The Risks of “Pre-hypertension”
It often seems as if treatment guidelines change every year. The levels at which experts recommend treating cholesterol, glucose levels and blood pressure have all changed recently. Some cynics say that it’s all a device by drug companies to get more people on treatment, but that’s not really true. The guidelines change as we get more evidence that not treating something leads to bad consequences in the future. A good example would be the level at which experts recommend treating elevated blood glucose. The recommendation was changed when it was discovered that even small elevations of glucose could have a dramatic impact on the development of coronary artery disease.
We now have another change, this time with blood pressure. Everyone knows that high blood pressure can be dangerous. But researchers have recently defined something that we call pre-hypertension (a systolic blood pressure 120 to 139 mm Hg or diastolic blood pressure 80 to 89 mm Hg). What was not known for sure was what impact pre-hypertension would have on the incidence of cardiovascular disease.
A study published in the journal Hypertension has clarified the issue. The research involved 2629 people participating in the twelve-year-long Strong Heart Study. Pre-hypertension was more common in people with diabetes. And as expected, from the link between blood pressure and insulin resistance, impaired glucose tolerance or impaired fasting glucose in pre-hypertensive people greatly increased the risk of developing cardiovascular disease risk. We now need to do more research to see if interventions, such as drug treatment for blood pressure control for pre-hypertensive individuals are warranted. This is particularly important if people also have impaired fasting glucose, impaired glucose tolerance, or diabetes is warranted, because risk factors for coronary artery disease are cumulative: the more risk factors, the bigger the risk.
What this means is that your health care provider should help you keep your blood pressure lower than we thought, particularly if you have a personal or a family history of problems with blood glucose or of heart disease.
Technorati tags:Hypertension Insulin resistance Diabetes mellitus Coronary artery disease
Insulin Resistance, Insulin Resistance Syndrome and Race
I often hear clinicians say that they are not too clear about the differences between insulin resistance and insulin resistance syndrome. Let me define them, and then tell you why they are so important, and why everyone needs to be informed about them.
First, insulin is a hormone produced primarily in the cells of the Islets of Langerhans in the pancreas. It has over 500 functions in the human body, but its main actions are on the regulation of the metabolism of carbohydrates and fats. Insulin enables glucose – one of the major sources of energy – to move into many of the cells in the body. Insulin is also involved in the conversion of glucose to glycogen. These two actions lower the blood glucose level.
Insulin resistance is defined as an impaired biological response to insulin. It is a condition in which many of the cells of the body – mainly in the liver, fat and muscle – become resistant to the effects of insulin. The normal responses to a given amount of insulin are reduced. As a result, higher levels of insulin are needed in order for insulin to have its effects. There are many potential causes of insulin resistance: genetic; an increase in intra-abdominal fat; smoking cigarettes; being of low birth weight; and there are some prescription medicines that can cause insulin resistance. Insulin resistance is one of the underlying causes of type 2 (maturity onset) diabetes mellitus, as well as an array of other illnesses including polycystic ovarian syndrome. Most studies have suggested that around a third of people living in the United States and Western Europe have insulin resistance, and there are marked ethnic differences.
The insulin resistance syndrome has several other names: Metabolic syndrome; (Metabolic) Syndrome X; Dysmetabolic syndrome; Reaven’s syndrome; multiple metabolic syndrome. There are several sets of criteria for defining the insulin resistance syndrome. In the USA it is usually defined as the presence of 3 or more of the following:
1. Abdominal obesity (Waist circumference >40 inches in men; >35 inches in women
2. Glucose intolerance (fasting glucose ≥110 mg/dL)
3. Elevated blood pressure ≥130/85 mmHg
4. Triglycerides >150 mg/dL
5. Low HDL (Men: <40 mg/dL; women: <50 mg/dL)
There is a constant debate in the medical literature about whether insulin resistance syndrome is an illness, and what should be included in it. It is important, because it appears to predict the development of diabetes and coronary artery disease, and between 20 and 25% of the population of the Western world has it. So what normally happens is that a person develops insulin resistance, which eventually evolves into the insulin resistance syndrome, before diabetes and heart disease appears. There can be as long as twelve years between the development of insulin resistance, and the diagnosis of diabetes, and we have very good evidence that lifestyle changes can dramatically reduce the risk of moving from insulin resistance to the insulin resistance syndrome and diabetes.
