Posted by Larry Hoover on April 21, 2003, at 8:03:43
In reply to Re:Flax SEEDS-how much for depression (q to Larry), posted by btnd on April 21, 2003, at 2:15:43
> Thanks Paul!
> Now, I just need someone knowledgeable on the scientific subject of flax seeds (using omega3 fatty acids for depression). So here is my q to Larry:So, automatically I'm an expert on flaxseeds? <teasing>
>if Paul's calculations are correct, then what would be the working dosage of flax seeds? and how many times a day should I take it? I have dysthymia. Thanks in advance.
Here's a good source for background information on flax. They may be selective (it's a flax marketing association website), but I don't see any distortion in their information.http://www.flaxcouncil.ca/flaxnutT.htm
I had to find a conversion factor for flaxseed volume/mass to ALA content. I found that one tablespoon provides 2.8 grams of ALA. The only other key relationship is: How much EPA is formed from the ALA in the flax oil? Well, that depends on your gender. Females do much better than males. In fact, the first abstract (below) recommends that males obtain their DHA from their diet, preformed, as so little is synthesized from ALA.
So, let's say you're female, and you want to get your EPA intake (or equivalent) up around the 1 gram per day mark. If you're converting 20%, you'd need 5 grams of ALA, or roughly two tablespoons flaxseed per day. However, if your linoleic acid (very common in vegetable oils) intake is relatively high, conversion is suppressed by 40%, so you'd need more like 4 tablespoons flax per day.
If you're male (6% conversion), you'd need 6 tablespoons (10 tablespoons with high vegetable oil intake).
These figures are based on averages. Your body will likely vary from these estimates. 10 tablespoons per day of flax would likely have an adverse effect on your sex hormones (lignan binds sex hormones). Now, if you're female and suffer from PMS, you might want to bind your sex hormones. <shrug>
If you added 2 tablespoons/day ground flax seed to your diet, I think you determine whether or not it's of any benefit to you. Ground flax has a mild nutty taste, and can be spooned over breakfast cereal, added to a smoothie, sprinkled into a sandwich, whatever your imagination suggests to you.
From the first abstract:
"Since the capacity of adult males to convert ALNA to DHA was either very
low or absent, uptake of pre-formed DHA from the diet may be critical for
maintaining adequate membrane DHA concentrations in these individuals."
Br J Nutr 2002 Oct;88(4):355-64Eicosapentaenoic and docosapentaenoic acids are the principal products of
alpha-linolenic acid metabolism in young men*.Burdge GC, Jones AE, Wootton SA.
Institute of Human Nutrition, Level C, West Wing, Southampton General
Hospital, Tremona Road, Southampton, SO16 6YD, UK.The capacity for conversion of alpha-linolenic acid (ALNA) to n-3 long-chain
polyunsaturated fatty acids was investigated in young men. Emulsified
[U-13C]ALNA was administered orally with a mixed meal to six subjects
consuming their habitual diet. Approximately 33 % of administered [13C]ALNA
was recovered as 13CO2 on breath over the first 24 h. [13C]ALNA was
mobilised from enterocytes primarily as chylomicron triacylglycerol (TAG),
while [13C]ALNA incorporation into plasma phosphatidylcholine (PC) occurred
later, probably by the liver. The time scale of conversion of [13C]ALNA to
eicosapentaenoic acid (EPA) and docosapentaenoic acid (DPA) suggested that
the liver was the principal site of ALNA desaturation and elongation,
although there was some indication of EPA and DPA synthesis by enterocytes.
[13C]EPA and [13C]DPA concentrations were greater in plasma PC than TAG, and
were present in the circulation for up to 7 and 14 d, respectively. There
was no apparent 13C enrichment of docosahexaenoic acid (DHA) in plasma PC,
TAG or non-esterified fatty acids at any time point measured up to 21 d.
This pattern of 13C n-3 fatty acid labelling suggests inhibition or
restriction of DHA synthesis downstream of DPA. [13C]ALNA, [13C]EPA and
[13C]DPA were incorporated into erythrocyte PC, but not
phosphatidylethanolamine, suggesting uptake of intact plasma PC molecules
from lipoproteins into erythrocyte membranes. Since the capacity of adult
males to convert ALNA to DHA was either very low or absent, uptake of
pre-formed DHA from the diet may be critical for maintaining adequate
membrane DHA concentrations in these individuals.Br J Nutr 2002 Oct;88(4):411-421
Conversion of alpha-linolenic acid to eicosapentaenoic, docosapentaenoic and
docosahexaenoic acids in young women.Burdge GC, Wootton SA.
