Vegetable omega-3 and hypertension
Fatty acids and macular degeneration
Vitamin D and macular degeneration
Whole grains for heart and brain
Whole grains reduce inflammation
Flavonoids help brain function
Vitamin D and heart disease
Vitamin D from sun inadequate
Supplements of omega-3 essential fatty acids from fish lower blood pressure according to many studies. New research shows that consuming omega-3 oils from food sources, such as soybean oil, flaxseeds, and walnuts, has the same effect. (Ueshima H, et al., Food Omega-3 Fatty Acid Intake of Individuals (Total, Linolenic Acid, Long-Chain) and Their Blood Pressure. INTERMAP Study. Hypertension. 2007 Jun 4; [Epub ahead of print]
Plant sources of omega-3 oils contain alpha-linolenic acid (ALA), the precursor to EPA and DHA that are manufactured by the body. The study of 4680 subjects aged 40 to 59 showed modest decreases in both systolic and diastolic blood pressures with increasing consumption of ALA-containing foods.
You can maintain a normal blood pressure by following a vegetarian diet, reducing salt consumption, exercising regularly, and practicing stress reduction. Because each health habit contributes just a little to the benefit, it is important to combine the different health practices to achieve the greatest benefit. For strict vegetarians it is good to know that they can benefit from omega-3 without eating fish. However, with age and various health conditions, some people might not efficiently convert the ALA to EPA and DHA, and they would benefit from the fish oil sources.
Other research on omega-3 oils shows that a higher intake of fatty fish (including salmon) reduces the incidence of age-related macular degeneration (ARMD), a loss of vision in the most sensitive area of the retina.
In the study of 4519 participants 60 to 80 years old, those with the highest omega-3 consumption had a 40 percent reduction in ARMD compared to those with the lowest intake. (SanGiovanni JP, et al., The relationship of dietary lipid intake and age-related macular degeneration in a case-control study: AREDS Report No. 20. Arch Ophthalmol. 2007 May;125(5):671-9.)
The researchers also found that a high intake of arachidonic acid (AA, a non-essential fatty acid) led to a 54 percent increase in the risk of ARMD compared to the lowest AA intake. AA is found in land-animal fat, such as beef, dairy products, pork, lamb, chicken, and eggs. AA increases inflammation. It is not essential because your body makes all it needs from other omega-6 oil sources.
Another study of ARMD showed that vitamin D intake also plays a role in protection from that disease. In this research on 7752 subjects, the risk of developing the early stages of ARMD were reduced by 36 percent in those with the highest intake of vitamin D compared to those with the lowest intake. (Parekh N, et al., Association between vitamin D and age-related macular degeneration in the Third National Health and Nutrition Examination Survey, 1988 through 1994. Arch Ophthalmol. 2007 May;125(5):661-9.
The association was greatest for vitamin D intake from fish and supplements, while milk was in the middle. Of course, vitamin D is present in milk because it is added as a supplement, so the relationship is not directly with milk but with fish and supplemental sources. Vitamin D has anti-inflammatory effects and also inhibits excessive new vessel formation in the retina, both of which effects might contribute to its benefits in macular degeneration.
Two more studies confirm the value of whole grains in the diet for prevention of serious and lethal diseases. In one study of 1178 subjects averaging 55 years old, researchers evaluated the health of the carotid artery as measured by the thickness of the two innermost layers (the intima and media). This “intimal medial thickness” or IMT, is a measure of the presence and progression of atherosclerosis in the arteries supplying the brain. (Mellen PB, et al., Whole-grain intake and carotid artery athero-sclerosis in a multiethnic cohort: the Insulin Resistance Atherosclerosis Study. Am J Clin Nutr. 2007 Jun;85(6):1495-502.)
The IMT was evaluated using ultrasound studies at the start of the study and again five years later. In those who consumed the most whole grains, the IMT was lowest at the baseline and progressed the least over the five years. The analysis eliminated many other variables, including the overall health of the subjects’ dietary practices and lifestyles.
The analysis also controlled for separate components of the whole grains, including fiber, B vitamins, vitamin E, indicating that their value is from the combination of nutrients. Most Americans do not consume whole grains at all, although the demand is increasing. You certainly won’t find them at the local donut shop or burger emporium.
Whole grains also appear to help prevent other conditions unrelated to blood vessels or cancer. In the same journal as the report above, a study on 27,312 women from 55-69 years old followed for 17 years evaluated death rates from inflammatory conditions, such as asthma, rheumatoid disease, colitis, and lung disease. (Jacobs DR, et al., Whole-grain consumption is associated with a reduced risk of noncardiovascular, noncancer death attributed to inflammatory diseases in the Iowa Women's Health Study. Am J Clin Nutr. 2007 Jun;85(6):1606-14.)