It has become quite well-known that people of African and Asian Indian heritage are at increased risk of developing insulin resistance, and some of the sequelae of insulin resistance: insulin resistance syndrome, diabetes mellitus, hypertension and gout. These may in turn lead to increased rates of myocardial infarction and strokes. A study presented last Monday at ENDO 2006, the annual meeting of the Endocrine Society in Boston helps further clarify some of these ethnic differences. Researchers analyzed data from the Insulin Resistance Atherosclerosis Study (IRAS), designed to assess relationships between insulin resistance and cardiovascular disease in a large multi-ethnic population.
The investigators divided data from female IRAS participants into different groups based on body mass index (BMI), a measure of body fat based on height and weight. A BMI of less than 25 is usually considered "normal." The analysis revealed that 47 percent of black women of normal weight had insulin resistance, compared to less than 20 percent of the Hispanic or White women. Both insulin resistance and the likelihood of developing type 2 diabetes increase as obesity increases. It had long been suspected that there was an independent effect of race, but this study not only shows that race alone may influence insulin resistance, but that we may therefore need to change the definition of obesity in women of African heritage.
The news reports on this important finding failed to mention that previous research has found something very similar in Asians from India, China and Japan. Each of these ethnic groups may develop insulin resistance, insulin resistance syndrome and diabetes without being obese, though obesity dramatically increases their risks of running into trouble.
It is relatively simple and inexpensive to measure insulin resistance, and many metabolic experts, including your humble reporter, have, for more than a decade, been measuring it in high-risk individuals. Clearly we cannot do anything much about an ethnic or genetic risk, but we can alter the way in which the body responds to that risk. If a person is insulin resistant, diet, exercise, specific nutritional and herbal interventions and occasionally medications, may all reduce the risk of developing diabetes and heart disease.
Technorati tags:Insulin Insulin resistance Insulin resistance syndrome Metabolic syndrome Diabetes mellitus Obesity Hypertension Racial differences
Integrated Health and Aging
An important principle of the emerging laws of health and healing is that anything helpful should help more than one system of the body at a time. So a diet that might help mitigate the effects of aging in the skin should also have beneficial effects on the major organs of the body.
So I was encouraged to see a new report indicating that cardiovascular health and a healthy lifestyle are associated with maintaining the health of our brains as we age. This is, of course, intuitively obvious, but it is always nice to see such things confirmed by empirical research.
The new report is from a multi-Institute collaboration of the National Institutes of Health (NIH) published online in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association. The chair of the committee was Hugh Hendrie, the Scottish-born professor of psychiatry from the University of Indiana, and the committee members were many of the most eminent people in the fields of aging and Alzheimer’s disease.
What is encouraging about this new report is that many of the factors associated with cognitive decline as we get older are eminently remediable: we have within our reach a set of potential interventions that could significantly reduce our personal risk of developing cognitive problems later in life. These are the things that we need to work on if we want to reduce our risk of developing cognitive decline later in life:
- Hypertension: There is excellent evidence that inadequately treated hypertension correlates strongly with cognitive decline.
- Physical activity: There is good evidence that elders who exercise regularly are less likely to experience cognitive decline. This is over and above the general improvement in quality of life that accompanies regular exercise. The earlier in life that we start, the easier it is to continue.
- Increased mental activity throughout life, including learning new things and going through higher education may benefit the health of the brain.
- Moderate alcohol use and the use of vitamin supplements also seem to be brain protectors, though the report does not specify which supplements.
- Social disengagement and depressed mood are both associated with poorer cognitive functioning, so it is important to be alert to signs of depression, and to maintain a social network. I discuss this in more detail in my book Healing Meaning and Purpose.
There are doubtless some genetic and environmental factors about which we can do little. But the idea that we now have a list of things that we can do to protect our brains is very exciting.
