SELENIUM and CARDIOVASCULAR DISEASE
Abstract: Selenium
appears to act as an antioxidant that reduces risk of cardiovascular diseases as
well as risk of cancer. An estimate from 8 studies found suggests risk of heart
disease and stroke may be reduced by about 40% by an added 100 mg per day of
dietary selenium. A usual amount in diet is about 90 mg. per day, but
benefits may accrue from amounts of selenium up to 200 mg per day. This
benefit is less well established than is that of Vitamin E. Selenium is
included in Life Ahead as one of four antioxidants that acts in combination with
each other but that in total has a limiting value. But because of its
potential benefit to heart disease, stroke, and cancer health-interested persons
should consider taking a 100 mg daily supplement of selenium.
Selenium has been extensively studied as an agent that might
reduce risk of cancer. Dozens of biochemical studies have indicated that this
mineral acts as an active antioxidant. Thus as expected it also reduces
risk of cardiovascular diseases. Results from eight studies found
relating the risk of cardiovascular diseases to selenium intake are shown in
Table S following. Selenium was measured as amounts in blood. Risk
ratios are for higher vs. lower amount use, and thus as usual in Life Ahead risk ratios below 1.00 identify
benefit for the mineral. Selenium in blood probably reflects fairly recent dietary
use, but we have no data from the research on how long selenium was used, and
dietary intake of selenium usually was not available in this research. Estimates of a possible
difference in dietary selenium are given in Table S from very limited
information relating Selenium in blood to that in diet
Some of the individual studies have
unusually high margins of error. For example study #1 has an error margin
of 1.58 that is well above the usual level of 1.00 considered as a maximum error
margin recognized as useful for inclusion of a result in Life Ahead. But
all other studies and especially those having lower error margins show
significant lowering of cardiovascular diseases for highest amounts of included
Selenium. Because of these error margins the conclusions cited in
abstracts of individual studies have been statistically confusing and
inconsistent.
A log-basis average of all results produces a risk ratio of about 0.60 with 5%
to 95% limits of about 0.41- 0.88. The data on stroke identify a very high
2/3rds benefit, but error margins on these studies are too high to accept this
level of benefit. This average result from all studies identifies
selenium as providing a 99% chance of benefit, a 90% chance of at least a 20%
reduction in risk, and a most probable 40% reduction of risk of cardiovascular
disease from the daily addition use of about 100 mg of selenium. No specific
information was found relating benefits of combinations of selenium with other
antioxidants. But further supporting importance of its probable health
value are results of many biochemical studies showing that Selenium is an
antioxidant that should slow the atherosclerosis that produces these
diseases. Also, populations with low selenium in local soils have been found to
experience higher death rates, and no really significant health negatives have been
established for its use at the levels considered in Life Ahead.
Life Ahead includes Selenium as
one of four antioxidants taken in sum as a group that benefit all cardiovascular
diseases. See the Antioxidant Model. In accord with the BioChemical
mechanism of atherosclerosis the benefits of antioxidants are taken as a
duration of exposure related risk, with a recognized limit of both maximum
benefit and duration of exposure. A usual US diet includes about 80-90 mg
of Selenium per day. Life Ahead credits a benefit for up to 100 mg of
supplemental use beyond that usual in diet. But this benefit accrues via
the antioxidant model only gradually over a 20 year period, and is usually
reduced further by presence of accompanying amounts of other antioxidants.
If substantial amounts of Vitamin E and other antioxidants are present in diet
and supplements, the addition of selenium may produce no added computed benefit
for cardiovascular diseases. The antioxidant model for heart disease
includes the benefits of selenium quite
conservatively.
But Selenium also appears to have
a substantial benefit by reducing risk of cancer. Thus the taking a
of a Selenium supplement of at least 100 mg per day would appear to be a prudent
action for any health-interested person.
Table S
Research on Selenium and Cardiovascular Disease
Study and
Reference Sex Risk Ratio, Error Margin Basis
Est Selenium
High vs. Low
5%-95% in Diets. mg/day
For Coronary Heart
Disease
1. Salvini,
S
Blood
Am J Cardiol
76:1218 M 1.27 0.71-2.29 Pop 5ths
40 & 140 100
2. Saudicani,
P.
Blood
Atherosclerosis
96:33 M 0.59 0.39-0.88 Pop 3rds
55 & 135 80
3. Beaglehole,
R
Blood
Int J Epidemiol
19:918 M 0.63 0.45-0.91 two groups
70 & 125 55
4.
Same W 0.59 0.29-1.11
same same
5. Kok, FJ
Blood
Am J Clin Nutr
45:462 M&W 0.91 0.38-2.0 Pop 5ths 40
& 140
100
For Stroke
6. Kok, FJ
Blood
Am J Clin Nutr
45:462 M & W 0.31 0.08-1.25 Pop 5ths 40
& 140 100
7. Virtamo,
J
Blood
Am J Epidemiol
122:276 M 0.27 0.08-1.0 Two groups 70
& 125
55
For All
Cardiovascular Disease
8. Kok, FJ
Blood
Am J Clin Nutr
45:462 M & W 0.63 0.31-1.25 Pop 5ths 40
& 140
100
T