin or vitamin D – despite today’s stronger messages about topping up on vitamin D. Our advice would be – if you are vegan or vegetarian, or considering a plant-based diet, you should plan to take a daily multinutrient supplement plus a vegan source of omega-3s. And the same goes for those people cutting out food groups or indeed on a weight loss plan.”

Notes to Editors

Key nutrient deficiencies for those following plant-based diets

  1. Vitamin B12: Helps to metabolise energy and homocysteine, maintain a healthy nervous system, red blood cell formation, immune function, cell division as well as reducing tiredness and fatigue.
  2. Vitamin D: Helps absorption/utilisation of calcium and phosphorus and blood calcium levels, as well as maintaining normal bone, teeth, muscle and immune function.
  3. Iron: Contributes to normal energy metabolism, cognitive function, formation of red blood cells and haemoglobin, oxygen transport in the body and the reduction of tiredness and fatigue.
  4. Zinc: An important part of many enzymes, some of which have key roles in tissue growth, zinc is essential for fertility and reproduction. It helps the growth of immune cells and the body to produce its own antioxidant enzymes, as well as helping to keep hair, skin and nails healthy.
  5. Iodine: Essential for the manufacture of thyroid hormones, needed for normal growth and development, especially of the brain and central nervous system. Contributes to function of the immune system and helps keep skin healthy.
  6. Selenium: Contributes to sperm formation, is important for thyroid function, immunity, protecting cells from oxidative stress and inflammation, as well as helping to keep hair and nails healthy.
  7. Omega-3 fats: Omega-3 fats are essential fatty acids – eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). EPA and DHA are found in every cell membrane in the body and have a wide range of functions including helping to reduce triglyceride[3] levels in the blood; heart health; supporting brain function; helping to reduce blood pressure and helping to maintain eye health. EPA and DHA also inhibit the production of inflammatory chemicals in the body and have an anti-inflammatory effect in their own right. DHA is important in infant development, particularly in prematurely born infants. It is believed to be necessary to early eye and brain development. DHA is also thought to support brain development throughout childhood.

What is a plant-based diet?

The British Dietetic Association (BDA) defines a plant-based diet as one “based on foods derived from plants, including vegetables, wholegrains, legumes, nuts, seeds and fruits, with few or no animal products”.[4] Other ‘official’ definitions can be found in Table 1. Key to the BDA definition is that it simply spells out plant based in an uncomplicated way. The definition also clearly states that the plant-based diet can be devoid of animal products or can contain a few.

Table 1: Definitions of plant-based diets.

British Dietetic Association (2020)

“A plant-based diet is based on foods derived from plants, including vegetables, wholegrains, legumes, nuts, seeds and fruits, with few or no animal products”.


EAT-Lancet Commission (2019)

“The volume of approximately half a plate should be vegetables and fruits whilst the other half should consist of primarily whole grains, plant protein sources, unsaturated plant oils, and (optionally) modest amounts of animal sources of protein.”

McManus (2018) Harvard Medical School

“Plant-based or plant-forward eating patterns focus on foods primarily from plants. This includes not only fruits and vegetables, but also nuts, seeds, oils, whole grains, legumes, and beans. It doesn’t mean that you are vegetarian or vegan and never eat meat or dairy. Rather, you are proportionately choosing more of your foods from plant sources”.


Tuso et al. (2013) Definition for Physicians

“A regimen that encourages whole, plant-based foods and discourages meats, dairy products, and eggs as well as all refined and processed foods.”


What does plant-based eating look like?

People in the HSIS research study reflected the variety of opinion and practice. There are no right and wrong answers. A plant-based is not necessarily vegan or vegetarian though it may be. And it may indeed be flexitarian, perhaps eating animal source foods at some times and not at others whilst including lots of fruit and vegetables, beans, grains and so on.

A plant-based diet may contain fish in which case it is often referred to as pescatarian. A vegetarian diet would include dairy and eggs whilst a vegan diet would cut out all animal derived products, including meat, fish, dairy, eggs, honey and gelatine.

[1] Plant Based Diets – Nutritional Challenges and Future Health Worries – An A-Z Analysis; authored by Professor Robert Pickard, Dr Emma Derbyshire, Dr Gill Jenkins, Dr Nisa Aslam, Dr Pamela Mason; ahead of publication – summer 2020

[2] Future of Food report 2019

[3] High triglyceride levels cause health risks such as atherosclerosis, coronary artery disease and stroke