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Vegan Diet & Nutritional Deficiencies

Written by Talia Cecchele

The number of people following a vegan diet in the UK has quadrupled in the last four years (1). More people are making the switch or eating more plant-based meals for both environmental and ethical reasons. Reducing consumption of meat products and dairy is known to have a positive impact on our health and that of the environment. Removing these foods from your diet completely however, can be trickier than it seems and if not done well can lead to multiple nutrient deficiencies.

What is a vegan diet?

A vegan diet excludes all meat (red meat, poultry, fish and seafood), dairy products, eggs and often honey or other animal-derived ingredients. It includes fruit and vegetables, cereals and grains, nuts and seeds, legumes and soy foods like tofu and tempeh.

What’s the risk of going vegan?

A well planned vegan diet can cover all the nutrients provided in a diet containing meat, dairy and eggs, but if not planned, there is a high risk of many nutrient deficiencies which can have a follow-on impact on your physical and mental health.

Some key nutrients needing to be considered are:

Vitamin B12:

Where can I find it? It is only found naturally in animal foods, so when following a vegan diet it is essential to consume fortified products such as plant-based milks or to take a supplement. Speak to your Dietitian or GP about this.

What happens if I don’t get enough? Vitamin B12 is needed for DNA formation, to make red blood cells and for nerves to conduct impulses. A deficiency can lead to a type of anaemia (pernicious), memory and vision loss and nerve damage.


Where can I find it? Plant-based sources include tofu, legumes, nuts, seeds, wholegrains, dried fruits and leafy green vegetables. These sources of iron (also known as non-haem iron) aren’t as easily absorbed as the iron in animal foods (haem iron), with an average absorption rate of <5% compared to 20% for haem iron. To boost the absorption of plant-based foods, include a food high in vitamin-C such as berries, broccoli, tomato, oranges or kiwi with your meal. Avoid drinking tea and coffee with meals as the tannins can inhibit iron absorption

What happens if I don’t get enough? Iron is a key component of haemoglobin which helps transport oxygen around the body and is a key nutrient for immunity. Deficiency can lead to anaemia, fatigue, weakness and brittle hair and nails.


Where can I find it? Calcium is found in plant-based foods like almonds, spinach, broccoli, tofu, dried figs and legumes and fortified foods (e.g. plant-based milk). Make sure your plant-based dairy alternatives are fortified with calcium, at least 100mg per 100ml.

What happens if I don’t get enough? Calcium is needed for strong bones and teeth, muscle contraction and nerve conduction. A deficiency can lead to brittle bones (osteoporosis) and stunted growth.

Omega-3 fats:

Where can I find it? Our body can’t make omega-3 fats and the omega-3’s found in animal products (like oily fish) differ to those found in plant-based foods. If you are following a vegan diet, including flaxseeds, walnuts, chia seeds, soy bean and canola oil will help to reach your target.

What happens if I don’t get enough? Omega-3 fats are necessary for optimal brain function and assist in preventing heart disease, high blood pressure and arthritis.


Where can I find it? Vegan sources include legumes, nuts, seeds, tofu & soy products like tempeh.

What happens if I don’t get enough? Protein is an essential building block for muscles, hair, skin and nails. It is needed for the production of enzymes, hormones and neurotransmitters (chemical messengers) and helps with satiety and keeping our immune system strong. If we don't eat enough protein, it can cause our muscles to break down into amino acids which are then used for energy.

Anything else to consider before going vegan?

Following a vegan diet is not for everyone and it is important to consider factors such as lifestyle, living location, food availability, income, medical history, activity levels and age before making a decision. The British Dietetic Association, Vegan Society and Dietetic Association Australia have fantastic free resources. If you are going to make the switch, I would recommend transitioning over a period of time to allow your body to adapt and to monitor any side-effects you might experience to determine if this way of eating is right for you.

If you are unsure about how to get a adequate nutrition on a vegan diet please book in with a Dietitian or speak to your GP.

1. The Vegan Society


Talia is a registered dietitian working in private practice and as an eating disorder specialist dietitian in London's leading private mental health hospital. As a freelance dietitian, Talia not only offers 1:1 consultations but can present at your workplace, create recipes or articles or host a cooking demonstration. To enquire please fill out a contact form.


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