Dietary fiber and magnesium prevent hypertension
BOSTON, MASSACHUSETTS. Doctors at the Harvard School of Public Health
have completed a study to determine the relationship between diet and
hypertension (high blood pressure). The study involved over 30,000
male health professionals 40 to 75 years old. The baseline mean
systolic blood pressure for the men was 125.5 mm at age 40-44 and 133.7
mm at age 70-75. The diastolic blood pressure at 79.3 to 80.4 mm was
relatively unchanged with age. During four years of follow-up 1248 of
the men developed hypertension. An analysis showed that participants
consuming less than 250 mg per day of magnesium had a 50% greater
chance of developing hypertension than had men who consumed 400 mg/day
or more. Similarly, an intake of less than 2.4 g/day of potassium
increased the risk of hypertension by 50% as compared to an intake of
3.6 g/day or more. The most striking effect was found in the case of
dietary fiber where an intake of 24 grams/day or more was found to
provide significant protection. A higher intake of dietary fiber,
magnesium, and potassium was also found to be associated with lower
blood pressure in healthy men. The results of this study confirm the
findings of an earlier study involving 58,000 nurses. The authors
point out that although diet is important in preventing hypertension,
its effect is overshadowed by the risk imposed by obesity and excessive
alcohol intake.
Ascherio, Alberto, et al. A prospective study of nutritional factors
and hypertension among US men. Circulation, Vol. 86, No. 5, November
1992, pp. 1475-84
Vitamin C lowers blood pressure
AUGUSTA, GEORGIA. Researchers at the Medical College of Georgia have
confirmed that people with a high vitamin C concentration in their
blood have lower blood pressures than do people with little vitamin C.
They tested 168 healthy people, 56 of which were taking supplements
containing ascorbic acid. Among their findings: plasma ascorbic acid
levels were 11% higher in supplement users than in non-users; both
diastolic and systolic blood pressure were about 5 mm lower in people
having a high plasma level of vitamin C than in people having a low
level. Blood levels of selenium, vitamin A and vitamin E were not
found to affect blood pressure, but both obesity and smoking had a
significant adverse effect.
Moran, John P., et al. Plasma ascorbic acid concentrations relate
inversely to blood pressure in human subjects. American Journal of
Clinical Nutrition, Vol. 57, March 1993, pp. 213-17
Calcium combats high blood pressure
PORTLAND, OREGON. Researchers at the Oregon Health Sciences University
have just published a major overview on the current knowledge
concerning the effect of dietary minerals on high blood pressure. They
conclude that the effect of sodium intake on blood pressure is still
not clear. It may be that only a subset of people with a genetic
defect are sensitive to salt intake. The chloride ion in itself does
not seem to increase blood pressure, but when combined with sodium it
does cause hypertension in salt-sensitive individuals. A four-year
study of 60,000 nurses concluded that women who have a calcium intake
of 800 mg/day or more have a 23 per cent lower risk of developing high
blood pressure than women with an intake of 400 mg/day or less. The
benefits of calcium are even greater among pregnant women. Controlled
trials have found that women who consume between 1500 - 2000 mg/day of
calcium reduce their risk of developing pregnancy-induced hypertension
by as much as 50 per cent. It has also been shown that maternal
calcium intake directly affects the infant's blood pressure. Women
with a high calcium intake gave birth to babies with higher birth
weights and lower blood pressures. This lower pressure persisted
throughout at least the first five years of life. The effect of
potassium on blood pressure is still being actively investigated. One
trial found that a 50 per cent increase in potassium from natural foods
lowered blood pressure and dramatically reduced the need for blood
pressure-lowering drugs. Another trial found that supplementation with
potassium lowered blood pressure by 10 - 14 mm Hg. Several studies
suggest that a low magnesium intake is associated with hypertension,
stroke, and ischemic heart disease. It has been proposed that
supplementation with about 900 mg/day of magnesium, about 2.5 times the
RDA, is required in order to effectively lower blood pressure. (71
references)
Reusser, Molly E. and McCarron, David A. Micronutrient effects on
blood pressure regulation. Nutrition Reviews, Vol. 52, No. 11,
November 1994, pp. 367-75
Fish oils recommended for diabetes and hypertension
TROMSO, NORWAY. Fish and fish oils help protect against the
development of atherosclerosis and heart disease. It is believed that
fish oils exert their protective effect by lowering blood pressure and
the levels of triglycerides and very-low-density lipoprotein (VLDL).
