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Tuesday, March 6, 2012

Book Review: The End of illness by David Agus, MD

The recently published book, “The End of Illness” by David Agus, MD has received considerable positive attention. Its author is a professor of medicine and engineering at the University of Southern California medical school and the school of engineering. He heads USC’s Westside Cancer Center and the Center for Applied Molecular Medicine, and cofounded two companies that are attempting to personalize medicine: Navigenics, which seeks to identify an individual’s predisposition to various diseases from genetic testing, and Applied Proteomics, which intents to get even more health information from quantification of an individual’s proteins. He chairs the Global Agenda Council on Genetics for the World Economic Forum, and has received several awards including the 2009 GQ Magazine Rock Star of Science award.

I must say at the outset that the book is somewhat of a disappointment. It’s virtually impossible for a book to live up to such an audacious title and I hope it was the publishers who titled it rather than the author. In reality, the book offers little hope for an end to illness. Rather, it mainly offers a peek into a future in which, through genetic and protein testing, a patient can be well informed about his/her predisposition to various diseases and responsiveness to drug therapies. But the value of such knowledge seems to be overstated. Agus postulates that, knowing one’s tendency towards obesity will motivate someone to eat better and exercise more. However, all of us should be trying to do so. It is best to do all we can to maintain and improve our health, rather than merely targeting our greatest weaknesses. Also, many people know what their vulnerabilities are, from overeating to smoking to inactivity to drug abuse, but such knowledge most often fails to correct such adverse behavior. Thus, the book’s praise of what the author’s companies do comes across as both self-aggrandizement and advertising of services or investment opportunities.

Despite the weaknesses in the book, it offers some good basic health advice, most of which has been widely reported in other books and articles on health. Some of the book’s major points {with the book's recommendations in bold and my comments in brackets}:

We may never understand illnesses such as cancer. In fact, we may never cure cancer, which is why prevention is key. {This obvious point contradicts the book title’s hype. While preventive measures can reduce the risk of cancer, and possibly delay its onset to more advanced ages, there is no indication of anything on the horizon that can prevent cancer. In fact, as we continue to improve treatment of heart disease and infectious disease, a greater percentage of people are likely to live long enough to die of cancer.}

Everyone should ask for the following tests at their checkup. {The first three are typically done. The C-reactive protein is usually done for those with risk factors for heart disease. The PSA test is often done but is controversial because of its poor ability to determine who really needs further, more invasive, procedures. The test for thyroid stimulating hormone is not typically done except if there are symptoms suggesting a need for it. The hemoglobin A1C is not typically done but is a better test of long-term blood sugar than the standard blood glucose test as an indicator of diabetes risk.}:
·         Fasting lipid profile
·         Comprehensive metabolic panel – status of kidneys, liver, electrolyte and acid/base balance, blood sugar, blood proteins
·         Complete blood cell count -  red, white, platelets
·         High-sensitivity C-reactive protein
·         PSA for men
·         Thyroid stimulating hormone
·         Hemoglobin A1C – Measures long-term blood sugar

Daily aspirin reduces the risk of cancers of the gastrointestinal tract, prostate, lung, colon/rectum, esophagus {Anyone contemplating taking a daily aspirin should first check with his/her doctor as the drug increases the likelihood of potentially serious or even fatal internal bleeding}.

Genetic tests can show risk of cancer (breast, colon, lung, prostate, stomach, melanoma), autoimmune disease, vascular problems (aneurism, deep-vein thrombosis), macular degeneration, glaucoma, Alzheimer’s, multiple sclerosis, restless leg syndrome, atrial fibrillation, heart attack, Crohn’s disease, celiac disease, type II diabetes, obesity, osteoarthritis, and dose-response to drugs. {Of course, Agus’s company would be the obvious candidate to do such testing}.

Even though Vitamin D has looked good in some observational studies, it was associated with a rise in falls and fractures in older women. High blood levels of Vitamin D may also be associated with an increased risk of more aggressive forms of prostate cancer. {While it still appears that Vitamin D supplementation is advisable, particularly in less sunny parts of the world, large daily dosages (in excess of 1,000 IU) should likely be avoided}.

