Think about health when faced with tough decisions

Planning in advance to eat healthfully is quite easy – but what happens when you are confronted with an immediate decision between healthy and unhealthy food – especially when you are hungry?

Here’s an example: you’re at a party where everyone is munching on chips, cheesy dips, and greasy finger foods. You see a platter of raw vegetables and fresh fruit, but you feel tempted by the junk food. Do you stick with the produce or indulge in the calorie-laden snacks?  What goes on in your brain while you’re making that decision?

Subconsciously, we assign a certain value to each food, asking ourselves, “How will each of these foods taste? How healthy is each one? What is more important to me right now, taste or healthfulness?”

Vegetable platter. Flickr: Bruce Guenter


Junk food. Flickr: bloomsburys

Decision-making is thought to be controlled by part of the brain called the ventromedial prefrontalcortex (vmPFC), which also plays a role in regulating emotions and emotional reactions.  A 2009 study found that another region, the dorsolateral prefrontal cortex (dlPFC), may help the vmPFC to decide that healthfulness is more important when making food decisions.   In people who showed more self-control in their food choices, the vmPFC was activated by pictures of foods they had as healthy and foods they rated as tasty; however, in people with less self-control, the vmPFC was only activated by foods they rated as tasty, not the ones they rated as healthy. Also, those with more self-control had more activity in the dlPFC during food decisions.  These results suggest that the dlPFC may reduce the value that the vmPFC assigns to tempting unhealthy foods, helping us to exert self-control in our food decisions.1

So, can we choose to activate the dlPFC to have more self-control when making food decisions?  If so, how? 

That’s exactly the question that this research group’s newest study tried to answer. Subjects were asked to fast for at least three hours prior to the experiment. They were shown pictures of 180 different foods and asked to respond within three seconds “yes” or “no” to whether they’d want to eat the food.  Before they experiment, they were told that one of their choices would be randomly selected, and if they answered “yes” for that food, it would be served to them later. 

Before each group of 10 food photos, a message would be displayed on the screen saying either "consider the healthiness," "consider the tastiness," or "make decisions naturally." These messages were designed to shift the subjects’ attention toward either taste or health – if they were reminded to think about health, would it change their brain activity and cause them to make a healthier choice?

The answer was yes. After seeing the “consider the healthiness” message, subjects were less likely to choose unhealthy foods, and more likely to choose healthy-untasty foods.  They also said “no” to foods more often after seeing the “healthiness” message than after seeing the “naturally” message.  

What was going on in the brain? In response to pictures of healthy foods, the vmPFC showed more activity in the presence of the “healthiness” message compared to the other messages.  The dlPFC was more active in response to all of the food pictures in the presence of the “healthiness” message compared to the other messages.  This result suggests that the dlPFC was more able to help the vmPFC put more value on healthiness after the “healthiness” message.   The subjects made healthier choices when they were reminded to do so.2,3

The message here is that making the tough decisions between taste and health is easier than we think – if we can remind ourselves that health is the more important quality, we can alter the way the brain values the foods involved.  When faced with a decision between delicious healthy food and tempting unhealthy food, we can use reminders to shift our attention toward health:

    • Post sticky notes in your kitchen, or on your desk at work, saying “Choose the healthiest foods” or something similar.   

    • Make a sign that says “GOMBS* fight cancer in every bite.”

    • When you are looking at a menu in a restaurant, or making a food choice outside of your home, remind yourself “I choose to eat healthy foods,” or “I do not eat disease-causing foods.” Write these statements on a visible card you keep in your wallet or pocketbook.

    • As Dr. Fuhrman recommends, put a sign on your refrigerator that says “The salad is the main dish!” 

According to this research, reminders like these do work.  We can train ourselves (and our dlPFCs) to use healthfulness as the most important quality by which we value foods.

*GOMBS  = Greens, Onions, Mushrooms, Beans, Berries, Seeds

 

References:

1. Hare TA, Camerer CF, Rangel A: Self-control in decision-making involves modulation of the vmPFC valuation system. Science 2009;324:646-648.