Fish oils are also believed to reduce platelet aggregation and to
suppress the growth of smooth-muscle cells in the arterial walls. Many
people with hypertension also suffer from diabetes and there has been
concern that fish oil supplementation may aggrevate problems with
glucose intolerance. Researchers at the University of Tromso now
report that fish oil supplementation lowers blood pressure
significantly in people with hypertension and has no effect on glucose
control even in people with mild diabetes. The study involved 78 obese
volunteers with essential hypertension. The participants were randomly
assigned to one of two equal-sized groups. The fish oil group received
four fish oil capsules a day (containing a total of 3.4 grams of a
mixture of eicosapentaenoic acid and docosahexaenoic acid) for a period
of 16 weeks. The control group received four corn oil capsules a day.
At the end of the test period the average (mean) systolic blood
pressure had dropped by 4.4 mm Hg and the diastolic pressure by 3.2 mm
Hg in the fish oil group. The average blood pressure in the control
group did not change. The researchers also found that plasma
triglyceride and VLDL levels in the fish oil group decreased
significantly (by about 9 per cent) while they increased significantly
(by about 12 per cent) in the control group. There were no changes in
total or low-density-lipoprotein levels in either group. Extensive
tests (oral glucose tolerance, hyperglycemic and hyperinsulemic clamps)
were done to evaluate the effect of fish oil supplementation on glucose
control. No adverse effects were found. An editorial accompanying the
research report concludes that fish or fish oil is useful in the
prevention of vascular disease in diabetics. Patients with diabetes
should eat fish two to three times a week or, as an alternative,
supplement with two to three one gram capsules of fish oil per
day.
Toft, Ingrid, et al. Effects of n-3 polyunsaturated fatty acids on
glucose homeostasis and blood pressure in essential hypertension.
Annals of Internal Medicine, Vol. 123, No. 12, December 15, 1995, pp.
911-18
Connor, William E. Diabetes, fish oil, and vascular disease. Annals
of Internal Medicine, Vol. 123, No. 12, December 15, 1995, pp. 950-
52
Garlic lowers blood pressure and cholesterol
PROVIDENCE, RHODE ISLAND. Researchers at Brown University School of
Medicine report that supplementation with aged garlic extract lowers
cholesterol levels and blood pressure in men with high cholesterol
levels. Their experiment involved 41 men aged 32 to 68 years who had
total cholesterol concentrations between 5.7 and 7.5 mmol/L (220-290
mg/dL) at the start of the study. After a four-week baseline period
half the men were given nine aged garlic capsules (Wakunaga of America)
daily. Each capsule contained 800 mg of aged garlic extract. The
capsules were taken three at a time with meals for a six-month period.
The other half of the men were given a placebo. At the end of the six-
month period the supplementation was changed so that the former garlic
group was given the placebo and the placebo group was given the aged
garlic extract for an additional period of four months. Cholesterol
levels and blood pressure were measured monthly. The researchers
conclude that supplementation with aged garlic extract lowers total
cholesterol levels by an average of 6-7 per cent. Low-density-
lipoprotein cholesterol was lowered by an average of 4.6 per cent. The
researchers also noted a 5.5 per cent decrease in systolic blood
pressure and a smaller decrease in diastolic pressure. They found no
adverse effects of the garlic supplementation in regard to blood count,
blood chemistry, or thyroid function and conclude that garlic
supplementation for extended periods of time is safe and
beneficial.
Steiner, Manfred, et al. A double-blind crossover study in moderately
hypercholesterolemic men that compared the effect of aged garlic
extract and placebo administration on blood lipids. American Journal
of Clinical Nutrition, Vol. 64, December 1996, pp. 866-70
Potassium supplementation lowers blood pressure
BALTIMORE, MARYLAND. Researchers at the Johns Hopkins University
School of Medicine have come out in favour of using supplementation
with potassium in the treatment and prevention of hypertension (high
blood pressure). A group of seven medical researchers reviewed 33
randomized, controlled supplementation trials involving over 2600
participants. They conclude that potassium supplementation is
effective in lowering both systolic and diastolic blood pressure. The
average observed decrease in hypertensive patients was 4.4 mm Hg and
2.5 mm Hg for systolic and diastolic pressure respectively. In people
with normal blood pressure the observed decreases were 1.8 mm and 1.0
mm. The amount of elemental potassium used in the studies varied from
60 mmol (2.5 grams) to 120 mmol (5.0 grams) daily. Sixty mmol of
potassium is equivalent to 4.5 grams of potassium chloride, 6 grams of
potassium bicarbonate or 20 grams of potassium citrate. Oral potassium
supplementation appeared to be well tolerated in all the studies
examined. The researchers conclude that potassium supplementation
"should be considered as part of recommendations for prevention and
treatment of hypertension." Potassium supplementation is particularly
important in people who are unable to reduce their intake of
sodium.
Whelton, Paul K., et al. Effects of oral potassium on blood pressure.
Journal of the American Medical Association, Vol. 277, May 28, 1997,
pp. 1624-32
