What Nutritional Tests Are Useful In Long Covid?

Nutritional deficiencies are common with long Covid - find out which tests may help you on your road to recovery.

What Nutritional Tests Are Useful In Long Covid? photo

Nutritional testing for long Covid

Severe infection can leave people with nutritional deficiencies as the immune system has to work much harder during this time, which burns through nutrient reserves quickly. In turn, nutritional deficiencies can perpetuate post-viral fatigue and other long Covid symptoms. Both the immune system and the body’s energy production mechanisms need an array of nutrients to support the correct functioning of their finely-tuned processes. Recovery can be hindered if these deficiencies are not addressed. Testing your nutrient status can be a useful way to ascertain whether an individual could benefit from nutritional supplementation and it can also allow correct tailoring of dosage.

The following key tests are commonly considered by practitioners working in the field of long Covid and other post-viral conditions.

Vitamin D
  • Vitamin D plays a crucial role in regulating the immune system so that it responds appropriately to infection, allows us to tolerate non-threatening substances (such as food!) and switches off the inflammatory process once its job is done. Infections can leave us depleted in vitamin D and make it harder to get our immune system back in balance. In addition, low vitamin D levels can propagate the muscular aches and pains common in post-viral illness.
  • While we would ideally produce adequate amounts of vitamin D in our bodies from daily sunshine in Spring and Summer, the reality is that food and supplements are our main sources of vitamin D here in Northern latitudes. However, it’s almost impossible to obtain sufficient vitamin D from food alone.
  • Vitamin D supplements can be useful to sustain or replenish vitamin D levels in long Covid but, as vitamin D is a hormone, large doses are not advised unless an individual has a diagnosed depletion or deficiency.
  • Vitamin D testing can be ordered by GPs and is also available privately using finger-prick test kits.
Vitamin B12
  • Vitamin B12 is involved in both energy production and the nervous system, making it an important aspect to be considered in people with prolonged fatigue, brain fog, anxiety and other nervous system issues commonly found in Long Covid.
  • Standard vitamin B12 testing, while simple enough to carry out, does not easily give clear results regarding an individual’s B12 levels. The most common vitamin B12 test cannot discern between the inactive kind of B12 and the ‘active’ kind that the body can use.
  • A combination of tests, including MMA (methylmalonic acid) and homocysteine tests, can give a better picture of vitamin B12 levels. High levels of MMA and homocysteine on a blood test indicate B12 deficiency.Your GP might suggest these tests if serious deficiency is suspected and vitamin B12 injections are being considered.
  • Zinc regulates the balance of the immune system so that inflammatory responses can be turned on and off appropriately.
  • Zinc also plays a critical role in the health and function of the barrier tissues that form the first line of defence against incoming pathogens. This includes the health of the respiratory tract and the gastro-intestinal tract – zinc has been seen to protect against severe or prolonged Covid infection.
  • Low zinc levels are associated with some of the symptoms of Covid and long Covid, including loss of smell and taste, achy limbs and general weakness.
  • Good digestive health is needed to release zinc from food and the most bioavailable zinc is found in animal foods. People who have poor digestive health and eat a more vegan or vegetarian diet are at an increased risk of zinc deficiency.
  • High-dose zinc supplements must only be used if zinc levels are confirmed to be low, as too much zinc can also be problematic for the body, with potential interference with the balance between zinc and copper.
  • Testing zinc levels allows supplementation to be tailored to correct any deficiency.
  • The mineral magnesium is essential to support many of the body’s biochemical processes, not least of all those involved in energy production and cognitive function.
  • It’s difficult to test magnesium levels in the body accurately. This is because magnesium is found at different levels in various bodily substances, so testing the concentration of magnesium from one substance may not be an accurate reflection of your overall magnesium status. Serum magnesium levels, for example, do not appear to correlate with magnesium levels found in urine, salvia and plasma.
  • Concentrations of magnesium in red blood cells may be more closely related to a person’s magnesium status and it is the red blood cells that show more promise in testing in people with chronic fatigue conditions.
  • See our article on the importance of magnesium in long Covid.
Fatty acids
  • The health of the membranes surrounding the cells in our bodies can make a big difference to how well our cells receive the nutrients they need to release the energy they make. Cell membranes are made of fatty acids and these need to be the appropriate kinds of fatty acid in the right proportions.
  • A red blood cell test can identify the composition of the cell membranes and inform us about which kinds of fatty acids we are lacking.
  • An excess amount of Omega-6 may be found in the cell membranes, which might indicate a need for more Omega-3-rich foods. Omega-3 rich foods include oily fish such as sardines, anchovies, mackerel, herring and salmon. Plant-based omega-3 sources include chia and flaxseeds as well as algal oil supplements.
  • Conversely, a lack of Omega-6 fatty acids in the cell membranes might mean an Omega-6 oil such as GLA (Gamma Linolenic Acid) may be useful. GLA is found in evening primrose, blackcurrant seed oil, borage seed oil, and hemp seed oil.

Alshammari, E., 2021. Vitamin B12 Deficiency in COVID-19 Recovered Patients: Case Report. International Journal of Pharmaceutical Research (09752366), pp.482–485.

Das, U.N., 2021. ‘Cell Membrane Theory of Senescence’ and the Role of Bioactive Lipids in Aging, and Aging Associated Diseases and Their Therapeutic Implications. Biomolecules, 11(2), pp.1–40.

Martens, P. J., et al., 2020. Vitamin D’s Effect on Immune Function. Nutrients, 12(5).

Wessels, I., Rolles, B. and Rink, L., 2020. The Potential Impact of Zinc Supplementation on COVID-19 Pathogenesis. Frontiers in Immunology, 11, p.1712.

Workinger, J.L., Doyle, R.P. and Bortz, J., 2018. Challenges in the Diagnosis of Magnesium Status. Nutrients, 10(9).