This report also signals another important change. In recent years we have seen the growth of Positive Psychology, the study of how to improve ourselves rather than the constant focus on psychopathology. This report calls for the research community to study health maintenance of the brain with the same energy that it has brought to bear on the study of diseases of the brain. To which I would add, that we must not just focus on how to maintain the health of the brain, but how we can enhance it’s function so that we can all reach and exceed our full potential.
Technorati tags: aging, Integrated health, Positive Psychology, healthy lifestyle,
Lectins, Leptin and the China Study
I have just reviewed a most interesting book called The China Study at Amazon.
This book, touted as the most comprehensive study of nutrition ever conducted, is indeed a treasure trove of useful information. The first point that I particularly liked is that the author is not a reductionist. He understands that the idea of trying to reduce the value of foods to one food type or one nutrient is deeply flawed. Let me give you an example: there is some good evidence that tomato-derived lycopene has a great many health benefits, but that does not mean that the solution to all that ails us is a diet consisting solely of tomatoes. I was once asked to see a person who had a genuine problem with a series of food sensitivities: a well-meaning but poorly educated practitioner had put her on a diet of lettuce leaves, rice and spring water. Several months later I saw her because of profound weight loss and malnutrition. The problem was a lack of balance in the dietary approach, and failing to see the big picture.
T. Colin Campbell is definitely one who sees the big picture, both in terms of his own research, and the broader context. He rightly points out that trying to divorce nutrition from the whole diet and lifestyle is a fundamental mistake.
I noticed something rather interesting, which I have just seen picked up by another reviewer: there seems to be a strongly positive correlation between wheat consumption and the risk of sustaining a myocardial infarction.
The reason that I perked up on seeing this is that I have just been analyzing a paper from Lund in Sweden. The investigators’ fundamental premise is that the rise of agriculture and the consumption of cereals might be the underlying explanation for many of the diseases of affluence. The researchers did a study of pigs, and showed that by putting them on a cereal-free diet, the pigs’ insulin resistance, blood pressure and C-reactive protein all fell, which are excellent markers of cardiovascular health. They went even further and provided a biochemical explanation, pointing out that for all its many benefits, agriculture is exposing our bodies to novel lectins: plant proteins that bind to specific carbohydrate groups on cell membranes. (We met lectins in my previous posting on blood types). These lectins seem to have the worst type of biochemical properties that enable them to block the action of a key metabolic hormone called leptin. First discovered in 1994, leptin produces a satiety signal, telling your brain to stop eating. In some animals it may also cause insulin resistance. Leptin was very hot news a few years ago, because if an animal or a person is resistant to leptin, they become morbidly obese. So a number of pharmaceutical companies tried to develop obesity treatments based on leptin. Sadly, to date all of them have failed. It is not surprising that nutritional interventions based on modulating leptin have also been disappointing. At last count there were over 260 hormones and neurotransmitters involved in the maintenance of body-weight. So trying to manipulate just one of them is hardly likely to be crowned with success.
As I have said in other posts, there will always be someone, somewhere, who will respond to any kind of eating or life plan. The trick is in predicting who will respond to what, and in that we are still scratching our heads. So if you want an approach that has the highest overall chance of success at maintaining and improving your health, rather than just focusing on pounds, I’m going to repeat my advice from an earlier posting:
1. It is important for you to maintain your energy balance, between input and output
2. Calories do count
3. What you include in your diet is as important as what you exclude: we are designed to consume not just rice and lettuce, but an array of other nutrients.
4. Make only moderate dietary changes at any time: making big dietary changes can be a pretty violent attack on your body and your mind
5. Avoid the “trans-fatty acids”
6. Try to consume some omega-3 fatty acids every single day
7. Eat fewer simple carbohydrates
8. Use weight management and exercise strategies that enhance your overall health and well-being
9. Take more exercise: even small amounts can have a big effect.
And now I am going to add a tentative number 10:
10. If your weight and metabolic parameters are still not as they should be, discuss a gradual reduction of cereal intake with your health care provider, and how to ensure that you still get the amount of fiber that you need. Depending upon your own genetic make-up that may be the missing piece.
Technorati tags: The China Study, T. Colin Campbell, diet, lifestyle change, nutrition
