homocysteine.net

The interest in homocysteine has burgeoned during the last few years. Homocysteine is now considered a risk factor for several diseases, particularly cardiovascular disease where elevated levels of the amino acid is associated with increased risk of morbidity and mortality.

The advent of simple assays has changed homocysteine measurement from a research tool to a standard and routine clinical test. The following sections will discuss the biochemical background as well as the association between elevated levels of Hcy and disease.

Site link: homocysteine.net

Vitamin B-12 status, particularly holotranscobalamin II and methylmalonic acid concentrations, and hyperhomocysteinemia in vegetarians

American Journal of Clinical Nutrition, Vol. 78, No. 1, 131-136, July 2003
© 2003 American Society for Clinical Nutrition

Wolfgang Herrmann, Heike Schorr, Rima Obeid and Jürgen Geisel

1 From the Central Laboratory, Department of Clinical Chemistry, Saarland University Hospital, Homburg, Germany.

Background
Vegetarians have a lower intake of vitamin B-12 than do omnivores. Early and reliable diagnosis of vitamin B-12 deficiency is very important.

Objective
The objective was to investigate vitamin B-12 status in vegetarians and nonvegetarians.

Design
The study cohort included 66 lactovegetarians or lactoovovegetarians (LV-LOV group), 29 vegans, and 79 omnivores. Total vitamin B-12, methylmalonic acid, holotranscobalamin II, and total homocysteine concentrations were assayed in serum.

Results
Of the 3 groups, the vegans had the lowest vitamin B-12 status. In subjects who did not consume vitamins, low holotranscobalamin II (< 35 pmol/L) was found in 11% of the omnivores, 77% of the LV-LOV group, and 92% of the vegans. Elevated methylmalonic acid (> 271 nmol/L) was found in 5% of the omnivores, 68% of the LV-LOV group, and 83% of the vegans. Hyperhomocysteinemia (> 12 µmol/L) was present in 16% of the omnivores, 38% of the LV-LOV group, and 67% of the vegans. The correlation between holotranscobalamin II and vitamin B-12 was weak in the low serum vitamin B-12 range (r = 0.403) and strong in the high serum vitamin B-12 range (r = 0.769). Holotranscobalamin II concentration was the main determinant of total homocysteine concentration in the vegetarians (ß = -0.237, P < 0.001). Vitamin B-12 deficiency led to hyperhomocysteinemia that was not probable in the upper folate range (> 42.0 nmol/L).

Conclusions
Vegan subjects and, to a lesser degree, subjects in the LV-LOV group had metabolic features indicating vitamin B-12 deficiency that led to a substantial increase in total homocysteine concentrations. Vitamin B-12 status should be monitored in vegetarians. Health aspects of vegetarianism should be considered in the light of possible damaging effects arising from vitamin B-12 deficiency and hyperhomocysteinemia.

Source: AJCN

To boost your ticker, cook steak quicker...

Realhealthnews Daily Dose - March 21, 2003

By now, you've probably heard about homocysteine. I've been
writing about it for nigh on 20 years, and unless you're new
to alternative medicine, you've probably heard a bit about
how it relates to heart disease...

But just in case you've haven't, here's a refresher:
Homocysteine is a harmful amino acid your body forms as a by-
product of the digestion of certain foods (like well-done
steak). Increased homocysteine in the bloodstream is
strongly associated with the occurrence of heart disease.
This correlation has been common knowledge in alternative
medicine circles for years.

Your body, however, has a built-in defense mechanism against
homocysteine buildup -- it transforms it into a harmless
substance called cystathionine, which is flushed from the
body in the urine. Again, old news.

Here's what's new: Recent research conducted in the
Netherlands points to the likelihood that some people are
genetically unable to convert homocysteine at a sufficient
rate, contributing to unsafe levels in the body and
subsequent increased risk of heart disease. This research
also studied the effects of a treatment for homocysteine my
alternative medicine colleagues and I have been recommending
for years: Folic acid. And the results confirmed what I've
known all along: Folic acid supplementation lowers
homocysteine, decreasing the risk of cardiovascular disease.

Now, other studies have shown this in the past. But the
Netherlands research took it one step further, concluding
that those people with a genetically reduced capacity to
process homocysteine were ONLY at increased risk for heart
disease when their folic acid levels were low...

What that means is this: Even if you're one of those
unfortunate souls whose body is ill-equipped to break down
homocysteine, folic acid supplementation can "even the
playing field" as far as your heart disease risk goes. But
taking folic acid isn't the only thing you can do to reduce
blood homocysteine -- Vitamins B12 and B6 are also critical
for the metabolism of this killer amino acid. Oh, and when
you cook steak, prepare it as rare as you can enjoy it --
because the closer to "well done" it is, the more
homocysteine you'll produce in digesting it...

But don't skip the steak altogether -- it's too good for
you! Just be sure to simply replenish your folic acid and B
vitamins regularly and you'll be fine.

Source: www.realhealthnews.com. Re-printed with permission.

Effect of protein and methionine intakes on plasma homocysteine

Effect of protein and methionine intakes on plasma homocysteine concentrations: a 6-mo randomized controlled trial in overweight subjects1,2,3

Nikolaj Haulrik, Søren Toubro, Jørn Dyerberg, Steen Stender, Annebeth R Skov and Arne Astrup

1 From the Research Department of Human Nutrition, The Royal Veterinary and Agricultural University, Copenhagen.

Background: A high plasma homocysteine concentration is an independent risk factor for cardiovascular disease. Homocysteine concentrations are thought to be raised by high protein and methionine intakes.

Objective: Our goal was to investigate the effects of high and low protein and methionine intakes on homocysteine in overweight subjects.

Design: Sixty-five overweight subjects were randomly assigned to a 6-mo intervention with a low-protein, low-methionine diet (LP: 12% of total energy, 1.4 g methionine/d; n = 25); a high-protein, high-methionine diet (HP: 22% of total energy, 2.7 g methionine/d; n = 25), both of which had similar fat contents (30% of total energy); or a control diet with an intermediate protein content (n = 15). All food was self-selected at a shop at the department. Protein intake was increased in the HP group mainly through lean meat and low-fat dairy products. Dietary compliance was evaluated by urinary nitrogen excretion.

Results: Homocysteine concentrations did not change significantly in the LP or control groups but were 25% lower in the HP group (NS). Homocysteine concentrations after the 3-mo intervention were inversely associated with vitamin B-12 intake and with weight change (by multivariate analysis performed for all subjects), but not with methionine or protein intake. Sixty-nine percent of the variation could be explained by baseline homocysteine (P < 0.001), 2% by vitamin B-12 (P = 0.02), and another 2% by weight change (P = 0.06). The plasma homocysteine concentration after 6 mo was associated only with baseline homocysteine (P < 0.001).

Conclusion: A high-protein, high-methionine diet does not raise homocysteine concentrations compared with a low-protein, low-methionine diet in overweight subjects.

Key Words: Protein • methionine • homocysteine • diet • obesity • cardiovascular disease

American Journal of Clinical Nutrition, Vol. 76, No. 6, 1202-1206, December 2002 © 2002 American Society for Clinical Nutrition

Source: http://www.ajcn.org/cgi/content/abstract/76/6/1202