Mortality from these conditions was cut in half in the group with the highest whole grain intake compared to that in the women who consumed the least whole grain. Inflammatory conditions are related to infections and immune disorders, and are frequently associated with oxidative stress resulting from the underlying diseases. Whole grains are rich in phyto-chemicals and antioxidants that reduce inflammation and oxidative stress. This report also confirmed at 17 years earlier reports in the same group that showed reduced mortality from heart disease and cancer with higher whole grain consumption.
It is possible that studies of whole grains have a flaw in that they are always comparing subjects who consume whole grains with those who eat refined grains (primarily white flour). It would be interesting to compare them with subjects who did not consume grains at all, but this is virtually impossible in cultures today where grains are a worldwide staple. The current evidence is that whole grains are very healthful, even if they were not a major component of pre-agriculture diets.
Flavonoids (or bioflavonoids) are plant-derived chemicals (phytochemicals) with important nutritional value, even though they are not essential to metabolism. A wide variety of flavonoids is found in fruits, vegetables, whole grains, and legumes.
New research shows that a high intake of flavonoids is associated with better brain function and a slower rate of cognitive decline with aging. A study in France of 1640 subjects over 65 years old showed that those with the highest flavonoid intake at the start of the study performed better on tests of mental function than those with the lowest intake. In addition, over the 10 years of the study, the functional decline of mental ability was significantly less in those with the highest intake.
The better brain function was not related specifically to fruits and vegetables or to red wine and tea, all sources of flavonoids, but to the overall flavonoid content of the diet. (Letenneur L, et al., Flavonoid intake and cognitive decline over a 10-year period. Am J Epidemiol. 2007 Jun 15;165(12):1364-71.) One improvement was in the Mini-Mental State examination, which showed twice as much decline in the group with the lowest flavonoid intake than in the group with the highest intake.
Although the subjects in this study did not take dietary supplements in significant quantities, many flavonoids are available as supplements. However, because of the wide variety of nutrients in fruits, vegetables, whole grains, and legumes, it is wise to consume these in large amounts in addition to any supplementation.
Several new studies show the importance of vitamin D for a variety of health problems unrelated to bones, for which its value is well known. In research on 15,088 men and women, low vitamin D levels were associated with a high prevalence of risk factors for heart disease. (Martins D, et al., Prevalence of cardiovascular risk factors and the serum levels of 25-hydroxyvitamin D in the United States: data from the Third National Health and Nutrition Examination Survey. Arch Intern Med. 2007 Jun 11;167(11):1159-65.)
In this research, subjects with the lowest vitamin D levels were the most likely to have diabetes, hypertension, and obesity compared to those with the highest levels. Hypertension was 30 percent more prevalent, diabetes was 98 percent higher, and obesity was more than double in the low vitamin D group.
The author noted to Reuters Health that while the currently recommended intake is 800-1200 IU daily, he thinks that 2000 IU is more likely to keep blood levels in a healthy range. He also said that 2000 to 3000 IU daily is well within the margin of safety.
Dietary supplements of natural vitamin D3 are important because the sun and general diet do not provide enough. In a study in Hawaii, where sun exposure is very high, researchers examined vitamin D levels in 93 people who spent over 28 hours a week in the sun (equivalent, according to the authors’ estimates, to 11 hours of full body exposure). Still, half of them had low vitamin D levels, even though their average age was 24 years old, and the study included men and women.
They recommend keeping blood levels of 25-OH vitamin D between 30 and 60 ng/ml (Binkley N, et al., Low vitamin D status despite abundant sun exposure. J Clin Endocrinol Metab. 2007 Jun;92(6):2130-5.) Levels lower than 30 were very common in this group, and it is likely that elderly people are even more at risk, as they manufacture vitamin D from the sun less efficiently than younger people.
Another study of Middle Eastern women showed that their vitamin D blood levels were low, probably due in part to their conservative dressing habits blocking sun exposure. (Saadi HF, et al., Efficacy of daily and monthly high-dose calciferol in vitamin D-deficient nulliparous and lactating women. Am J Clin Nutr. 2007 Jun;85(6):1565-71) Even supplementation with 2000 IU per day of synthetic vitamin D for three months was not enough to raise blood levels up to the recommended amount in 70 percent of the women. (Synthetic vitamin D was the only one available to these researchers.)
Supplements are present as additives in milk, but this is often synthetic vitamin D2 which is not as active as the natural D3. I have noticed recently that organic milk contains D3. However, capsules of natural D3 are a reliable and consistent daily source.
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