Body

Summaries of study evidence on various food, drinks, exercise and sleep. Choose a sub-section from the menu to narrow to a specific category. OBJECTIVITY zone.

Mar 132011
 

This post is in initial build-out status and may change.

General Information: Wikipedia entry

Cardiovascular

Studied Uses: Stroke

Studied Risks: Heart attack; high blood pressure

Coffee - Cardiovascular Evidence Summary - http://sheet.zoho.com

Overall Cardiovascular Score: -1.39

Behind the Score: The score is more complex than it appears at first glance. Case-control studies show increased risk for heart attack and ischemic stroke, particularly in the hour after consumption, among infrequent drinkers of coffee 1, and among those with risk factors for heart disease 2 3 or who are carriers of the “slow *1F allele” of the CYP1A2 gene, which produces slow caffeine metabolism. 4 Other negative effects on the score stem from studies showing a modest increase in blood pressure among coffee drinkers 5 and an increased risk of developing high blood pressure for those with the slow *1F allele. 6

On the other hand, large prospective cohort studies that spanned many years identified health benefits as well, mainly related to reduced relative risk for stroke 7, especially cerebral infarction 8 but also possibly subarachnoid hemorrhage 9. These benefits accrued over the long term among regular drinkers of more than 1 cup per day. Benefits seemed to attenuate at more than 2 cups per day, with other risks — such as risk for heart attack — possibly increasing at 3 cups per day. 10 It is important to note that prospective cohort studies are not randomized clinical trials, and some may rely on participants’ self-reported intake of coffee.

Notably, at least one prospective cohort study showed that tea appeared similarly effective at lower intake levels (2 cups a day). 11 Also, tea did not appear to raise stroke risk in the hour after consumption. 12

A 2008 prospective study of more than 120,000 people identified 13 a small reduction in all-cause mortality due to coffee consumption; however, this appears to be due to a “moderate” reduction in deaths from cardiovascular disease. Further study would be required to confirm this association.

Warnings and Special Notes: Based on study results, people with existing risk factors for heart disease may want to consult their doctor about the right level of coffee consumption for them.

What Now? An overarching review of coffee’s short- and long-term studied effects states that, “…. longer-term trials on the effects of coffee on biological risk factors are needed to bridge the gap in the data between short-term trials and cohort studies.” 14

What Can I Do? Coffee is readily available, if you choose to drink it. Because of pesticide use on conventional coffee crops 15, organic coffee may be worth the extra cost. Buying Fair Trade may reduce the risk of supporting exploitative producers.

Notes:

  1. Coffee and acute ischemic stroke onset: the Stroke Onset Study. Neurology, 2010.
  2. Transient Exposure to Coffee as a Trigger of a First Nonfatal Myocardial Infarction. Epidemiology, 2006.
  3. Coffee and alcohol consumption as triggering factors for sudden cardiac death: case-crossover study. Croatian Medical Journal, 2005.
  4. Coffee, CYP1A2 genotype, and risk of myocardial infarction. Journal of the American Medical Association, 2006.
  5. Blood pressure response to chronic intake of coffee and caffeine: a meta-analysis of randomized controlled trials. Journal of Hypertension, 2005.
  6. CYP1A2 genotype modifies the association between coffee intake and the risk of hypertension. Clinica Medica, University of Padova, 2009.
  7. Coffee consumption and risk of stroke in women. Circulation, 2009.
  8. Coffee and tea consumption and risk of stroke subtypes in male smokers. Stroke, 2008.
  9. Coffee Consumption and Risk of Stroke in Women. Stroke, 2011.
  10. Alcohol, smoking, coffee and risk of non-fatal acute myocardial infarction in Italy, European Journal of Epidemiology, 2001.
  11. Coffee and tea consumption and risk of stroke subtypes in male smokers. Stroke, 2008.
  12. Coffee and acute ischemic stroke onset: the Stroke Onset Study. Neurology, 2010.
  13. The relationship of coffee consumption with mortality, Annals of Internal Medicine, 2008.
  14. Coffee Consumption and Coronary Heart Disease: Paradoxical Effects on Biological Risk Factors versus Disease Incidence, Clinical Chemistry, 2008.
  15. Coffee, Conservation, and Commerce in the Western Hemisphere, Natural Resources Defense Council
Mar 252011
 

This post is in initial build-out status and may change.

General Information: Wikipedia entry

Studied Uses: General health

General Health

Fructose Evidence Summary - General Health - http://sheet.zoho.com

Overall Score: -2.25

Behind the Score: The preponderance of studies show various negative effects from fructose consumption, although the score is not staggeringly negative because most studies to date have been animal 1 or in vitro 2 studies, with the notable exception of a small double-blinded parallel-arm study 3 (which showed a link to visceral fat and decreased insulin sensitivity) and a large cohort study 4 (which showed a possible link to gout). Moreover, it’s becoming conventional wisdom that high-fructose corn syrup is unhealthy 5, despite counter-arguments of the Corn Refiners Association. But what about whole fruits, fruit juices and sweeteners like agave nectar? The answer is complicated. (See the “Warnings and Special Notes” and “What Can I Do?” sections below.)

