The Best Supplements for a Low-Carb Diet: What do you really need?

panda-303949_640Ever wondered whether you should be taking supplements on a low-carb diet? Or which ones are the best? If you’ve just started a low-carb diet, you may be a bit overwhelmed by the amount of information out there – what you’re allowed to eat and drink, working out net carbs and macros, planning meals…the list goes on. In particular, you may have read about people taking supplements while on a low-carb diet, and be wondering what that’s all about. Well, wonder no longer – today I’m going to take you through the best supplements for a low-carb diet – which ones you need, and which ones are just going to give you really expensive urine.

Also, please note that this post is written primarily for people on a very low-carb diet (i.e., people attempting to achieve ketosis). In ketosis, your body sheds a lot more water-weight than some other carb-restricting diets, and flushes out more electrolytes as a result. Thus, the supplements mentioned here may be less relevant if you’re on a low-carb version of Paleo, for example.

Do I really need any supplements?

Honestly, that depends. It may be quite possible to get all the nutrients you need from the food you eat, particularly if you regularly eat nourishing broths. Also, if you’ve switched to a low-carb diet from a refined “white-carb” diet (think white bread, sugars, etc.), you’re likely eating far more healthily than you were before.

Having said that, it’s certainly not uncommon for people on a low-carb diet to start feeling run-down and lethargic as a result of the diuretic effects of a ketogenic diet causing them to lose electrolytes faster than they used to. So taking supplements can certainly help, especially if you’re still new to the lifestyle and haven’t yet figured out your eating/meal plans properly.

Some supplements, like fibre, are cheap, almost free of side-effects, and have only benefits, so there’s no reason not to take them. For others, it gets a little more complicated. So let’s take a look at individual supplements…


On a ketogenic diet, the recommended daily intake for sodium is around 5000mg. Sound like a lot? If you were eating a normal carb-rich diet, it would be. Sodium generallysalt-791655_1280 causes our bodies to retain more water, which can cause increased blood pressure (a bad thing).

But on a low-carb diet, your body is holding on to much less water, as it isn’t needed for glycogen storage. So increased sodium isn’t nearly the danger it’s made out to be.

As a result, you can safely up your daily sodium intake. In fact, you may well need to – low sodium is linked with adverse health outcomes, and symptoms such as headaches, muscle cramps, and tiredness.

Thankfully, sodium is basically the easiest nutrient to supplement – just add salt to your food. Processed meats, too, tend to be quite high in sodium. Just make sure that you’re drinking lots of water (which you should be on a keto diet), to continually flush excess sodium from your system.

Verdict: No extra supplements required, just add salt.


Similarly to sodium, on a ketogenic diet you should be aiming to get around 5000mg of Potassium a day. Low potassium can result in symptoms like fatigue, constipation, muscle weakness, numbness, and muscle cramps. Not fun!

So, is it safe to take potassium supplements? If you listen to the FDA (who seem unjustifiably paranoid about it), you might think not. The European Food Safety Authority, on the other hand, found that supplementing potassium up to 3000mg/day (on top of dietary intake of 3-4000mg/day) wasn’t linked with any adverse effects. So you should be pretty safe, as long as you don’t go overboard.

So do you need to supplement? That depends. You can get quite a lot of potassium from some dietary sources (avocados and spinach are great), but you may find that that’s still not enough. If that’s the case, supplementing is a good idea. You can easily buy products like nu-salt or lite-salt at the supermarket, or order it online. Both products replace sodium with potassium, so it’s an easy way to up your intake.

Verdict: Intake can be achieved with diet alone, but supplements will likely help.

IMPORTANT NOTE: If you have kidney problems, you may not be able to excrete excess potassium. So be very careful and see a doctor if you note adverse effects.


Magnesium is actually an incredibly important nutrient – it helps with bone building, it has anti-inflammatory properties, it helps keep blood-pressure down – the list of its beneficial effects goes on and on. Also, extremely importantly, it helps your body retain potassium, so if your magnesium levels are poor, you may end up taking far more potassium than you need.

So how much do you need? Far less than sodium and potassium – you only need around 400mg (note, that’s four HUNDRED, not thousand) per day. However, as with sodium and potassium, low levels of magnesium can lead to symptoms like weakness, muscle cramps, spasms, and heart arrhythmia. Again, not fun! So it’s important to keep your levels up (particularly after heavy drinking or exercise, which may cause you to lose more than otherwise).

Good dietary sources include flax and pumpkin seeds, seafood, and green leafy vegetables (e.g., spinach and chard). However, if you find that you’re still not getting enough, you may need to supplement. If that’s the case, you’re best off going for a “chelated” supplement, rather than an oxide, as oxides aren’t absorbed very well. Personally, I’ve only ever used magnesium glycinate, as it tends to absorb quite well and not lead to bowel upsets. Brand doesn’t matter, but Doctor’s Own from Amazon are rated quite highly.

Verdict: Possible to get through diet, but given its importance, worth supplementing.

IMPORTANT NOTE: As with potassium, if you have kidney problems it is very dangerous to experiment with magnesium supplementation. If you have kidney problems, or think you might, see a doctor first!


This is (hopefully) a pretty obvious and non-contentious one. Fiber is an incredibly important part of the digestive process, and most people don’t get enough of it. Recommended daily intakes are 25g for women; 38g for me. However, you’re unlikely to see negative effects by going above that, and very likely to experience discomfort if you don’t get enough. So there’s no real reason to not supplement your general intake.flax-seed-398067_640

On a ketogenic diet, you certainly can get enough fiber from dietary sources if you’re careful, but you have to be eating a lot of leafy greens. Common supplements include psyllium husk (think Metamucil) and flaxseed.