Antioxidants can worsen cancer because the body uses free radicals to fight bacteria and cancer. Free radical oxidation is a normal part of energy production, immune reactions, and cell signaling. {This is one of the most important points in the book. Most books and articles today suggest that the more anti-oxidants the better. However, supportive evidence applies mainly to eating foods high in antioxidants rather than taking antioxidant supplements. Also, Agus points out that Vitamin C can be health-promoting if you don’t have cancer, but it can actually enhance the growth of cancerous tumors once they invade your body.}

In a large trial, beta carotene increased the risk of mortality, and showed an increased risk of lung cancer in a Finnish study, while vitamin E increased the risk of hemorrhagic stroke but decreased the risk of ischemic stroke. Heavy vitamin use was associated with an increase in the more deadly form of prostate cancer. {Agus is generally against vitamin supplementation, especially in megadoses, and he makes a fairly strong case.}

Keep a strict, predictable schedule of eating, sleeping, and exercise, even on weekends. {I think this is one of the weakest parts of the book. Agus is adamant about the importance of keeping on a regular schedule, but he presents the barest of evidence to support his case. Humans are by nature flexible and adaptable. I don’t see any harm at exercising at different times of day if that is what you can fit into your schedule. It’s certainly better than skipping exercise sessions.}

Reduce inflammation by wearing comfortable shoes daily, getting an annual flu vaccine, and asking your doctor about taking a statin and daily baby aspirin. {Caution: A recent study showed that statins increase the likelihood of memory problems and diabetes. Aspirin can increase the risk of bleeding. So either of these drugs should only be used when needed and for people who can well tolerate them. A more natural way to prevent inflammation is to eat a diet high in vegetables and fruit and low in saturated fats and cholesterol.}

Because the causes of death among men are ranked as follows, exercise is extremely important for health (the numbers in parenthesis represent percent contribution to death risk). {It may seem surprising that obesity is low on the list, but that is likely because it represents the risk of obesity independent of all the other risk factors. But we know that obesity actually increases the likelihood of all the other risk factors except smoking. So it is still important to avoid obesity.

  1. Low cardio-respiratory fitness (15)
  2. Hypertension (14)
  3. Smoking (8)
  4. High cholesterol ( 4)
  5. Diabetes (4)
  6. Obesity (2)
Sitting for long periods has strong negative health effects even if we also exercise daily. {Recent studies have supported this point.}

Share your medical information whenever possible. {I feel that, in his enthusiasm about potentially having an enormous database with which to analyze disease risk, Agus totally fails to recognize the privacy concerns of patients. How can one be sure that one’s personal medical information will not be used to deny medical or life insurance coverage, inflate rates, or discriminate in hiring based on perceived disease risk?}

Don’t disturb the body’s homeostasis via excess drugs, supplements, inconsistent schedules, sleep deprivation, or excessive eating, drinking, or exercising. {Yes, it is possible to exercise too much. The main threat of too much exercise is overtraining syndrome, characterized by fatigue, irritability, sleep disturbance, and a decline in physical performance. It can take weeks or months to recover from severe overtraining syndrome, so it is best to be sensitive to symptoms.}



Wednesday, September 21, 2011

Tips On Improving Your Cholesterol Profile

The beneficial effects on the heart and circulatory system of a having a low blood level (below 130) of LDL cholesterol and a high blood level (above 55) of HDL cholesterol are well established. It is also good to have a ratio of total cholesterol to HDL cholesterol of no more than 4.0. If your levels don’t meet these criteria, you might benefit from the recommendations listed in an online Men’s Health Magazine article by Bill Phillips dated September 13, 2011. It presents the following ways, purportedly based on scientific studies, of improving your cholesterol profile without drugs:

