Meat, seafood and eggs are among the most nutrient-dense foods you can eat. These foods provide the best sources of fat-soluble vitamins A and  D, long-chain omega-3 fatty acids, Vitamin B12, iron, selenium and choline - all nutrients you can’t easily get from plant-based sources. Based on our human requirement for these essential nutrients, it is very difficult to eat 100% plant-based and have optimal health in the long term. 

At Functional Self, we recognise that everyone is different. We each have our own unique physiology and health profile, just as we each have our own set of beliefs and values. Overall, we support everyone who wants to optimise their health. If you do choose to eat a vegetarian or vegan diet, we won’t try to stop you. Depending on the diet you choose, you may need to consider supplementing certain key nutrients. 

Plant-based diets have gained popularity for a range of reasons, with veganism now considered mainstream and up to ⅓ of the population in the UK and US actively trying to reduce their meat or dairy intake. People often switch to a plant-based diet because of health reasons, environmental reasons, or because of an ethical or moral choice to avoid animal products. 

However there are many misconceptions about plant-based eating, starting with the idea that it is best for health.

Are plant-based diets healthy? 

While it is true that plants contain a wide range of polyphenols, antioxidants, and beneficial phytochemicals like
sulforaphane. this does not mean that eating an exclusively plant-based diet is healthy.  

You also need to be mindful of the antinutrients that plants contain, including the oxalates found in raw leafy greens, and lectins found in legumes like kidney beans, soy products. and peanuts. We all react to different antinutrients in different ways, and for some people these can trigger inflammation in the body (1)
, bloating, stomach pain and hormonal imbalances. Some antinutrients like oxalates can also disrupt our ability to absorb key nutrients such as calcium (2).

More crucially, without meat or fish in your diet you could be missing key nutrients that are essential to brain health, disease prevention, cell regeneration and immune function. Top of the list would be Omega-3 fatty acids, Vitamin B12 and fat-soluble Vitamins A and D, all of which are difficult to get on a fully plant-based diet. 

Omega-3 fatty acids 

Omega-3 fatty acids
are essential nutrients and are required for immune function, brain health and heart health (3). They also reduce cancer risk, improve cognition and learning and support healthy ageing (4)(5) .   While you can get omega-3 from plants, these usually contain the short chain omega-3 fat Alpha-Linolenic Acid (ALA).  Chia seeds, flaxseeds and sunflower seeds are good sources of ALA but these plant-based fats do not convert well into the long chain fatty acids EPA and DHA in the human body. This matters because the long chain fatty acids are the ones your body needs. There are also marine algae products available that contain some EPA and DHA. You can find out more about the difference between long chain and short chain fatty acids and why this is important in our recent guest blog Rosita Extra-Virgin Cod Liver Oil

Vitamin B12 

Getting adequate levels of
Vitamin B12 is also of major concern with plant-based diets. B12, also known as cobalamin is a complex molecule with cobalt at the centre. We need B12 to make blood cells, nerve cells and for DNA synthesis for every cell in the body, It is so important to our health that we are able to store it in the liver for 1 - 5 years, so it can take a long time after shifting to a plant-based diet to start to notice any symptoms of a deficiency. If a deficiency does develop, this means the body has typically entered the 3rd or 4th stage of  B12 deficiency which can be quite serious, in some cases leading to irreversible neurological damage (6). The symptoms of B12 deficiency include dizziness, fatigue, neurological and in some cases, psychiatric problems. 


Despite the misconception that you can get B12 from soil and plants, there are multiple studies showing that vegetarians and particularly vegans carry a higher risk of developing B12 deficiency (7)(8) . Plant-based sources of B12 such as mushrooms have been shown to have quite a low uptake in the body (9). Low levels of B12 in the diet is also linked with depression (10), which is likely to be related to the role it plays in the synthesis of neurotransmitters in the brain. If you are at risk for B12 deficiency it is a good idea to get your levels tested(11) and consider a supplement.

Fat soluble vitamins A and D 


As well as the Omega-3 fats and B12, Fat soluble vitamins A and D are also hard to come by on a plant-based diet. We need these fat soluble vitamins for healthy immune function, fertility, vision and skin. 

Cod Liver Oil is a particularly good source of naturally-occuring Vitamin A and Vitamin D in their most bioavailable forms. 


While we can get Vitamin D from the sun during the warmer months, it is not readily available in plant-based foods which can impact your health in the cooler seasons.). It is also very difficult for us to get enough Vitamin A from plant-based sources. 



Beta-Carotene (the precursor to Vitamin A) is found in orange root vegetables and some green leafy vegetables, however the conversion into Vitamin A has been shown to be very inefficient in the body. You would need to be eating several cups of carrots, kale, and sweet potato on a daily basis to be close to meeting your functional requirement for Vitamin A.



As well as these essential fats and vitamins, there are also lesser known nutrients such as
choline, found primarily in organ meats and egg yolks. Choline is required for proper cell function, fetal development and muscle function, and while it has been somewhat underappreciated as a nutrient, we need to ensure we are getting several servings of choline each week for optimum health. Wherever possible it is best to get your nutrients from whole foods, this is the most easily absorbable and bioavailable way to get what your body needs. 

Mindful eating and optimal health 

From an optimal health perspective, it is important to navigate these limitations of a plant-based diet and supplement where needed. We believe that becoming more mindful about your food and where it comes from is all part of the journey towards conscious eating and optimal health. We choose grass-fed meats and sustainable wild-caught fish as the most compassionate, morally-conscious and healthy options. 





1. Plant Lectins Activate the NLRP3 Inflammasome To Promote Inflammatory Disorders 
2. Oxalate content of foods and its effect on humans
3. Omega-3 Fatty Acids EPA and DHA: Health Benefits Throughout Life

4. Omega-3 Fatty Acids EPA and DHA: Health Benefits Throughout Life 
5. National Institutes of Health: Omega-3 Fatty Acids
6. Causes and Early Diagnosis of Vitamin B12 Deficiency

7. Serum concentrations of vitamin B12 and folate in British male omnivores, vegetarians, and vegans: results from a cross-sectional analysis of the EPIC-Oxford cohort study
8. The usefulness of holotranscobalamin in predicting vitamin B12 status in different clinical settings
9. The influence of a whole food vegan diet with Nori algae and wild mushrooms on selected blood parameters. 
10. Systematic review and meta-analysis of randomized placebo-controlled trials of folate and vitamin B12 for depression

11. *Note that as well as testing for B12 you should also be checking homocysteine (Hcy) levels in the blood, elevated Hcy is an indication of B12 deficiency. Vitamin B12 deficiency (Cobalamin deficiency)