I eat a plant based diet - do I need supplements?

The good news

The good news is that a plant-based diet can provide the vast majority of nutrients your body needs to thrive. In fact, diets rich in vegetables, fruit, wholegrains, beans, lentils, nuts and seeds are consistently associated with a lower risk of heart disease, type 2 diabetes and some types of cancer,, while also supporting a healthy gut microbiome. So, by putting more plants on your plate, you're already doing something incredible for your health.

What to watch for

Every dietary pattern has its nutritional considerations. Vitamin D, for example, is recommended for everyone during autumn and winter in the UK, regardless of diet, while nutrients such as fibre and magnesium can sometimes fall short in an omnivorous diet. Similarly, on a plant-based diet, there are a handful of nutrients that are simply and more reliably met through fortified foods or supplements, and that's what I'll cover today.

Supplements are just one of the tools we can use to optimise our nutrition when food alone isn't always the most practical or reliable source, and you don't need a cupboard full of them. Once you know which nutrients to consider and where to get them, meeting your needs is usually far more straightforward than the online wellness world would have you believe.

So, if you're eating an increasingly or exclusively plant-based diet, let's look at the top 5 nutrients worth knowing about.

Vitamin B12

We may only need vitamin B12 in tiny amounts, but getting enough is critical for our long-term health. It helps keep our nerves healthy and is needed to make red blood cells and DNA.

Interestingly, vitamin B12 isn't made by plants or animals; it's made by microorganisms. Animals can obtain B12 through microbial production and feed supplementation, and it then becomes available to us in foods such as meat, dairy and eggs. Plants, however, aren't a reliable source, so if you don't eat animal products, you'll need to get your B12 from elsewhere.

Plant milks, breakfast cereals and nutritional yeast are commonly fortified with B12, while supplements provide another safe, cheap and reliable option. On a plant-based diet, you can choose one of the following strategies:

• Fortified foods two or three times over the course of a day, providing at least 3 micrograms in total
• A 10-50 microgram supplement per day, or
• A 2000 microgram supplement per week

The less frequently you take B12, the higher the dose needs to be, because our bodies absorb proportionally less from larger doses.

For people following a completely plant-based diet,  ensuring a reliable source of B12 is a key part of staying nutritionally well. If you eat some animal products, your intake will depend on the frequency and quantity you consume.

Vitamin D

Vitamin D is a little different from most nutrients because food isn't actually our main source. Although we can get small amounts from foods such as oily fish, egg yolks and mushrooms exposed to UV light, most is made in our skin in response to summer sunshine.

Between around October and March, however, sunlight in the UK doesn't contain enough UVB for our skin to make sufficient vitamin D. So, for most of us, the issue isn't what we eat, it's where we live.

UK government recommends that everyone considers taking 10 micrograms of vitamin D daily during autumn and winter. Some people are advised to supplement throughout the year, including those who:

• Spend very little time outdoors
• Regularly cover most of their skin
• Have darker skin

If you're vegan, choose a vegan-friendly supplement such as vitamin D3 derived from lichen rather than sheep's wool. Field Doctor's Vegan meals are fortified with a vegan vitamin D supplement.

Omega-3

Omega-3 fats support many aspects of our health, with particular roles in our heart, brain and eyes.

There are three different types of omega-3s to be aware of: ALA, EPA and DHA. Plant foods such as flaxseeds, chia seeds, walnuts and hemp seeds provide ALA, an essential short-chain omega-3 fat that we need to obtain from our diet. Our bodies can convert some of this ALA into the other longer-chain omega-3 fats, EPA and DHA, although this conversion can be limited. 

Regularly including ALA-rich foods is therefore a great foundation on a plant-based diet. Something as simple as a tablespoon of ground flaxseed stirred into porridge or 6 walnut halves sprinkled over cereal is an easy way to boost your intake.

You may have heard recommendations to regularly consume oily fish for omega-3. This is because oily fish are rich in EPA and DHA, but fish don't actually produce these fats themselves. Ultimately, they originate from marine microorganisms, including microalgae, and enter the food chain from there. If you don't eat fish, you may wish to consider going directly to the source and taking a sustainable algae-derived EPA and DHA supplement.

There's no specific recommended supplement dose for people following a fully plant-based diet, but around 450mg of combined EPA and DHA per day i is comparable with the amount of long-chain omega-3 provided by current UK fish recommendations.

Iodine

Iodine is needed to make thyroid hormones, which help regulate our metabolism and support normal growth and development. In the UK, adults are recommended to get 140 micrograms per day.

The amount of iodine in our food varies considerably depending on where and how it's produced. In the UK, milk and dairy products are the main source for many people, predominantly because iodine is added to cattle feed, which increases the iodine content of milk.

a completely plant-based diet or avoid dairy, iodine is therefore worth paying a little extra attention to. Some plant milks are now fortified with iodine, but not all, so check the label. If you're not regularly getting enough from fortified foods, a non-seaweed iodine supplement can provide a more reliable source.

Although seaweed can contain plenty of iodine, we don't recommend relying on it to meet your needs. Levels vary enormously between varieties and growing regions, meaning you could get far too little or far more than you need, with both scenarios interfering with healthy thyroid function.

Selenium

Selenium supports normal thyroid and immune function and helps protect our cells from damage. In the UK, the recommended daily intake is 60 micrograms for women and 75 micrograms for men.

It's found in both plant and animal foods, but levels in plants vary according to the selenium content of the soil. Brazil nuts can be particularly rich sources, alongside wholegrains, seeds and pulses, although their selenium content also varies.

If you follow a completely plant-based diet, it's worth making sure you have a reliable source. A vegan multivitamin containing selenium can be a convenient option, but avoid unnecessarily doubling up on selenium-containing supplements as very high intakes can be harmful.

Do I need a multivitamin?

If you eat a varied diet that's predominantly plant-based, you may not need anything beyond a vitamin D supplement during autumn and winter.

If you follow a completely plant-based diet, a supplement designed specifically for vegan nutrition can be a convenient way to cover several nutrients at once. These often combine vitamin B12 with vitamin D, iodine and selenium. Formulations vary, so always check the label to make sure it provides what you need.

So... what do I actually do?

Eating more plants is one of the most positive changes you can make for your overall health, and getting the nutrients you need doesn't need to be complicated.

Supplements aren't a sign that something is wrong with your diet. They're simply a useful tool for providing certain nutrients when food alone isn't always the most practical or reliable source. Whether you're enjoying a few more plant-based meals each week or following a completely plant-based diet, understanding which supplements are worth including as a regular part of your routine can help you enjoy all the benefits of eating more plants with confidence.

If you follow a completely plant-based diet, the key nutrients to prioritise are:

• Vitamin B12
• Vitamin D
• Omega-3 (EPA and DHA)
• Iodine
• Selenium

If you're new to a plant based diet and want some help ensuring yours is nutritionally balanced, working with a plant-based specialist dietitian can provide personalised guidance.

Please note, the recommendations in this article are intended as general guidance for healthy adults. Individual requirements may differ, particularly if you have an identified deficiency, a medical condition or have been advised to take a specific supplement or dose by a qualified healthcare professional.