Raise Your HDL Level


  • Eat at least 2 oz (57 gm) of nuts per day.
  • Do endurance exercise at least 20 min/day
  • Do 3 sets of 6-8 reps of the half squat, leg extension, and leg press, with 2 min max rest between sets, 2x/wk
  • Take a 1000 mg calcium supplement daily with 400 IU of Vitamin D-3
  • Eat fresh, not processed, white fish (e.g. cod, sole, flounder)
  • Take a daily 10-20 mg polycosanol supplement
  • Drink cranberry juice
  • Eat 2.5 oz of dark chocolate daily
Lower Your LDL Level
  • Eat a grapefruit daily
  • Eat several small meals a day
  • Eat food fortified with oat bran
  • Switch from a margarine containing trans fats to a spread that doesn’t
  • Drink Concord grape juice
  • Take phytosterol or phytostanol supplements in pills or margarine form
  • Add whole grains, nuts, and beans to your diet
Bottom Line

These seem like good recommendations. Just observe the following precautions:
  • Don’t overdo the calories by adding these items to your diet. Remove other items when you add these.
  • Endurance exercise is important for everyone. Weight training alone is not optimal for health.
  • Do not exceed 1000 mg of calcium/day from all sources (1200 mg/day if you're over 70) because of a possible increased risk of prostate cancer.
  • Don’t eat only white fish, because darker, fattier fish like salmon and mackerel are high in beneficial omega-3 fish oil.
  • Don’t overdo the juice because even natural juices contain a lot of sugar, especially fructose, which can increase fatty deposits in the liver and around the midsection.
  • Look for brands of dark chocolate without added milk fat.
  • Several small meals means SMALL.
  • The margarine brands that contain phytosterols and phytostanols contain some trans fats that are not listed because they're less than 0.5 mg per serving. So you may prefer getting these supplements in tablet form.

 

Monday, September 12, 2011

Important Information About Vitamins

An article in the September 2011 issue of the Nutrition Action Health Letter, published by the Center for Science in the Public Interest, examined research data on the value of taking multivitamins. Key points of the articles are:

Three major studies with a total of 426,000 study subjects over the age of 40 showed no difference between those who took and those who didn’t take multi-vitamins as to lifespan or the incidence of cardiovascular disease, cancer, or stroke.

Other studies showed no effect of multi-vitamin use on the incidence of colds, other infections, length of illness, or absence from school, work or other planned activities.

Cognitive performance was not improved in various study groups that took multi-vitamins for 6-12 months

However, the U.S. Dietary Guidelines Advisory Committee found that the following nutrients that are deficient among a large number of Americans:

  • Vitamin D
  • Folic acid
  • Vitamin B-12
  • Iron (among women due to menstruation)
  • Calcium
Most brands of multivitamins do not provide large enough doses to cause harm. However, there is concern that some people may be ingesting enough of the following to increase their risk of health problems:
  • Folic acid: Too little folic acid can increase the risk of colorectal cancer, and pregnant women who are deficient in folic acid are at risk for having babies with neural tube defects. That is why the U.S. government now mandates that folic acid be added to grain products. However, there is some evidence that too much folic acid taken over several years can increase the risk of having colorectal pre-cancerous growths (adenomous polyps) as well as prostate cancer. Thus, it is prudent not to ingest more than 1,000 micrograms a day of folic acid. Some breakfast cereals contain 400 micrograms per serving, and many people eat more than the standard serving size. Eating such cereals every day as well as taking a multivitamin and eating fortified bread, pasta, or rice can easily lead to exceeding 1,000 micrograms. This can be prevented by avoiding multivitamins with more than 400 micrograms of folic acid and limiting consumption of cereals that are fortified with 400 micrograms of folic acid per serving (e.g. Kashi Heart to Heart, Total, Multigrain Cheerios, Kellog’s Mueslix, Product 19, Smart Start, and Special K Original).
  • Selenium: Although there is marginal evidence that selenium may lower the risk of certain types of cancer, a study showed that people who took 200 micrograms of selenium daily for 8 years were almost 3 times as likely to be diagnosed with diabetes than those who didn’t take the supplement. So it is best to avoid multivitamins that contain more than 100 micrograms of selenium.
  • Vitamin A: While a Vitamin A deficiency can cause various health problems, very few Americans are deficient in the vitamin. However, a study showed that excess Vitamin A (more than 1667 IU/day) doubled the risk of hip fracture among women. The safest alternative is to take a multivitamin that contains beta-carotene rather than Vitamin A. Beta carotene is converted to Vitamin A as needed by the body and doesn’t cause any harm itself.

