Over the last 4 years we have carried out hundreds of blood tests. During that time we have refined our testing to include the most common and important blood markers.

Some deficiencies have quick and obvious impacts, such as fatigue with vitamin B, whilst others are more insidious like the long-term effects on the brain of chronically low omega 3.

There are hundreds of minerals and elements that our body needs to work properly. We have listed the 5 most common vitamins and minerals we have found in our studies that people are deficient in and that have the most significant health impact.

1. Omega 3: 98.3% of tests for omega 3 have shown deficient levels.

46% of tests severely deficient.

High EPA and DHA levels are important

Yes, it’s massively important for skin, but it also makes up 60% of the grey matter in the brain. Low levels can be seen as dark shadows or holes in the brain on functional MRIs.

Low levels are linked to dementia (now the no.1 cause of death in the UK).

A recent study published looking at 2,220 people over 11 years showed that high omega 3 levels predicts an increased life expectancy of 5 years.

Food sources:

Mackerel, herring and tuna. Chia and flax produce ALA, but that is poorly converted in the body. Look out for omega 3 enriched eggs that are now more widely available – they have over 100mg per egg as opposed to 5-10mg.

How to spot a high quality omega 3:

If you are taking omega 3 supplements be aware that not all are equal. There are 6 different omega 3 molecules found in the body, but the important ones are EPA and DHA.  To correct low levels we have found that you need to aim for a combined EPA and DHA over 700mg. Be careful when you read the label as levels are often quoted as servings and in the small print it may say 3 capsules per serving.


Don’t believe the hype around flaxseed, it’s not much use to us humans. It needs to go through enzyme stages to be converted into EPA in the body and studies have shown we are not very good at that – in fact only 5% of flaxseed consumed is converted to EPA. Although I’m a fan of chia seeds the omega 3 is also of the ALA type that is not converted.

Vegan omega 3 supplements can be made in filtered tanks.

Signs you could be low:

Bumps on the upper arms “chicken skin” or keratosis pilaris.

Dry flaking skin.

Dandruff and dry hair.

2. We found low active B12 levels in 11%.

Quoted figures for UK are usually higher at 20%.

The patient on the right has vitamin B12 deficiency. Without B12 we cannot make red blood cells, nerves, or brain tissue. It leads to low energy, low mood and depression.

Low vitamin B12 has a devastating impact on the structure of the brain.

Vitamin B12 is a popular supplement as it has such a strong impact on energy levels. That said, there is no evidence that super high levels make any difference once a deficiency has been corrected.

11% equates to a whopping 5 million people walking around in the UK with a significant deficiency. B12 is a really common supplement for that reason, but if you are not testing to measure levels it still only equates to a 1:9 chance. That means that if you are taking vitamin B12 supplements without testing, then the chances are that you are wasting your money.

Vitamin B12 is essential and it can be a struggle to get enough if you are vegetarian or vegan, so it’s worth being safe and getting your levels checked.

If you have low B12 due to stomach problems affecting absorption you don’t need to have injections because you can get tablets that are absorbed by popping them under your tongue.

People who drink a lot of alcohol are at risk of deficiency. Some medications like antacids, metformin, and proton pump inhibitors all affect the absorption.

We also see a lot of small intestine bacterial overgrowth (SIBO) in clinic and this is also associated with low B12.

Active B12 versus normal B12

We measure active B12 in the blood, which is the form of B12 used by the body and is therefore the more important of the two to measure. If you have a problem converting B12 to the active from then B12 levels may be misdiagnosed. Although many studies have quoted B12 deficiency at around 20% we have found it to be 11%.


If you are worried you are low you can easily test, but remember it is better to test for active vitamin B12 rather than B12.

When choosing a supplement, pick the active form “methyl-cobalamin” or “hydroxocobalamin”. The cheap, common cyanocobalamin is poorly absorbed and less active.

Signs of low B12:

Flaky skin, white spots on your skin.

Pale lips and pale skin.

When levels are low it is really debilitating in terms of loss of concentration, memory, mood changes, fatigue, tingling hands or feet, burning feet.

3. Vitamin B9 (folate) deficiency was twice as common as B12 in our study at 22%.

Folate deficiency was much more common in women than men.

What’s folate used for?

Low folate causes the body to produce abnormal red blood cells that cannot carry oxygen properly, leading to significant tiredness and fatigue. It also causes impaired production of brain and nerve cells.

In our results we have found folate deficiency to be almost twice as common as vitamin B12. Both are equally important in the structure of important proteins, as well as the formation of healthy nerves and cells.

Both B12 and folate are essential in DNA synthesis and are important in rapid growth i.e. in pregnancy.

The MTHFR gene triggers the conversion of one form of folate into the main circulating form of folate. Is an important gene in the methyl cycle and has a large impact on heart health detoxification as well and mood and depression. See our blog on MTHFR.

Often we consume folic acid in our diets which is a synthetic product. In fact, the active folate is called methyl-tetra-hydro-folate. There is a well-studied gene whereby conversion of folate is significantly reduced, which has significant impacts on heart health, brain, mood and depression.


Avoid the cheap folic acid supplements if you are deficient. The activated form is methyl-tetra-hydro-folate so if you are going to take a supplement take one that works.

Signs of low folate:

Red and scaly skin. Fatigue, tiredness and lethargy.

Ulcers on the tongue or mucosa of the mouth. The chances are that these are in your intestine as well, but these are just the ones you can see.

4. Magnesium – the confusing blood test that means it’s low when it’s high…over 34%

Serum magnesium levels are the most incorrectly reported and misunderstood blood levels.

99% of magnesium in the body is found in red blood cells, not in the blood serum. In fact, it is very difficult to accurately measure true magnesium levels.

In a recent conversation with one of the experts in our laboratory we discussed this difficulty in measuring true magnesium levels. We’re not sure how helpful his view is that the only true measurement is by taking a biopsy of heart tissue!

Why does high magnesium in serum mean low overall body levels?

It is possible to do a special magnesium test on red blood cells that gives a more accurate idea of true body levels. When levels are low in the red blood cell it correlates with a high level in the serum. This may reflect the body trying to increase the transport and absorption of magnesium by circulating an above average level of magnesium.

We have found low levels of magnesium in 34% of tests, but this is likely to be under-estimating levels due to the difficulty in measuring it accurately.

Due to changes in our soils and farming, low magnesium is very common.

Low magnesium levels affect hundreds of enzymes in our body. It will often lead to low mood, low energy, and a difficulty in falling asleep, feeling wired and tired.

5. Vitamin D: 89% sub-optimal levels

If you are going to do one test this winter, do this one (read our blog on vitamin D).

Vitamin D

89% of blood tests have shown sub-optimal levels, with 47% in deficiency. This probably reflects our multi-ethnic patient group. Skin types of colour produce lower levels of vitamin D as does lower UV found in the UK.

This important fat soluble vitamin is actually a hormone linked to sun exposure and therefore to the seasons of the year.

Historically, the activity levels of our body would have matched the seasons. This in turn would be linked how much food we ate. However this evolutionary adaptation is now an issue that we need to address for our highly active lifestyles all year around.

Optimising safe levels of vitamin D is important as it can become toxic at high levels. Other vitamins and minerals should be checked at the same time. See our blog on taking vitamin D safely. We also measure iron levels by looking at ferritin and copper levels as well as assessing health by looking at lipid levels and the inflammatory marker CRP.

Sign of low vitamin D

Excessive sweating.

Achy joints and bones.

Sore muscles.

Low energy.

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