2. Think healthy, eat healthy: Caltech scientists show link between attention and self-control. EurekAlert! http://www.eurekalert.org/pub_releases/2011-07/ciot-the072611.php. Accessed August 15, 2011.

3. Hare TA, Malmaud J, Rangel A: Focusing Attention on the Health Aspects of Foods Changes Value Signals in vmPFC and Improves Dietary Choice. J Neurosci 2011;31:11077-11087.


 

More reasons to maintain a healthy weight

Being overweight is not harmless – excess fat is the major factor responsible for insulin resistance and resultant type 2 diabetes, and a risk factor for a plethora of conditions including heart disease, stroke, hypertension, high cholesterol, liver disease, gallbladder disease, respiratory problems, arthritis, and infertility.1  Being overweight is thought to be responsible for over 100,000 new cancer cases each year in the U.S. alone, and both overweight and obesity are associated with a greater risk of death from all causes. 

Recent findings in the field of obesity research have given us two more reasons to keep one’s weight in check. 

  1. Excess weight may restrict blood flow to certain areas of the brain, impairing brain function and possibly fueling more overeating.
  2. Even just a few extra pounds on someone with a “normal” BMI may increase risk of death from heart disease.

1.  Brain function

brain

Obesity in mid-life is already known to increase the later risk of dementia, suggesting that excess weight has detrimental effects on the brain.2  The high blood pressure, arterial stiffness, and insulin resistance that come with excess weight could be the factors that harm the brain.

In this particular study, the researchers compared overweight and normal weight subjects (average BMI 28.43 and 21.79, respectively) using an imaging technique that measures blood flow in specific areas of the brain.  They focused on the prefrontal cortex, an area of the brain that governs focus, impulse control, and executive function (which includes decision-making, planning, and working toward goals).

In overweight subjects compared to normal subjects, they saw a decrease in blood flow to the brain overall, and also specifically to the prefrontal cortex.  Because of the unique functions of the prefrontal cortex in regulating impulse control, they concluded that excess weight has the potential for driving further overeating by reducing blood flow to this area.3

Conversely, another recent study has found that losing weight can improve memory.   Subjects underwent memory, concentration, and problem solving tests before and 12 weeks after bariatric surgery.  Memory performance had improved after 12 weeks.  Importantly, the baseline tests also revealed that the obese subjects and cognitive impairment. Of course, bariatric surgery is not a safe way to lose weight, but this study makes the point that the brain begins to work more effectively when excess fat begins to disappear.4

2.  Risk of death from coronary artery disease

heartObesity is a known risk factor for heart disease, but a new meta-analysis has reported that a little “excess belly fat” can increase the risk of death from coronary artery disease even for people whose body mass index (BMI) is in the normal range.   BMI is an imperfect indicator of the health risks associated with obesity, taking only height and weight, and not body fat percentage or fat distribution, into account. Many scientists believe that waist circumference and/or waist-to-hip ratio are better measures of overweight and obesity.  Certainly, these are better indicators of visceral fat, which is more metabolically active and thought to be more harmful. Nevertheless, both high BMI and large waist circumference are associated with increased risk of death.  

The meta-analysis included data on over 15,000 coronary artery disease patients, and found that those who had “central obesity” (which was evaluated based on waist circumference and waist-to-hip ratio) are at a greater risk of death.  This was true not only for obese patients, but normal weight patients as well.  In obese patients, central obesity increased risk by 93%, and in normal weight patients by 70%.5

In order to enjoy excellent health, in addition to eating high-nutrient foods, we must also strive to respond appropriately to the signals of true hunger so that we avoid overeating.  Too many calories, even from healthy natural foods, will translate into excess fat on the body and therefore health risks.

It should be noted that eating right gives you the ability to lose food addictions and be in better control of your cravings, but food is all around us and people can still overeat for recreation.  

 

References:

1. U.S. Centers for Disease Control and Prevention. Overweight and Obesity: Health Consequences. http://www.cdc.gov/obesity/causes/health.html 

2. Fitzpatrick AL, Kuller LH, Lopez OL, et al. Midlife and late-life obesity and the risk of dementia: cardiovascular health study. Arch Neurol. 2009 Mar;66(3):336-42.