Bottom Line
  • Unless you feel you can get all your needed nutrients from your food, take a multivitamin that has 100% of the recommended daily value of each vitamin, rather than taking megadoses.
  • It is advisable not to exceed 1000 micrograms per day of folic acid by avoiding multivitamins with over 400 micrograms per serving and limiting intake of breakfast cereals containing more than 200 micrograms per serving.
  • Limit selenium in supplements to 100 micrograms per day.
  • Limit Vitamin A in supplements to 100% of daily value (5000 IU). Or, even better, take a supplement that contains beta-carotene rather than Vitamin A.


Wednesday, August 24, 2011

Are dairy products healthy?



Many books and articles contain health recommendations based on little or no scientific evidence. So when making personal decisions about how to maintain and improve one’s health, it is important to look for books and articles based on solid studies, especially large, well-controlled ones. A good example of science-based health information can be found in the July/August 2011 issue of the Nutrition Action Health Letter, published by the Center for Science in the Public Interest. It evaluates the pros and cons of consuming dairy products, Some of its key points:

Bones
We all know that milk is a major source of dietary calcium, which is needed to maintain bone density. Recently however, some health writers have contended that eating animal protein lowers bone density. Because protein contains amino acids, the alleged mechanism is increased acidity of the blood, prompting the body to respond by leaching calcium from the bones to neutralize the acid. Since milk is a protein source, it is implicated in bone loss. However, scientific study has refuted this contention. In actuality, bone mineral density is higher among people who eat more protein and lower among people who eat less protein. Radio isotope studies that tracked actual deposition and depletion of calcium have verified that consumption of dairy foods does not increase bone loss as we age.

Colon Cancer
A major analysis by the Harvard School of Public Health of 10 studies conducted in 5 countries, involving over 500,000 people concluded that people who drank at least one cup of milk per day had a 15% lower risk of colon cancer than those who drank less than 2 cups per week. Similarly, people treated for colon cancer who took 1200 mg of calcium per day and who had an above-average Vitamin D level had 15% less chance of recurrent colon cancer than those who didn’t take the calcium. Twenty-five percent of experimental animals fed a high-fat diet low in fiber, calcium, Vitamin D, and folic acid, developed colon tumors, but those supplemented with calcium and Vitamin D got none.

Prostate Cancer
There is some inconsistent evidence that high calcium consumption (in excess of 1500 mg/day) may increase the risk of prostate cancer. Milk increases the body’s level of insulin-like growth factor-1 (IGF-1), a hormone that stimulates the growth of both muscle and bone, but may also stimulate prostate-cancer growth. Even though a study of men receiving a 1200 mg calcium supplement daily showed no prostate cancer increase, the article recommended that men limit their calcium intake from food and supplements combined to 1000 mg/day if under 70 years of age and 1200 mg/day if over 70.

Blood Pressure
Adding 2 servings per day of low-fat dairy foods to a diet rich in fruits and vegetables, lowered blood pressure even further. In addition, a study of 28,000 women over 10 years showed that those consuming at least 2 cups/day of low-fat dairy foods reduced their risk of high blood pressure by 10%.

Weight Loss
When restricted to the same number of calories per day, women consuming more dairy products showed no difference in weight loss than those who consumed less dairy. However, when allowed to eat all they wanted at the end of the study, the dairy group consumed fewer calories. The implication is that dairy may help control appetite. While the weight-loss results were equivocal, the women in the low-dairy group lost bone density in their hips, while the high-dairy group did not. This is an important finding, considering that dangerous loss in bone density is common among both women and men as they age.

