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How does obesity increase the risk of cardiovascular disease? How does obesity increase the risk of cardiovascular disease? The risk of death from CVD is two to three times higher in obese people (BMI ≥ 30) than in those with a healthy body weight. Body mass index (BMI) at age 18 predicts mortality due to CVD; the higher your BMI at age 18, the more likely you are to eventually die from CVD. Maintaining a healthy weight is also important: For example, a study of middle-aged women found that those who had gained 22 or more pounds since age 18 had a significantly higher risk of subsequent death from CVD than those who were able to maintain their weight over time. The increased risk of CVD associated with overweight is present even if a person has no other risk factors but, unfortunately, overweight people usually have other CVD risk factors. Excess body fat is strongly associated with hypertension, high cholesterol levels, insulin resistance, diabetes, physical inactivity, and increasing age. It is also associated with endothelial cell dysfunction and increased markers of inflammation. Endothelial cells line the inside of arteries, including the coronary arteries, and they help regulate blood flow to the heart and keep platelets and other cells from sticking to artery walls. When the endothelial cells are healthy, the coronary arteries dilate (widen) when the heart needs more blood, but when the cells are dysfunctional, the coronary arteries instead constrict, limiting blood flow to the heart. With excess weight, there is also more blood to pump and the heart has to work harder. This causes chronically elevated pressures within the heart chambers that can lead to enlargement of the ventricles, and eventually the heart muscle can start to fail. A sensible diet and regular physical activity can help people achieve and maintain a healthy body weight. Physical activity improves cardiovascular health even in those who are overweight and obese. How does stress contribute to cardiovascular disease? With stress, the brain tells the adrenal glands to secrete specialized hormones and neurotransmitters, which in turn activate the sympathetic nervous system—causing the fight-or-flight response. This response increases heart rate and blood pressure so that more blood is distributed to the heart and other muscles in anticipation of physical activity. Blood glucose concentrations and cholesterol also increase to provide a source of energy, and the platelets become activated so that they will be more likely to clot in case of injury. Such a response can be adaptive if you're being chased by a hungry lion but may be more detrimental than useful if you're sitting at a desk taking an exam or feeling frustrated by a task given to you by your work supervisor. If you are healthy, you can tolerate the cardiovascular responses that take place during stress, but if you already have CVD, stress can lead to adverse outcomes such as abnormal heart rhythms, heart attacks, and sudden cardiac death. It has long been known that an increase in heart rhythm problems and deaths is associated with acute mental stress. For example, the rate of potentially life-threatening arrhythmias in patients who already had underlying heart disease doubled during the month after the September 11 terrorist attacks; and this increase was not limited to people in close proximity to Manhattan. Because avoiding all stress is impossible, having healthy mechanisms to cope with it is your best defense. Instead of adopting unhealthy habits such as smoking, drinking, or overeating to deal with stress, try healthier coping techniques such as exercising, getting enough sleep, and talking to family and friends. Metabolic syndrome, also know as insulin resistance syndrome or syndrome X, is a group of abnormalities that often occurs together and that increase the risk of CVD. The syndrome usually has its basis in problems with insulin and glucose regulation. When you consume carbohydrate, your blood glucose level rises. This stimulates the pancreas to secrete insulin, which allows body cells to pick up glucose to use for energy. The function of insulin is to maintain proper glucose levels in the body, which it does by affecting the uptake of glucose from the blood by muscle and fat tissue and by limiting the liver's production of glucose. As people gain weight and engage in less physical activity, their muscles, fat, and liver become less sensitive to the effect of insulin—a condition known as insulin resistance, or pre-diabetes. As the body becomes increasingly insulin resistant, the pancreas must secrete more and more insulin to keep glucose within a normal range. Eventually, however, even high levels of insulin may become insufficient, and blood glucose levels will also start to rise, resulting in type 2 diabetes. Those who have insulin resistance tend to have several other related risk factors; as a group, this cluster of abnormalities is called metabolic syndrome. The defining characteristics are listed below:
