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Many people have never heard of homocysteine, yet elevated levels of this naturally occurring amino acid can actually increase risk of some serious health conditions.


What is homocysteine?

Homocysteine (Hcy), a naturally occurring amino acid in the blood, is produced when another amino acid called methionine is broken down in the body. Methionine is found in meat and dairy products – foods eaten widely in the western world in large quantities. You could say that homocysteine is a byproduct of protein metabolism.

Discovered by Dr Kilmer McCully in 1968, he came to realise that high Hcy, not cholesterol, may predict arteriosclerosis and atherosclerosis leading to heart attacks and strokes. In fact, Hcy is thought to be one of the best markers relating to elevated risk of a number of serious health conditions, including cardiovascular disease, cancer and Alzheimer’s disease.

How is homocysteine made in the body?

Homocysteine metabolism is closely involved with methylation, a very complex process that happens over a billion times every second, and responsible for the health of almost all bodily systems. In a nutshell it refers to a process whereby methyl groups are added to, or taken away from, other molecules. Methylation is what converts methionine (from protein) into Hcy, and then it converts Hcy into other beneficial substances to stop it building up in the blood. This is done via two pathways – the first pathway converts Hcy into S-adenosyl methionine (or SAMe), which becomes a methyl donor too. The second pathway converts Hcy into glutathione, an important antioxidant in the body.

Measuring Hcy levels in the blood can reveal how effectively methylation is taking place. In simplistic terms, you could say that when your Hcy level is low you are methylating well and should be making adequate amounts of SAMe and glutathione. If your Hcy level is high, the reverse is likely to be true.

What causes high homocysteine?

  • Deficiencies in co-factors necessary for Hcy metabolism, such as vitamins B12, B6, folate and magnesium
  • Lifestyle factors such as alcohol, smoking, poor diet and lack of exercise
  • Health conditions including an underactive thyroid, Crohn’s disease and celiac disease
  • Low oestrogen levels
  • Long-term intake of certain medication, such as steroids, antacids and the contraceptive pill
  • Ageing
  • Being female
  • MTHFR gene mutation

Health conditions resulting from high homocysteine

  • Circulatory disease – high Hcy promotes oxidative damage to arteries, and increases oxidized LDL cholesterol, which attacks artery walls
  • Lower IQ, Dementia and Alzheimer’s disease – inflammation and free radicals caused by high homocysteine damage brain tissue. Also, lower level of B vitamins, TMG and SAMe associated with high homocysteine impact on memory and cognitive decline
  • Cancer – high Hcy is associated with low levels of glutathione, which is a powerful antioxidant in the body
  • Ageing – high Hcy increases oxidative damage and accelerates ageing
  • Pain and inflammation – high homocysteine promotes high levels of arachidonic acid and other inflammatory chemicals that trigger inflammation and pain
  • Glaucoma and macular degeneration – low levels of B12 and folate associated with high Hcy increase risk of eye disease.

Get tested and know your levels

Hcy levels can be checked via a simple blood test. Experts believe that the lowest risk is found in those with Hcy levels between 0 and 6.3, moderate risk in those with levels between 6.3 and 10, and the highest risk when Hcy is above 10. If Hcy is found to be elevated, the good news is that in most cases it can be reduced through a combination of diet and supplementary measures.

What you can do to reduce homocysteine levels?

  • Eat more liver, leafy greens, nuts and seeds – rich in B vitamins and minerals to support homocysteine metabolism
  • Eat more sulfur-rich foods like garlic and onions – they help make glutathione which can lower homocysteine levels
  • Supplement with gelatin and/or collagen powders – they contain glycine which helps balance out the methionine from protein, helping to break down homocysteine
  • Reduce caffeine and alcohol – excess amounts deplete B vitamins
  • Watch meat intake – too much for your needs can deliver excess methionine, driving up homocysteine levels
  • Don’t smoke – the carbon monoxide inactivates vitamin B6
  • Keep your digestion healthy and avoid using antacids – so you can absorb nutrients from your food
  • Sleep well – good sleep habits support methylation
  • Manage stress – stress hinders methylation
  • Exercise regularly – recent research has found that regular exercise reduces high homocysteine
  • Correct oestrogen deficiency – studies show that oestrogen lowers homocysteine

For further information about testing or correcting homocysteine levels, please get in touch.


Written by Emma Rushe

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