3. Willeumier KC, Taylor DV, Amen DG. Elevated BMI Is associated With Decreased Blood Flow in the Prefrontal Cortex Using SPECT Imaging in Healthy Adults. Obesity (2011) 19, 1095–1097

4. Gunstad J, Strain G, Devlin MJ, et al. Improved memory function 12 weeks after bariatric surgery. Surg Obes Relat Dis. 2010 Oct 30. [Epub ahead of print]

5. Coutinho T, Goel K, Corrêa de Sá D, et al. Central obesity and survival in subjects with coronary artery disease a systematic review of the literature and collaborative analysis with individual subject data. J Am Coll Cardiol. 2011 May 10;57(19):1877-86.

 

Vitamin B12 may protect against Alzheimer 's disease

Vitamin B12 is required for important biological functions like red blood cell production, nervous system function, and DNA synthesis. Deficiency in B12 can cause a variety of problems including anemia, depression, confusion, fatigue, digestive issues, and nerve damage. [1]

Vitamins. Flickr: bradley jVitamin B12 is scarce in plant-based diets, and is a common deficiency, especially in the elderly. Of course, diets low in animal products and high in unrefined plant foods dramatically reduce the risk of chronic disease, but these healthful diets do require a supplemental source of vitamin B12. The rates of deficiency increase with age, and about 20% of adults over the age of 60 are either insufficient or deficient in vitamin B12.[2] Recent research has suggested that the current recommendations for B12 intake may be inadequate – not just for the elderly, but even for young people who have adequate absorption capability. Therefore supplementation with vitamin B12 is likely important for most people, and absolutely required for most vegans to achieve sufficient B12 status.[3]

When vitamin B12 takes part in DNA synthesis, it helps to convert the amino acid homocysteine to methionine, therefore lowering homocysteine levels. [1] Elevated homocysteine is a known risk factor for cardiovascular disease. Since B12 is important for nervous system function, and many cardiovascular disease risk factors are also risk factors for Alzheimer’s disease, scientists hypothesized that adequate vitamin B12 levels would be protective, and elevated homocysteine would be detrimental with respect to the development of Alzheimer’s. They investigated the relationship between homocysteine, B12, and Alzheimer’s disease diagnosis in a group of 271 healthy older persons (65-79 years of age) over the course of 7 years. Elevated homocysteine was associated with increased risk, and increased B12 with decreased risk of Alzheimer’s disease. [4]

Future studies will evaluate the effectiveness of vitamin B12 supplementation as a preventive measure against dementia, but we don’t need to wait for those results – we already know that B12 is an important supplement to take, and Alzheimer’s prevention may turn out to be an added benefit of maintaining adequate B12 levels.

A health-promoting diet is the most effective way to maintain excellent health and protect against chronic diseases, including Alzheimer’s and other forms of dementia. But in order to enjoy the strongest protection possible, it is just as important to prevent deficiencies of certain nutrients that may be sub-optimal in an overall health-promoting diet, such as vitamin B12, zinc, DHA, and vitamin D, by taking the necessary supplements.

 

References:

1. Office of Dietary Supplements, National Institutes of Health. Dietary Supplement Fact Sheet: Vitamin B12. November 18, 2010]; Available from: http://ods.od.nih.gov/factsheets/VitaminB12/.
2. Allen, L.H., How common is vitamin B-12 deficiency? Am J Clin Nutr, 2009. 89(2): p. 693S-6S.
3. Bor, M.V., et al., Daily intake of 4 to 7 microg dietary vitamin B-12 is associated with steady concentrations of vitamin B-12-related biomarkers in a healthy young population. Am J Clin Nutr, 2010. 91(3): p. 571-7.
4. Hooshmand, B., et al., Homocysteine and holotranscobalamin and the risk of Alzheimer disease: a longitudinal study. Neurology, 2010. 75(16): p. 1408-14.

 

Does omega-3 supplementation during pregnancy prevent postpartum depression? Improve baby's brain development?