Lactose Intolerance
Lactose is the sugar found in milk. The following is the lactose content of some dairy products:
  • 8 oz cup of milk: 12 grams
  • 6 oz cup of yogurt - 10 grams
  • 1 oz hard cheese or cream cheese - 1 gram or less
  • ½ cup cottage cheese - 4-5 grams
  • ½ cup ice cream - 4-5 grams
Many people think they are lactose-intolerant, However, the article cites evidence that between one-third and three-quarters of people who think they are lactose-intolerant are actually not so. Many of them show none of the typical symptoms of gas or diarrhea when lactose is put in their non-dairy drinks without their knowledge. Many people’s digestive systems can adjust to lactose by building up intestinal bacteria over a period of time. So the authors recommend that people who think they are lactose intolerant try to adjust to lactose by:
  • Limiting lactose to 12 grams at a time (the amount in one 8 oz glass of milk).
  • Consuming lactose along with other foods to give it more time to be digested
  • Eating dairy foods regularly to maintain lactose-digesting bacteria
  • Other Health Issues Related to Dairy Products
Diabetes
A study of 200,000 people over 20 years showed that those consuming 3-5 servings per day of dairy products had a 14% lower risk of Type II diabetes than those consuming less than 1.5 servings per day. However, it is not known whether that is an effect of the dairy products or another factor common to people who consume more dairy products.

Breast and Ovarian Cancer
Eight studies of 350,000 women in several countries did not find any link between milk consumption and breast cancer. However, research on 500,000 women in the U.S. and Europe did show a weak and marginally significant increased risk of ovarian cancer for women who consumed more than 30 grams of lactose per day. However, two major cancer research organizations did not feel the evidence was conclusive.

Bottom Line
Dairy products made from skim or one-percent milk can be considered health-promoting foods. They contain large quantities of calcium necessary for maintaining bone-density as we age. Also, most are excellent sources of protein (except products made primarily from milk fat, such as cream cheese and butter). Milk appears to help control blood pressure and avoid colon cancer, and may also help control appetite. However, high milk consumption may increase the risk of prostate cancer among men and ovarian cancer among women. Therefore, men should limit calcium consumption from food and supplements combined to 1000 mg/day below age 70 and 1200 mg/day above age 70. Adequate Vitamin D intake is essential for healthy bone mineralization, even if calcium intake is adequate. Many people are deficient in Vitamin D because of low sun exposure. Current recommendations for daily Vitamin D supplementation are in the neighborhood of 1,000-2,000 IU.

Additional Note
The main type of saturated fat found in milk (myristic acid) is particularly potent in raising blood cholesterol, specifically the harmful low-density variety (LDL). Because of that, consumption of milk fat should be very limited. High proportions of milk fat are found in cream, butter, ice cream, cheese (especially cream cheese and soft cheeses like Brie), whole milk, and 2% milk. That is why non-fat and 1% fat milk products are preferable. Unfortunately, many dishes popular in the U.S., such as cheese burgers cheese ravioli, macaroni and cheese, and pizza, contain large amounts of cheese. The evidence indicates that the cardiovascular health of Americans would benefit from a reduction in cheese consumption.

Wednesday, July 20, 2011

How to Avoid Inflammation of Your Arteries


Inflammation of the blood vessels and other bodily tissue has become increasingly recognized as being complicit in heart disease, arthritis, and decline of mental capacity. Fortunately, the choices we make concerning what and how much we eat and drink, and how much exercise we do, can dramatically influence the degree of inflammation we experience. The information presented herein concerning lifestyle factors that affect inflammation, comes from a review article by O’Keefe, Gheewala, and O’Keefe in the Journal of the American College of Cardiology (vol. 51, no. 3, 2008).

Meals that are high in calories, and/or contain easily digestible, quickly absorbable, calorie-dense processed food and drink result in spikes in blood glucose and triglycerides (blood-borne fats), overwhelming the body’s ability to process them. Oxidative free radicals are then produced which attack the lining of the arteries (endothelium), inflaming them, causing them to constrict, and building up fatty deposits (atherosclerosis). In contrast, smaller meals containing ingredients that digest more slowly (e.g. fiber) produce smaller surges in blood sugar and triglycerides, and are thus not inflammatory.

Even a single meal high in saturated fat results in an increase of triglycerides, oxidative free radicals and inflammation, which negatively affects the function of the endothelium, causing constriction of the arteries, and raising systolic blood pressure.

