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When your body is healthy at a cellular level, you become even stronger. A food-based approach to increasing omega-3 consumption means regularly including items such as seafood—especially fatty fish—and many products enriched with long-chain omega-3s. We chose this trial as an example because of the very large number of subjects and because the reduction in risk approximates, but does not exceed, that reported for exercise and physical activity studies. It also includes arteries, veins, and capillaries. In this context, endurance-trained older subjects have baroreflex function that is similar to moderately active young subjects. Other classic studies include the work of Paffenbarger on Harvard alumni and Blair and colleagues on the interactions of cardiorespiratory fitness with obesity in terms of both cardiovascular and all-cause mortality Wei et al.
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You quickly deplete the 30 seconds' worth of fuel, a molecule called ATP, your muscles have on hand. Your muscles resort to glucose in your blood and a sugar, glycogen, stored in your muscles for raw material to make more ATP. Within a few minutes, your blood glucose levels start to dip, causing your pancreas to release a hormone, glucagon.
Delivered through your bloodstream to tissues throughout your body, glucagon triggers the release of glycogen stored in your liver and triglycerides, or fat, stored in fat cells under your skin and in your abdomen. As your muscles burn fuel to power movement, nerves in your arteries detect a rise in carbon dioxide, a waste product produced by energy metabolism. This triggers your brain to increase your heart and respiration rate.
Your lungs inhale more deeply to get oxygen needed for burning carbohydrates, and you exhale more strongly to expel the carbon dioxide. Meanwhile, your heart rate increases to deliver fuel and oxygen to your muscles and to transport carbon dioxide, lactic acid and other waste products away.
To handle the increased blood flow, your arteries, veins and capillaries dilate. When you do moderately intense cardio for 30 to 60 minutes a day at least three or four times a week, you give your lower body muscles a workout and you also improve your cardiovascular and respiratory fitness. You strengthen the cardiac muscle that surrounds your heart. The walls of your heart become thicker and stronger, and you pump a greater volume of blood with each stroke.
Consequently, your resting heart rate decreases. You develop more red blood cells, improving your ability to transport oxygen to your muscles. The capillaries that surround the alveoli in your lungs get wider and develop more branches, improving your capacity to exchange carbon dioxide and oxygen in your lungs. Improvements in circulation and oxygen delivery reduce the amount of lactic acid that accumulates during exercise. In particular, the quality of fat we eat, including the omega-3 fatty acids from fish, can reduce the impact of several of these factors.
Early observations on diet and vascular disease. Over two decades ago, investigators reported that deaths from coronary heart disease were more than 50 percent lower among people who consumed at least 30 grams of fish per day than among those who did not eat fish. Even before that, it was known that native Arctic populations, whose diet was rich in sea animals, were free of heart disease, thanks in part to the long-chain omega-3 fatty acids omega-3s they consumed.
Population studies and clinical trials indicated that dietary fish oils favorably modified various risk factors and had the potential to reduce vascular disease progression, the chance of dying from heart disease and the possibility of sudden cardiac death. In elderly individuals, eating tuna or other broiled or baked fish was associated with a lower chance of experiencing ischemic stroke.
Other studies found that the consumption of omega-3s reduced the chance of vascular disease, heart attack, inflammation, heart arrhythmias, sudden cardiac death, atherosclerosis and ischemic, but not hemorrhagic, stroke. In the secondary prevention of cardiovascular disease—that is, prevention following the occurrence of an initial coronary incident—studies have largely concluded that the consumption of fish or omega-3s significantly reduces the chance of another heart attack or major cardiac event.
The American Heart Association and many other professional groups have recommended the consumption of at least two fish meals a week to reduce the chance of heart disease. They note, too, that the plant-based omega-3 alpha-linolenic acid has only weak effects on heart disease and does not affect as many factors as the omega-3s in seafood.
The precise mechanisms for how omega-3s affect vascular disease are becoming better understood. Long-chain omega-3s are key components of cell membranes where they affect the communication within and between cells. By partially replacing their corresponding omega-6 counterparts in membranes, omega-3s can dampen the effect of omega-6s on inflammation and heart arrhythmias.
In vascular endothelial cells, omega-3s have numerous anti-inflammatory effects, especially at the sites where plaque accumulates. Omega-3 fatty acids affect all stages of vascular disease, including alterations in blood lipids and lipoproteins, blood pressure, platelet adhesiveness, relaxation of the arteries which eases blood flow and lowers blood pressure , changes in the electrical properties of the heart and alterations in gene expression.
Omega-3 fatty acids also reduce the growth of endothelial cells and the release of growth factors from injured blood vessels. These effects may help reduce the recurrence of narrowed blood vessels. Making healthy eating habits a way of life contributes beneficial nutrients and diminishes many conditions that promote vascular disease and other disorders.
Healthy food patterns, especially when accompanied by positive lifestyle habits such as exercising regularly and not smoking, can improve endothelial function, too. Improved nutrition has also been associated with less peripheral artery disease.
Eating patterns like those in the Mediterranean Figure 3 and the DASH diets minimize the intake of saturated and trans fatty acids, too much salt, and fried and heavily processed foods.
Instead, they emphasize eating generous amounts of fruits and vegetables, cereals rich in dietary fiber, fats such as olive and canola oils, herbs and spices instead of salt, nuts, moderate red wine, very little red meat, and eating fish and shellfish at least twice a week. In North America and elsewhere, current dietary intakes of omega-3s are well below those recommended by the American Heart Association and other health authorities. Intakes of to mg per day are considered more beneficial to health.
People with higher intakes of omega-3s have healthier endothelial function compared with those whose intakes are low. Thus, increasing omega-3 intake is likely to benefit vascular function, inflammatory processes and the diseases associated with these conditions. A food-based approach to increasing omega-3 consumption means regularly including items such as seafood—especially fatty fish—and many products enriched with long-chain omega-3s. These include eggs, yogurt, milk, spreads, some juices and beverages, and certain snack foods.
The caution is that foods claiming to have omega-3s may contain only the plant-based omega-3 alpha-linolenic acid. This omega-3 usually has only weak effects or none on many vascular and heart disease risk factors.
The only way to know which omega-3s are in a product is to read the food ingredient label.