Omega-3 fats are essential – we must take them in from our diets because our body cannot synthesize them. These fats are extremely important for many facets of our health, especially the health of the brain and cardiovascular system.[1] Omega-3 fat is a major structural component of brain cell membranes and the retina – about 60% of the dry weight of the brain is made up of fat, and DHA is the most abundant fat in the brain. [2]
 

As such, DHA is an essential factor in early brain development, and maintaining adequate levels during pregnancy is believed to benefit the child’s cognitive development.[3] The current consensus is that pregnant women should consume at least 200 mg DHA each day to promote normal fetal brain development. Pregnant women are also urged to limit fish consumption because of mercury contamination, which is harmful to the brain of the developing baby.[4] Fish oil or vegan DHA supplements are therefore an attractive option for pregnant women.

Pregnant woman
In 2009, the results of three randomized controlled trials were pooled and showed that babies given supplemental DHA in formula scored higher on a problem solving test at 9 months of age than babies given control formula. However, there is some disagreement in the literature as to whether DHA supplementation during pregnancy and infancy actually improves cognitive development in the child.[5]


A recently published study in the Journal of the American Medical Association reported an unexpected finding: Pregnant women who took fish oil capsules (800 mg DHA and 100 mg EPA per day) compared to vegetable oil placebo capsules did not have lower incidence of postpartum depression, and their children did not have improved cognitive development at 18 months of age.[6]
Of course, this does not mean that pregnant women shouldn’t bother taking DHA. The developing baby’s only source of DHA for beginning to build its brain tissue is its mother’s dietary intake. DHA supplementation also reduces the risk of preterm birth – a factor known to be associated with compromised cognitive development in the infant and maternal depression.[7]
In reference to the lack of effect on symptoms of depression, the therapeutic effects of omega-3 supplements on depression are due mostly to EPA rather than DHA, according to a recent meta-analysis. [8] I recommend omega-3 supplementation including 1,000 mg of EPA to treat depression – the relatively low dose of EPA used in this trial may therefore be responsible for the lack of effect on depression in this study.


An editorial published in response to the study stated potential reasons why this outcome occurred – these comments also shed light on why there seem to be discrepancies in the medical literature on this subject. One possibility is that the criteria used to measure infant brain development in this study were not sufficiently sensitive to detect small but important differences in cognition in 18-month olds. The criteria used were based on global measures of cognition, and are not designed to detect differences in specific processes such as memory, attention, and problem-solving.[7] As mentioned above, previous studies have seen differences in problem solving in infants given supplemental DHA.[5] Furthermore, there are several cognitive functions that cannot be accurately measured until children reach preschool and school age – the editorial cites a smaller study of fish oil supplementation during pregnancy that found enhanced IQ scores in 4 year olds.[9] I agree that it isn’t possibly to reliably measure intelligence in an 18-month old, and that better results would come from studies that measure cognitive function once the children are in school.


DHA is a vital component of brain tissue, and pregnant women should take at least 200 mg each day to prevent preterm birth and support normal fetal brain development to assure maximum intelligence.

 

References:

1. Yurko-Mauro, K., Cognitive and cardiovascular benefits of docosahexaenoic acid in aging and cognitive decline. Curr Alzheimer Res, 2010. 7(3): p. 190-6.
2. Muskiet, F.A., et al., Is docosahexaenoic acid (DHA) essential? Lessons from DHA status regulation, our ancient diet, epidemiology and randomized controlled trials. J Nutr, 2004. 134(1): p. 183-6.
3. Ryan, A.S., et al., Effects of long-chain polyunsaturated fatty acid supplementation on neurodevelopment in childhood: a review of human studies. Prostaglandins Leukot Essent Fatty Acids, 2010. 82(4-6): p. 305-14.
4. Koletzko, B., I. Cetin, and J.T. Brenna, Dietary fat intakes for pregnant and lactating women. Br J Nutr, 2007. 98(5): p. 873-7.
5. Drover, J., et al., Three randomized controlled trials of early long-chain polyunsaturated Fatty Acid supplementation on means-end problem solving in 9-month-olds. Child Dev, 2009. 80(5): p. 1376-84.
6. Makrides, M., et al., Effect of DHA supplementation during pregnancy on maternal depression and neurodevelopment of young children: a randomized controlled trial. JAMA, 2010. 304(15): p. 1675-83.
7. Oken, E. and M.B. Belfort, Fish, fish oil, and pregnancy. JAMA, 2010. 304(15): p. 1717-8.
8. Martins, J.G., EPA but not DHA appears to be responsible for the efficacy of omega-3 long chain polyunsaturated fatty acid supplementation in depression: evidence from a meta-analysis of randomized controlled trials. J Am Coll Nutr, 2009. 28(5): p. 525-42.
9. Helland, I.B., et al., Maternal supplementation with very-long-chain n-3 fatty acids during pregnancy and lactation augments children's IQ at 4 years of age. Pediatrics, 2003. 111(1): p. e39-44.