A high glycemic meal is one that causes a spike in blood glucose. The Glycemic Index rates foods in comparison to glucose. Foods scoring closer to 100 cause relatively large spikes in blood sugar, while foods scoring closer to zero produce relatively small spikes. See a table listing the glycemic index of various foods from Harvard medical school. The body often responds to high glycemic index foods with insulin surges that remove sugar from the blood and can actually result in low blood sugar (hypoglycemia), an ebb in energy, and hunger. Regularly eating this way predisposes one to excess fat on and around the organs below the abdominal muscles (visceral fat) which, in turn, leads to inflammation and insulin resistance and raises the risks of diabetes, high blood pressure, and cardiovascular disease.

Dietary changes that reduce the magnitude of the triglyceride spike following meals by 20% and 40% respectively have been shown to reduce the risk of coronary artery disease by 30% and 40%. In addition to avoiding foods with a high glycemic index, adding certain foods to the diet can slow down digestion and reduce the spikes in glucose, insulin, and triglycerides. For example, nuts eaten along with a high-carbohydrate meal slow digestion and reduces blood sugar spikes by 30-50%. This both reduces oxidative stress, and provides antioxidants that combat such stress. In fact, a Mediterranean diet supplemented with either 30 grams of nuts or olive oil was found to reduce systolic blood pressure, blood sugar, and biomarkers of inflammation significantly better than a low-fat diet. Eating nuts 5 times per week was found to reduce risk of diabetes and cardiovascular disease by 20-50%. Quality protein sources low in saturated fat have a similar beneficial effect. These include egg-whites, lean meats, fish, casein, and whey protein, among others. Fish oil lowers triglyceride levels by 16-40%.

As expected, physical exercise has a positive effect, reducing post-meal spikes in blood sugar and triglycerides. Exercise is most beneficial in this regard if it is done within 2 hours before or after a large meal. Loss of body fat by diet control and/or exercise can also reduce post-meal spiking of blood sugar and triglycerides.

Alcohol consumption shows a J-shaped relationship with inflammation and blood sugar spiking, in addition to various other health problems such as coronary artery disease, diabetes, stroke, dementia, and all-cause death, with the lowest levels of these problems at 1-2 drinks per day for men and 0.5-1 drink a day for women. The J-shape means that drinking no alcohol increases the risk of these problems somewhat, while drinking in excess greatly increases the risks of these problems.

Characteristics of Inflammatory Meals


  • High in calories
  • High in calorically-dense foods
  • High in saturated fat
  • High in refined carbohydrates
  • Contain foods with high glycemic index

Characteristics of Diets That are Not Inflammatory
  • Smaller meals spread over the day
  • Low in saturated fat
  • Low in, or free of trans fats
  • Low in processed carbohydrates
  • Low in foods with high glycemic index
  • High in unprocessed fruits and vegetables rich in antioxidants
  • High in nuts, seeds, and whole grains
  • Contain vinegar (1-2 tbsp eaten with a meal high in refined carbohydrates reduces the blood sugar spike by 25-35% and reduces hunger)
  • Moderate amounts of lean animal protein
  • Moderate amounts of beneficial fats such as fish oil and monounsaturated oils (e.g. olive,canola)
The following Foods High in Antioxidants Help Prevent Oxidative Damage to the Endothelium
  • Berries
  • Red wine
  • Chocolate
  • Tea
  • Pomegranates
  • Cinnamon (also reduces glucose spike caused by high-glycemic-index meal)
If you are concerned about the possibility of inflammation in your arteries, you can ask your doctor about testing the C-reactive protein level in your blood when you get a checkup. However, if your total cholesterol level is below 200 and your HDL level is above 55, it is very unlikely that you have a problem with arterial inflammation. If your C-reactive protein level is above 1.0 or the ratio of your total cholesterol level to your HDL level is above 4.0, you would likely benefit from following an anti-inflammatory diet and exercising regularly.

Friday, June 24, 2011

Cold Weather and Air Conditioning Can Raise Your Blood Pressure

High blood pressure, also called hypertension, is defined as a systolic pressure above 140 mm of mercury (mmHg) and/or a diastolic pressure above 90 mmHg. Hypertension increases the risk of several major health problems, including heart disease, stroke, and kidney disease. While it is widely recognized that excess sodium intake increases the risk of hypertension, few people know that the ambient temperature at which people live affects the risk of hypertension. And ambient temperature varies with the seasons of the year. The following studies provide evidence for the seasonal variation in blood pressure and risk of hypertension.