Warnings and Special Notes: A recent in vitro study 6 showed that fructose fed pancreatic cancer cells — so even organic or raw fructose-based sweeteners do not seem like such a “free pass” anymore 7. To minimize fructose, the answer seems simple: Favor low-fructose vegetables and fruits, and avoid high-fructose products. Note: To reduce pesticide and GM food exposure, eat organic fruits and vegetables.

What Now? Further study is definitely warranted, as the pancreatic-cancer study mentioned above was in vitro and did not involve human subjects. In general, most studies performed to date have found fructose has negative effects in animals, in vitro, and in humans.

What Can I Do? Keep eating whole fruits — they are widely acknowledged to have far more benefits than drawbacks. If you’re concerned about sugar intake, refer to the fructose chart and choose fruits that have relatively low amounts. (Note: Cancer patients may want to read the Warnings and Special Notes section above.) Compared to whole fruits, fruit juices contain relatively large amounts of sugars and much less fiber, so choosing whole fruits instead is probably a better choice.

Regarding sweeteners, regular table sugar is about 50 percent glucose and 50 percent fructose. High-fructose corn syrup often has either 42 or 55 percent fructose 8 (plus, it is often made from genetically modified corn), and agave nectar can range from about 56 to 92 percent fructose 9. With regard to fructose-heavy sweeteners such as agave nectar, used in many raw and/or vegan food products, some in moderation may be acceptable unless further studies show definite negative effects. Proponents cite agave nectar’s low glycemic index, which means it doesn’t affect blood glucose as much as table sugar. However, use caution if you have or had cancer. If you would rather avoid agave nectar and fructose in general, there are (imperfect) alternatives, such as stevia and xylitol.

 

Mar 262011
 

This post is in initial build-out status and may change.

General Information: Wikipedia entry. Note: Melatonin is a natural hormone that is also available as a supplement. The Evidence Summary and Score below assess the benefits and/or risks of melatonin levels in general.

Studied Uses: General health, cancer

General Health

Melatonin - General Health Evidence Summary - http://sheet.zoho.com

Overall Score: 2.18

Behind the Score:

Evidence for beneficial effects of relatively high melatonin levels is piling up across many types of studies and in relation to many disorders and biomarkers. Experiments have variously studied sleep quality 1, ALS (Lou Gehrig’s disease) 2, behavioral disturbances in Alzheimer’s 3, and brain damage 4. Perhaps the biggest hope for melatonin is as a cancer protective, discussed below because the number of studies warrants a separate section.

That said, the majority of studies comprising the overall score assessed test subjects’ natural melatonin levels (based on working shift hours, natural sleep-and-wake cycles, or physiological factors such as BMI and age) rather than the value of melatonin supplementation. If planning to supplement, talk with a doctor to find the right dose, since it is quite possible to take too much melatonin. Even better may be increasing your own body’s production of melatonin through lifestyle changes.

For example, natural melatonin production may be suppressed by exposure to bright lights (such as computer screens) after dark. 5 And it doesn’t take that much light to suppress melatonin production. 6 Another study showed that women who routinely “were not asleep at or after 1:00 a.m.,” the time of highest melatonin production, had higher serum estradiol levels, which may be a risk factor for cancer. 7 Overall, light exposure at night appears to pose risks for humans, which this study from the Journal of Pineal Research does an excellent job of summarizing.

Warnings and Special Notes: Melatonin’s greatest effects may be in its naturally occurring form. Melatonin supplementation has not been sufficiently studied in pregnancy and breastfeeding.


Cancer

Melatonin - Cancer Evidence Summary - http://sheet.zoho.com

Overall Score: 1.96

Behind the Score:

Some studies that looked at natural melatonin levels found correlations between higher melatonin levels and lower cancer risk 8 9, although one prospective study in premenopausal women found no association and another found an increased risk in the two years after baseline measurement of melatonin levels and a decreased risk over the longer term. 10 (Researchers speculated that this result could reflect preexisting sub-clinical illness affecting baseline melatonin measurements in some women — in other words, they were already sick at the beginning of the study and their melatonin levels were high as a result!) Notably, most studies of melatonin supplementation did not identify a positive effect on cancer risk, recurrence risk, or biomarkers. For example, a double-blinded, randomized controlled trial of melatonin supplementation in postmenopausal breast cancer survivors found improved sleep with melatonin supplementation but not improved biomarkers 11 (caveat: The study was small and short-term, with 95 women studied over 4 months). Another study of melatonin use in people with metastatic brain cancer found no benefit; in fact, the people given melatonin supplements had shorter median survival times than historical control data would predict. 12 Conversely, it increased survival times for lung cancer patients who did not respond to initial chemotherapy. 13

Warnings and Special Notes: Melatonin’s greatest effects may be in its naturally occurring form. Melatonin supplementation also has not been sufficiently studied in pregnancy and breastfeeding.


