Hyperhomocysteinemia (high blood levels of homocysteine) is an emerging cardiovascular risk
factor, which may depend on nutrient deficiencies in the diet.
Some nutrients (choline,
betaine and some B-group vitamins) are essential to keep
homocysteine blood levels under control and for this
reason they can boast the Health Claim "contributes to normal
homocysteine metabolism " , authorized by the European Food
Safety Authority (EFSA) on the basis of substantial scientific
evidence.
Homocysteine is a
non-protein amino acid biosynthesized during metabolism of
methionine, an essential sulfur amino acid that is taken with diet.
The blood level of
homocysteine is the result of a close relationship between dietary
habits and genetic predisposing factors and an high level of
homocysteine in the blood may depend on the lack of folate and other
B-group vitamins in the diet.
Hyperhomocysteinemia (high
blood levels of homocysteine) is now considered an emerging, strong
and independent cardiovascular risk factor , associated with the
onset of cardiovascular disease (coronary atherosclerosis and
myocardial infarction), cerebrovascular disease (stroke) and
peripheral vascular disease (arterial and venous thrombosis).
It is estimated that
people with hyperhomocysteinemia have about twice the normal risk of
developing cardiovascular disease and this condition is now
recognized by the scientific community as a further risk factor in
addition to other well-known cardiovascular risk factors
(hypertension, diabetes mellitus, high cholesterol levels, smoking).
In addition, some evidence
suggests that people with elevated homocysteine levels have twice the
normal risk of developing Alzheimer's disease.
A review of the scientific
researchers of the Iberoamerican Cochrane Network, aimed to evaluate
the clinical efficacy of interventions designed to reduce blood
homocysteine levels in people with or without pre-existing
cardiovascular disease, showed, for the moment, no evidence in
support of homocysteine lowering treatment for the prevention
of cardiovascular events.
Hyperhomocysteinemia,
however, remains a condition associated with an increased
cardiovascular risk, and it’s considered a cardiovascular risk
marker in various screening programs: it is therefore important to
know what are the nutrients (vitamins and others) that help to keep
under control blood homocysteine levels and whose deficiency can be
associated with hyperhomocysteinemia.
Some nutrients, after
European Food Safety Authority (EFSA) examination and authorization,
can boast the health claim "contributes to normal homocysteine
metabolism".
Let's see below what they
are, how they work and where they can be found (food sources).
Betaine: It originates
from choline oxidation in mammals and can act as a methyl group donor
in the homocysteine remethylation process in the liver.
This mechanism of action
supports the evidence from human studies that shows a significant
lowering of blood homocysteine levels after administration of
betaine.
It should be remembered,
however, that a daily dose of 6 g of betaine seems to lead to an
increase in total blood cholesterol and LDL-cholesterol, which
doesn’t occur at significantly lower doses (4 g /day). For this
reason an additional warning
on the label of betaine supplements is necessary.
Food sources of
betaine: Quinoa, beetroot, broccoli , spinach, cereals and seafood.
Choline: It is a precursor
of betaine, whose mechanism of action on homocysteine metabolism
is known.
For this reason, a
choline-deficient diet is associated with elevated homocysteine
levels and studies showed an inverse correlation between
dietary choline intake and blood homocysteine levels.
Food sources of choline:
egg yolk, soybeans, liver, veal and turkey, lecithin.
Folic acid and folates: 5
-methyl-tetrahydrofolate is an important intermediate of folate-dependent metabolic pathway for the production of methionine from
homocysteine.
Food sources of folic acid
and folate: offal (kidney , liver) , green leafy vegetables (
lettuce , spinach, broccoli ), legumes and eggs.
Vitamin B12:
methylcobalamin, a coenzyme form of vitamin B12 , is also involved in
the methylation of homocysteine to methionine, which requires
as cofactors both folate and vitamin B12.
Food Sources of Vitamin
B12: animal foods, especially liver.
Vitamin B6: This nutrient
is essential for an alternative metabolic pathway for remethylation
of homocysteine to methionine (transsulfuration pathway).
Food sources of Vitamin
B6: foods containing whole grain flours , some tropical fruits
(avocados, bananas), hazelnuts , wheat germ, brewer's yeast and
carrots, but also rice, lentils, tuna, salmon and shrimp.
In conclusion,
deficiency of folate and folic acid, vitamin B12, vitamin B6,
choline and betaine is the basis of an altered methylation of
homocysteine.
Homocysteine, after an initial intracellular accumulation, is exported into the blood in amounts dependent on the severity of
the deficiency as well as coexistence of genetic factors or other
factors that may interfere with homocysteine metabolism.
Therefore, in the case of
hyperhomocysteinemia (high blood homocysteine levels) it can be useful to check if there is a deficiency of some of
these nutrients, which are essential to ensure a normal homocysteine
metabolism and to keep low homocysteine levels, preventing hyperhomocysteinemia.
Jean-Charles
Fruchart et al, Atherosclerosis:
Evolving Vascular Biology and Clinical Implications - New Risk
Factors for Atherosclerosis and Patient Risk Assessment. Circulation,
Cap. 109, 2004
Interventi
per ridurre l’omocisteina per la prevenzione degli eventi
cardiovascolari, www.omocisteina.net, 2013
EFSA Journal 2011
High Homocysteine Levels
May Double Risk of Dementia, Alzheimer’s Disease, New Report
Suggests
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