In a study by Woodhouse, Khaw, and Plummer, 96 men and women, aged 65-74 years had their blood pressure taken for a full year. It was found that both systolic (SBP) and diastolic blood pressure (DBP) were greatest during the winter for people with both normal and high blood pressure. There was four times the incidence of blood pressures above 160/90 mmHg in winter than in summer. In a strong seasonal trend, a 1 deg C (1.8 deg F) decrease in living-room temperature was associated with increases of 1.3 mmHg in SBP and 0.6 mmHg in DBP. The authors linked this to the greater incidence of cardiac-related deaths of the elderly in winter.

In a study by Brennan, Greenberg and Miall, blood pressure measurements taken for the Medical Research Council's treatment trial for mild hypertension were analyzed according to the month in which the readings were made. For all age, sex, and treatment groups, both systolic and diastolic pressures were higher in winter than in summer. Blood pressure was also highly and significantly related to maximum and minimum daily air temperature. The seasonal variations in blood pressure were greater in older than in younger people.

In a study by Fujiwara et al., blood pressure was measured on 25 hypertensive outpatients (mean age 57), who spent virtually the entire day indoors in both summer and winter. Both systolic and diastolic blood pressure in the morning and night-time periods were significantly higher in winter than in summer (respective differences of 7.5 and 4.1 mmHg in the morning and 8.2 and 4.5 mmHg at night). Despite the fact that the patients lived essentially indoors at a relatively stable environmental temperature, the seasonal variation in blood pressure was statistically significant.

In a study by Kimura et al. of the Department of Integrated Medicine, Kagawa University, Japan, 15 healthy elderly Japanese (mean age 79) measured their blood pressure at home each morning more than 25 times per month for 3 years. The highest levels of both systolic and diastolic blood pressures (129 and 81 mmHg) occurred in February, the coldest month (avg temp. 5.0 deg C, 41 deg F), while the lowest levels (117 and 73 mmHg) were observed in August, the hottest month (mean temp 29.2 deg C, 84.6 deg F). Thus, both systolic and diastolic blood pressure demonstrated a close inverse relationship to outdoor temperature. A one degree C (1.8 deg F) decrease in the mean outdoor temperature was associated with rises of 0.43 mmHg in systolic blood pressure (SBP) and 0.29 mmHg in diastolic blood pressure (DBP).

In a study by Hozawa et al. at the Tohoku School of Medicine in Japan, 79 male and female volunteers (mean age 72.7 years) measured their blood pressure at least once a month for 3 years beginning in September 2000. The mean number of measurements was 19.0 times per month. Blood pressure levels were lowest in the warmest months. A clear inverse association between temperature and blood pressure values was evident when the outside temperatures was above 10°C, producing a respective decrease in systolic and diastolic blood pressure of 0.40 and 0.28 mmHg for each 1 deg C (1.8 deg F) increment of outside temperature.

A study by Sinha et al. at Maulana Azad Medical College, in India, 275 females 18-40 years of age showed that the prevalence of hypertension based on SBP was 12.7% in summer and 22.2% in winter. The prevalence of hypertension based on DBP was 11.3% in summer vs. 26.6% in winter, a highly statistically significant difference. Overall prevalence of hypertension (SBP = 140 or DBP = 90 mm of Hg) was 1.9 times greater in winter than in summer.

Bottom Line

The temperature at which we live can affect our blood pressure. This is likely related to the fact that, when we are cold, the small arteries in our skin constrict to avoid loss of body heat. That creates resistance to blood flow, thus increasing pressure. When we are hot, the small arteries in the skin widen to allow more heat dissipation, thereby reducing resistance to blood flow. Also, we tend to perspire more when we are hot, thereby losing water and salt, both of which tend to increase blood pressure. The most common medications for reduction of blood pressure are diuretics, which promote loss of water and salt through urination. Sweating can accomplish similar results.