What Now? More rigorous study is warranted, especially of supplementation.

What Can I Do? You can work to boost your body’s melatonin production by:

  • Going outside for at least half an hour each day and letting full-spectrum light reach your eyes (yes, that means no glasses or contacts during that time)
  • Getting to bed relatively early and at a consistent time;
  • Sleeping in a dark room or using a good eye mask;
  • Keeping the lights off if you need to get up in the middle of the night (be careful, though!);
  • Decreasing exposure to blue-spectrum light (such as your computer screen or television, or blue-spectrum fluorescent lights) after dark;

One possible mitigation for late-night computer users: Try Flux, an application for Windows, Mac OS X, and Linux that adjusts screen brightness and color spectrum to match the time of day.

All of this may be a tall order, since the modern urban lifestyle features a lot of bright lights and late nights. If you’re unwilling or unable to make lifestyle changes, or you’ve tried and think they aren’t helping enough, you can talk with your doctor about trying a melatonin supplement. This might or might not be right for you, but getting the dose right is definitely important.

 

Notes:

  1. Prolonged-release melatonin improves sleep quality and morning alertness in insomnia patients aged 55 years and older and has no withdrawal effects. Journal of Sleep Research, 2007.
  2. Reduced oxidative damage in ALS by high-dose enteral melatonin treatment. Journal of Pineal Research, 2006.
  3. Decreased Melatonin Levels in Postmortem Cerebrospinal Fluid in Relation to Aging, Alzheimer’s Disease, and Apolipoprotein E-{epsilon}4/4 Genotype. The Journal of Clinical Endocrinology & Metabolism, 1999.
  4. The protective role of melatonin in experimental hypoxic brain damage. Pediatrics International, 2005.
  5. Effects of VDT tasks with a bright display at night on melatonin, core temperature, heart rate, and sleepiness. Journal of Applied Physiology, 2003.
  6. Minimum light intensity required to suppress nocturnal melatonin concentration in human saliva, Neuroscience Letters, 1998.
  7. Light Exposure at Night, Urinary 6-Sulfatoxymelatonin, and Serum Estrogens and Androgens in Postmenopausal Japanese Women. Cancer Epidemiology, Biomarkers and Prevention, 2008.
  8. Urinary Melatonin Levels and Postmenopausal Breast Cancer Risk in the Nurses’ Health Study Cohort. Cancer Epidemiology, Biomarkers and Prevention, 2009.
  9. Urinary Melatonin Levels and Breast Cancer Risk. Journal of the National Cancer Institute, 2005.
  10. Urinary 6-Sulphatoxymelatonin levels and risk of breast cancer in premenopausal women: the ORDET cohort. Cancer Epidemiology, Biomarkers and Prevention, 2010.
  11. Randomized trial of oral melatonin supplementation in breast cancer survivors. Proceedings of the American Association for Cancer Research, 2010.
  12. Randomized Phase II Trial of High-Dose Melatonin and Radiation Therapy for RPA Class 2 Patients With Brain Metastases (RTOG 0119). International Journal of Radiation Oncology, 2007.
  13. Randomized study with the pineal hormone melatonin versus supportive care alone in advanced nonsmall cell lung cancer resistant to a first-line chemotherapy containing cisplatin. Oncology, 1992.
Apr 052011
 

This post is in initial build-out status and may change.

General Information: Wikipedia entry

Studied Uses: Cardiovascular. (More will be added here in the future.)

Cardiovascular

Qigong Evidence Summary - Cardiovascular - http://sheet.zoho.com

Overall Score: 5.06

Behind the Score: The score is significantly positive based on evidence from several small and short-term but relatively rigorous studies. Most of these studies involved fewer than 100 individuals, divided into at least two groups: a control group and a qigong group. One study also compared qigong plus medicine to medicine alone 1, while another compared a control group, an exercise group and a qigong group. 2 In both of these studies, qigong showed significant benefits. In another study, qigong and exercise proved to be equally effective in lowering blood pressure — both worked well over a period of 16 weeks. 3

A drawback of the studies is that, although randomized and controlled, most trials were by their nature not blinded.

Warnings and Special Notes: One case report described a 65-year-old woman who frequently practiced qigong. Following a stroke, her blood pressure when performing qigong was erratic, despite normal status when resting. 4 Although this was a single case report, it indicates that caution and monitoring may be warranted in people with truly precarious health who want to participate in qigong.

What Now? Most studies spanned less than a year, and in the majority of cases only a few months. These studies illustrated clear short-term benefits of qigong, especially for lowering blood pressure and improving cholesterol levels. The long-term benefits of qigong appear to be relatively unexplored. It is possible that these benefits could be even more striking.

What Can I Do? You can find a qigong teacher in your area by searching the Qigong Institute’s database of teachers, or by visiting a holistic health practitioner or center and asking if they can provide a referral.