• Jenny

Do You Need Supplements on a Plant Based Diet? - Nutrition Series

Updated: Sep 22, 2019

As with many topics surrounding diet and healthy living, the subject of whether or not you need supplements on a plant based diet can be a bit of a controversial one. On the one hand, you get people who say that you 100% need to supplement and if you don’t you will be deficient in everything and die. On the other hand, you have people who say that you can get absolutely everything you need from a whole food plant based diet and that supplementing is completely unnecessary. Ultimately you need to do what you think is right for you, but I thought I’d set out some information here to hopefully make it a bit easier for you!

Do I get everything I need from whole plant foods?

The short answer, depending on what you eat, is possibly not. You will likely be getting nearly everything you need, but maybe not quite. Now, that is not because a whole food plant based diet isn’t healthy or natural (the opposite is true) but because of the way food is commercially produced, depletion of minerals in the soil, and our lifestyle in general. The same applies to those eating a standard diet - vitamin and mineral deficiency isn't something that should only concern vegans! This doesn’t affect all vitamins and minerals, and you really don’t need to worry about the vast majority if you are eating a varied whole food plant based diet. There are, however, three supplements that you might want to consider taking unless you are being particularly careful to include sufficient quantities in your diet: vitamin B12; iodine; and vitamin D.

Vitamin B12

As I wrote about in a separate blog post on B12, modern sanitation has meant that we are rarely exposed to the bacteria that produce B12 in a natural way, whether you are vegan or not! It is possible to ensure that you get enough B12 by eating fortified foods (fortified plant milks, nutritional yeast and fortified breakfast cereals), but B12 deficiency is nasty so Jonny and I decided that rather than risk it we would take a daily supplement (you can also get weekly ones).


Iodine is a mineral which is necessary for thyroid function and helps to regulate how energy is produced and used in the body. Dietary iodine intake will depend on the iodine content of the soil in which plants are grown. In general, the closer to the sea they are grown, the higher the iodine content. It is, however, hard to judge this in your diet. A good source of iodine for vegans is seaweed. Since this grows in the sea, it is a good source of iodine. There are a number of different types of edible seaweed, including nori, dulse and kelp. One word of warning – if you are going to rely on seaweed for your iodine intake (or just something to bear in mind if you eat seaweed), remember that it is possible to get too much iodine. Kelp tends to absorb much more iodine than other types of seaweed, so use it sparingly and keep an eye on iodine content!

Iodine deficiency can cause issues with your thyroid, but so can consuming too much iodine. It is also possible to get iodine poisoning, which causes a number of unpleasant symptoms ranging from mild to sever depending on the amount of iodine consumed.

We try to avoid having to worry too much about our iodine intake by taking a supplement. We do occasionally eat seaweed, so on those days we just skip the supplement!

Vitamin D

Vitamin D is an interesting one. We need it for healthy bones, teeth and muscles, as well as for other functions in our bodies. We can produce vitamin D ourselves, but only when our skin is exposed to sufficient sunlight. If, like us, you live somewhere like the UK where the weather is… let’s say… less than ideal, you will probably need to take a vitamin D supplement (particularly during the winter months, and also during the other months if you wear a lot of sun block).

There are certain fortified foods that contain vitamin D (including plant milks and cereals), but if you are not getting enough direct sunlight (at least 20 minutes a day), it is probably best to take a supplement rather than rely on dietary sources. Be careful though, there are two different types of supplements, D2 and D3. Our bodies can use both, but the difference will be the source of the vitamin. D2 is always vegan but D3 sometimes isn’t. You should always check the source of your supplements before buying them!

Should I take a multivitamin?

This is up to you to be honest. We don’t, mostly because we eat an extremely varied diet that is centred around whole foods (lots of whole grains, beans, lentils, and lots of veggies!) and we confident that we get what we need. We occasionally supplement specific vitamins and minerals (e.g. if we have eaten foods that are high in oxalates we will sometimes take a calcium supplement just to be sure) but rarely, if ever, take a multivitamin. If you want to take one just to be on the safe side that is fine, but just check which vitamins and minerals they actually contain (it varies) and check the quantities (some of them are crazy high in certain vitamins and minerals – this can be a problem, particularly for fat-soluble vitamins which are stored by your body, meaning you can have too much, which can cause serious side effects!).

In general, I think it is best to get your vitamins and minerals the way nature intended (as far as possible) – through fresh, whole, plant based foods! In fact, I believe that health conscious vegans get a wider variety of vitamins and minerals than those who eat a standard diet, as we typically eat a wider variety of fruits, veggies and healthy foods! When it comes to the vitamins and minerals listed in this article though, Jonny and I err on the side of caution and take a sensible dose supplement to ensure we get enough in our diets (without getting too much!).


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