 

Football players face damage to the cardiovascular system and brain

Body size is known to be inversely related to longevity – both tall stature and large weight have been linked to increased early-life mortality in epidemiological studies. [1, 2]

So it makes sense that football linemen maintaining a high body mass for competitive reasons would likely be sacrificing years of life for their large size. Indeed, retired NFL linemen are said to have an increased rate of premature death, specifically cardiovascular death. [3, 4] A contrasting hypothesis states that football linemen’s high level of exercise would protect them from the cardiovascular risks associated with their large size. However, recent research has found that they are not protected.

Cardiovascular and metabolic parameters were compared in current professional football players and baseball players. The baseball players did show an increased prevalence of hypertension compared to the general U.S. population, but otherwise had favorable levels of cardiovascular risk factors. However, the football players, linemen in particular, had higher rates of obesity, hyperglycemia, and cardiometabolic syndrome (defined as 3 or more risk factors) compared to baseball players. Linemen also had increased rates of high blood pressure, diabetes, glucose intolerance , and obesity compared to the general U.S. population. [5, 6] The researchers concluded that these large athletes are not in peak physical condition – their time spent exercising heavily does not outweigh the negative health effects of their large size.

"For the population in general, the concept that you can be both fat and fit may simply not be true." According to Dr. John Helzberg of the University of Missouri-Kansas City School of Medicine, one of the researchers.

The researchers also expressed concern that the next generation of players, now high school and college athletes, will be encouraged to grow larger to be more competitive, to the detriment of their future health. [7]. We also know that the high animal protein intake utilized to get that large dramatically increases IGF-1 (insulin-like growth factor-1) and the link between increased IGF-1 and cancer. [8, 9]

In addition, high school football players may already be compromising their brain health because of the repeated head trauma inherent in their chosen sport. Motion of the brain within the skull can damage nerve cells and synapses, and a research group at Purdue University hypothesized that there may be additive effects of repeated head trauma even if individual impacts do not produce any symptoms. They conducted a complex study using helmet-based sensors, video, cognitive tests, and functional MRI (fMRI) to determine neurological changes in high school football players due to head trauma.

Data from the helmet sensors reported forces of up to 100 G sustained upon impact – for reference, most rollercoasters expose riders to forces of only 5 G. Players that showed symptoms (concussion) were expected to have neurological changes, and indeed did. Notably though, of the players who received a high number of or unusually hard impacts, half of those that showed no symptoms still suffered cognitive impairments, based on cognitive tests and fMRI performed before, during, and after the season. They showed deficits in visual working memory and also altered activation in a part of the brain in close proximity to the most frequent area of impact. This is a significant finding - players that didn’t have any symptoms likely went on playing after hard impacts, not realizing they risk further head trauma and further and more serious neurologic injury and intellectual deterioration. [10, 11]

The human body must be properly cared for in order to remain healthy. Similar to consistently eating a low-nutrient diet, growing the body unnaturally large and subjecting the head to repeated hard impacts may not produce immediate symptoms, but set the stage for future disease.