Institute of Human Nutrition, University of Southampton, Southampton, UK.
The extent to which women of reproductive age are able to convert the n-3
fatty acid alpha-linolenic acid (ALNA) to eicosapentaenoic acid (EPA),
docosapentaenoic acid (DPA) and docosahexaenoic acid (DHA) was investigated
in vivo by measuring the concentrations of labelled fatty acids in plasma
for 21 d following the ingestion of [U-13C]ALNA (700 mg). [13C]ALNA
excursion was greatest in cholesteryl ester (CE) (224 (sem 70) &mgr;mol/l
over 21 d) compared with triacylglycerol (9-fold), non-esterified fatty
acids (37-fold) and phosphatidylcholine (PC, 7-fold). EPA excursion was
similar in both PC (42 (sem 8) &mgr;mol/l) and CE (42 (sem 9) &mgr;mol/l)
over 21 d. In contrast both [13C]DPA and [13C]DHA were detected
predominately in PC (18 (sem 4) and 27 (sem 7) &mgr;mol/l over 21 d,
respectively). Estimated net fractional ALNA inter-conversion was EPA 21 %,
DPA 6 % and DHA 9 %. Approximately 22 % of administered [13C]ALNA was
recovered as 13CO2 on breath over the first 24 h of the study. These results
suggest differential partitioning of ALNA, EPA and DHA between plasma lipid
classes, which may facilitate targeting of individual n-3 fatty acids to
specific tissues. Comparison with previous studies suggests that women may
possess a greater capacity for ALNA conversion than men. Such metabolic
capacity may be important for meeting the demands of the fetus and neonate
for DHA during pregnancy and lactation. Differences in DHA status between
women both in the non-pregnant state and in pregnancy may reflect variations
in metabolic capacity for DHA synthesis.Int J Vitam Nutr Res 1998;68(3):159-73
Can adults adequately convert alpha-linolenic acid (18:3n-3) to
eicosapentaenoic acid (20:5n-3) and docosahexaenoic acid (22:6n-3)?Gerster H.
Vitamin Research Department, F. Hoffman-Roche Ltd, Basel, Switzerland.
A diet including 2-3 portions of fatty fish per week, which corresponds to
the intake of 1.25 g EPA (20:5n-3) + DHA (22:6n-3) per day, has been
officially recommended on the basis of epidemiological findings showing a
beneficial role of these n-3 long-chain PUFA in the prevention of
cardiovascular and inflammatory diseases. The parent fatty acid ALA
(18:3n-3), found in vegetable oils such as flaxseed or rapeseed oil, is used
by the human organism partly as a source of energy, partly as a precursor of
the metabolites, but the degree of conversion appears to be unreliable and
restricted. More specifically, most studies in humans have shown that
whereas a certain, though restricted, conversion of high doses of ALA to EPA
occurs, conversion to DHA is severely restricted. The use of ALA labelled
with radioisotopes suggested that with a background diet high in saturated
fat conversion to long-chain metabolites is approximately 6% for EPA and
3.8% for DHA. With a diet rich in n-6 PUFA, conversion is reduced by 40 to
50%. It is thus reasonable to observe an n-6/n-3 PUFA ratio not exceeding
4-6. Restricted conversion to DHA may be critical since evidence has been
increasing that this long-chain metabolite has an autonomous function, e.g.
in the brain, retina and spermatozoa where it is the most prominent fatty
acid. In neonates deficiency is associated with visual impairment,
abnormalities in the electroretinogram and delayed cognitive development. In
adults the potential role of DHA in neurological function still needs to be
investigated in depth. Regarding cardiovascular risk factors DHA has been
shown to reduce triglyceride concentrations. These findings indicate that
future attention will have to focus on the adequate provision of DHA which
can reliably be achieved only with the supply of the preformed long-chain
metabolite.
poster:Larry Hoover
thread:220804
URL: http://www.dr-bob.org/babble/20030417/msgs/221096.html