People with hypertension or prehypertension (systolic pressure 120-140) can help control their blood pressure by avoiding being cold. In summer, air conditioning use should be minimized. Most people can adjust to a room temperature of 77 degrees without feeling uncomfortable, and even higher temperatures in locales with low humidity. In winter, the home can be kept warm and, if that is not economically feasible, dressing warmly indoors is a viable alternative. Exercise can be used to warm the body as well.

References

Brennan, P.J., G. Greenberg, W.E. Miall, S.G. Thompson. Seasonal variation in arterial blood pressure. Br Med J (Clin Res Ed) 285 : 919, 2 October 1982.

Fujiwara, T., M. Kawamura, J. Nakajima, Jun, T. Adachi, K. Hiramori. Seasonal differences in diurnal blood pressure of hypertensive patients living in a stable environmental temperature. Journal of Hypertension, vol. 13, no. 12, 1995.

Hozawa A., S. Kuriyama, T. Shimazu, K. Ohmori-Matsuda, I. Tsuji. Seasonal variation in home blood pressure measurements and relation to outside temperature in Japan. Clin Exp Hypertens, vol. 33, no. 3, pp. 153-8, 2011.

Kimura, T., S. Senda, H. Masugata, A. Yamagami, H. Okuyama, T. Kohno, T. Hirao, M. Fukunaga, H. Okada, F. Goda. Seasonal blood pressure variation and its relationship to environmental temperature in healthy elderly Japanese studied by home measurements.Clin Exp Hypertens. 2010 Jan;32(1):8-12.

Sinha P, D.K. Taneja, N.P. Singh, R. Saha. Seasonal variation in prevalence of hypertension: Implications for interpretation.Indian J Public Health, vol. 54, no. 1, pp. 7-10, 2010.

Woodhouse, P.R., K.T. Khaw, M. Plummer. Seasonal variation of blood pressure and its relationship to ambient temperature in an elderly population. Journal of Hypertension, vol. 11, no. 11, 1993.

Tuesday, June 14, 2011

Updated List of the Most-Contaminated Fruits and Vegetables

We have all been well-informed that eating plenty of fruits and vegetables is good for our health. Yet there is a continuing problem with pesticide contamination. It is recommended that we avoid pesticide exposures that are more than a thousandth of the levels known to be toxic. Yet, a 2009 study by the Environmental Protection Agency found that about 40% of U.S. children have levels of at least one pesticide well above this limit.

The nonprofit organization, Environmental Working Group, while reaffirming that eating a lot of fruits and vegetables is good for our health, suggested that by avoiding the most pesticide-contaminated fruits and vegetables, and choosing the least-contaminated ones, we can lower pesticide residues in our bodies. To assist us in making such choices, the organization just published a list of the dozen most pesticide-contaminated fruits and vegetables, based on testing done in 2009 by the U.S. Department of Agriculture and the Food and Drug Administration. It also published a list of the 15 least-contaminated fruits and vegetables to provide us with healthy alternatives. The group estimates that by avoiding the “Dirty Dozen” (or buying organic versions of these items) and selecting from the “Clean 15” we can cut our pesticide exposure by 92%.

The Dirty Dozen - Most Contaminated Fruits and Vegetables (number 1 is the worst)
  1. Apples
  2. Celery
  3. Strawberries
  4. Peaches
  5. Spinach
  6. Nectarines (imported)
  7. Grapes (imported)
  8. Sweet bell peppers
  9. Potatoes
  10. Blueberries (domestic)
  11. Lettuce
  12. Kale/collard greens
The Clean 15 - Least Contaminated Fruits and Vegetables (Number 1 is the best)
  1. Onions
  2. Sweet corn
  3. Pineapples
  4. Avocados
  5. Asparagus
  6. Sweet peas
  7. Mangoes
  8. Eggplant
  9. Cantaloupe (domestic)
  10. Kiwi
  11. Cabbage
  12. Watermelon
  13. Sweet potatoes
  14. Grapefruit
  15. Mushrooms
Bottom Line
Obviously, buying all organic produce is the best alternative for health. However, most of us cannot or choose not to incur the major budget hit it would entail. So the next best alternative is to avoid the “dirty dozen” while selecting more items from the “clean 15 “ list. Going organic for selected items can still keep our food budgets from skyrocketing.