Having metabolic syndrome significantly increases the risk of CVD—up to three times in men and six times in women. Some people are genetically predisposed, and among this group, factors such as excess body fat and inactivity can elicit insulin resistance. However, metabolic syndrome is not limited to obese people. Strategies for reducing the risk of metabolic syndrome including regular physical activity, weight loss (if needed), and limiting intake of added sugars, starches, and high-glycemic index foods. Is it true that heart attacks are more likely at certain times of the day or year? Yes. More heart attacks and sudden cardiac deaths occur in the morning hours between 6:00 AM and noon than during other times of the day. This trend may be due to the natural increase in adrenaline and cortisol levels that occurs in the morning and by an increase in the sympathetic nervous system activity as people hurry around at the beginning of the day. Blood pressure is often lowest during sleep and highest in the morning, and endothelial function may be impaired in the early morning. There is also a seasonal pattern of heart attacks, with up to 50% more occurring in the winter months than in summer months. Heart attacks that occur in winter also tend to be more often fatal than those that occur during summer. Possible explanations include low temperature, which can constrict blood vessels; bursts of exertion, such as snow shoveling; increased rates of smoking; increased stress and depression, including seasonal affective disorder (depression linked to reduced daylight hours during winter); holiday-related episodes of high-fat eating and binge drinking; and physiological factors including cholesterol levels, which appear to rise in winter. People who have symptoms of heart trouble may also be more reluctant to seek help during the holidays. Is it possible to get atherosclerosis in arteries in the legs and arms? Yes. People are most familiar with the dangers of atherosclerosis in the arteries of the heart and brain, where the condition can cause heart attacks and strokes. But atherosclerosis can also occur in arteries in the legs or arms, a condition known as peripheral arterial disease (PAD). As with atherosclerosis in the heart or brain, the condition can progress so that blood flow through the artery is limited or completely blocked. About 10 million Americans have PAD. The risk factors associated with coronary atherosclerosis, such as smoking, diabetes, hypertension, and high cholesterol, also contribute to atherosclerosis in the peripheral circulation. Symptoms of PAD include claudication and rest pain. Claudication is aching or fatigue in the affected limb that occurs with exertion, particularly walking, but resolves with rest. Claudication occurs when leg muscles do not get adequate blood and oxygen supply. Rest pain occurs when the limb artery is unable to supply adequate blood and oxygen even when the body is not physically active. This occurs when the artery is significantly narrowed or completely blocked. If blood flow is not restored quickly, cells and tissues may become infected and die. In severe cases, amputation may be needed. PAD is the leading cause of amputation in people over age 50. Why is salt (sodium) so bad for you? For years, medical experts have warned Americans that too much sodium (a main component of table salt and an ingredient in many kinds of food) can be bad for your health. Most Americans, however, don't know why this is true. Sodium is actually an important mineral that is essential to certain body functions. One of sodium's most important roles is in helping the body regulate the balance of fluid within cells and blood. But the body needs only about one-half a gram (less than one-quarter of a teaspoon) of sodium per day for this purpose. Most Americans, however, consume many times more sodium than they need every day. By contrast, the American Heart Association recommends consuming no more than 2.3 grams (about 1 teaspoon) of salt each day. When there is too much sodium present, the body begins to retain water instead of expelling it. Excess water increases the volume of blood, so the heart and blood vessels must work harder to move the blood through the body. The extra workload strains the circulatory system, leading to problems such as high blood pressure, enlargement of the heart, and swelling in various parts of the body. If these problems persist, they can lead to permanent damage and ultimately death. An easy way to reduce the risk of cardiovascular disease is to reduce your intake of sodium in the foods you eat. Here are some tips that can help:
Is there a simple way to tell if someone is having a stroke? Only a trained professional can tell for sure whether someone is suffering a stroke, but everyone should learn to recognize the warning signs. When someone has a stroke, every second counts. The sooner a stroke victim receives medical attention, the better his or her chances of surviving without long-term damage to the brain. Stroke symptoms occur suddenly, with no warning. Symptoms can include the following:
If you think someone is having a stroke, call 9-1-1 immediately and ask for medical help. While waiting for help to arrive, ask the victim to do three simple tasks. The person's ability to respond may help you determine whether the problem is a stroke.
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