If you’re going to use a psyllium husk supplement like Metamucil, be very careful – many of them are significantly more carb-loaded than you might expect (standard orange-flavoured Metamucil, for example, has 16g sugar per 100g. Not great for low carb!).

On the other hand, flaxseed is basically a magical fiber wonder-supplement. It not only provides 27g fiber per 100g, but a whole bunch of other goodies, like Omega-3 fats, potassium, magnesium, protein. It’s great, seriously, and if you need extra fiber you should definitely be looking into flaxseed as a supplement.

Verdict: Why the hell wouldn’t you supplement fiber? Get some flaxseed into you now!

Fish Oil

Plenty of people love to take Fish Oil, which is full of Omega-3 fatty acids. Personally, I’ve never been a huge fan because I’m not great at swallowing pills/capsules, and they tend to be huge. However, don’t let that dissuade you – they ARE great for you.oil-315528_640

Fish oil has been shown to lower triglyceride levels and blood pressure, improve heart health, and potentially help with rheumatoid arthritis. While there isn’t necessarily a recommended daily intake for fish oil, you should be fine taking up to 3g/day.

Having said that, your best source of Omega-3 fatty acids is from fish itself – recent research has suggested that eating fish is more beneficial than taking supplements. But fish can be expensive to eat all the time, while supplements are cheap, so you’ll have to decide for yourself. Be careful though, as many supplements contain less than the claimed amounts of Omega-3s.

Verdict: Honestly, you can probably get most of what you need from flaxseed meal (I told you it was magical) and walnuts. Or eating fish itself. Supplement if it makes you feel better, but I’m not sold on it.

Vitamin D

Unlike sodium, potassium, and magnesium, all of which can be affected heavily by the diuretic effect of ketosis (thus requiring supplementation), vitamin D is pretty immune to increased peeing. That’s because it’s a fat-soluble vitamin, which means that it doesn’t get flushed as easily from the body as do water-soluble vitamins (like vitamins B and C).

What that means is that a low-carb diet, by itself, is unlikely to cause a vitamin D deficiency. However, plenty of people are vitamin D deficient, even though all you really need to do to avoid deficiency is to spend more time in the sun (we get 80-90% of it that way). So if you spend plenty of time in the sun, don’t worry about supplementing unless a doctor tells you to.

Given that vitamin D has a whole range of beneficial effects (check out WebMD’s information about it), it’s worth not being deficient in it. Your choices are either: a) Spend more time in the sun, or if that isn’t an option, b) Take a vitamin D supplement. Of these two, the sunlight one is by far the better option, but if you’re going to supplement, make sure that you’re using a vitamin D3 supplement rather than D2, as it’s more beneficial.

Having said that, there do seem to be possibly subjective beneficial effects from taking supplements, including decreased tiredness/increased mental alertness. Basically, give it a shot – if it works for you, great, if it doesn’t, get some more sun.

Verdict: You can’t supplement this with diet. You can get supplement pills, but going out in the sun is more fun (but also, skin cancer. Be careful).



So there you have it – a brief primer on the essential supplements for a low-carb diet. I didn’t cover multivitamins, because they’re so broad, but if you want to take them as well, check to see whether they provide any benefits to the substances mentioned in this article, and subtract that from what you need to supplement. I hope you found this informative, and if you think there are any other supplements I should cover, leave a comment below!

[adinserter block="4"]

About Dominic

5 thoughts on “The Best Supplements for a Low-Carb Diet: What do you really need?

  1. Hi Dominic. I’ve read some of your posts and I can tell this niche is really your areas of expertise. You’ll definitely be helping lots of people with your knowledge. Ok, back to the topic. My mom once asked me to try take the Fish oil because she said it can somehow cure a headache. She used to have a headache quite regularly and once she began taking the fish oil it works like a charm. I also have a headache quite often so, I decided to try it and once I swallowed, that (like the one on the picture above just a bit bigger) stuck in my throat and I panicked. Ever since that, I swear I’m not going to take that again no matter what. Btw, is it true that it can cure a headache?

    1. Hi Meina,

      Thanks for the lovely feedback! And I totally sympathise with the failure to swallow fish oil capsules – they’re generally pretty huge. You can get it just as oil, but…it’s generally pretty disgusting. If you struggle with the capsules, you’re probably better off just trying to eat plenty of oil fish (mackeral, salmon, etc.).

      Regarding your question – I couldn’t find anything directly related to a single fish oil capsule relieving a headache (and I can’t think why it would, other than via placebo effect). However, there is pretty good evidence that high levels of omega-3 fatty acids in general are good for reducing chronic headaches/migraines ( So if you suffer chronically, increase Omega-3 intake (via supplements or diet) and decrease omega-6. Hope that helps!

  2. Thanks for the info. I’ve read it but only managed to understand some of it. Based on the research that had been done, I think fish oil does help a bit in reducing severe headache. I’ll just stick to eating salmon then.

  3. Hi Dom,
    Great article and valuable information for those that want to watch their diet without sacrificing nutrients that the body needs. Although I am not diabetic, I know this post will help anyone that may have and not so well informed on helping their condition. Keep up the great work.


Leave a Reply

Your email address will not be published. Required fields are marked *