 

 

References:

1. Samaras, T.T. and H. Elrick, Height, body size, and longevity: is smaller better for the human body? West J Med, 2002. 176(3): p. 206-8.
2. Samaras, T.T., L.H. Storms, and H. Elrick, Longevity, mortality and body weight. Ageing Res Rev, 2002. 1(4): p. 673-91.
3. Croft, L.B., et al., Comparison of National Football League linemen versus nonlinemen of left ventricular mass and left atrial size. Am J Cardiol, 2008. 102(3): p. 343-7.
4. Selden, M.A., J.H. Helzberg, and J.F. Waeckerle, Early cardiovascular mortality in professional football players: fact or fiction? Am J Med, 2009. 122(9): p. 811-4.
5. Helzberg, J.H., et al., Comparison of cardiovascular and metabolic risk factors in professional baseball players versus professional football players. Am J Cardiol, 2010. 106(5): p. 664-7.
6. Selden, M.A., et al., Cardiometabolic abnormalities in current National Football League players. Am J Cardiol, 2009. 103(7): p. 969-71.
7. American College of Gastroenterology (2009, October 30). For Big Athletes, Possible Future Risk: Heightened Cardiometabolic Risk Factors Among Professional Football Linemen. ScienceDaily. . 2009.
8. Allen, N.E., et al., Hormones and diet: low insulin-like growth factor-I but normal bioavailable androgens in vegan men. Br J Cancer, 2000. 83(1): p. 95-7.
9. Kaaks, R., Nutrition, insulin, IGF-1 metabolism and cancer risk: a summary of epidemiological evidence. Novartis Found Symp, 2004. 262: p. 247-60; discussion 260-68.
10. Purdue University (2010, October 8). Brain changes found in high school football players thought to be concussion-free. ScienceDaily. . 2010.
11. Talavage, T.M., et al., Functionally-Detected Cognitive Impairment in High School Football Players Without Clinically-Diagnosed Concussion. J Neurotrauma, 2010.

 

Vitamin D update: Diabetes, cognitive decline, asthma, and heart attack

Vitamin D is continuing to make news.  Although previously well-known for its effects on calcium absorption and therefore bone health, vitamin D has now emerged as a contributor to many nonskeletal physiological processes, and functions have been attributed to vitamin D in the prevention of cancer, cardiovascular disease, infections, autoimmune diseases, and more. There are vitamin D receptors in almost every cell in the human body, and vitamin D regulates the expression of over 200 different genes. It is not surprising that sufficient vitamin D is crucial to the proper function of so many of our body’s tissues.1

Scientists estimate that 50% of the population of North America and Western Europe has insufficient blood vitamin D levels (as measured by 25(OH)D; sufficient is defined as greater than 30 ng/ml). Although recommended vitamin D intakes remain at only 200-400 IU per day, there is consensus among the scientific community that 2000 IU or more may be necessary for most  people to maintain sufficient blood levels.2

The newest research has found that vitamin D sufficiency is important for preventing type 2 diabetes, cognitive decline, asthma, and cardiovascular disease.

 

 

 

Type 2 diabetes

There is some evidence that vitamin D is involved in insulin secretion by pancreatic beta cells, since insulin secretion is a calcium-dependent process. Vitamin D may also prevent the development of insulin resistance by stimulating expression of the insulin receptor on the surface of cells that use glucose as fuel.3 A recent study performed at Johns Hopkins University School of Medicine on type 2 diabetics found that 91% of the patients were either deficient (less than 15 ng/ml) or insufficient (between 15 and 30 ng/ml) in vitamin D. Furthermore, there was inverse association between vitamin D levels and HbA1c, an indicator of blood glucose levels over the preceding 2-3 months, implying that vitamin D sufficiency contributes to glycemic control in diabetics.4 Vitamin D’s effects are not specific to type 2 diabetes; there is also convincing evidence that vitamin D supplementation during pregnancy and early childhood can reduce the risk of type 1 diabetes, and prospective studies on this topic are ongoing.1,5

Cognitive decline

Vitamin D receptors are present throughout the entire human brain, and genes that are regulated by vitamin D are involved in processes such as memory formation and neurotransmission.6,7 Although previous studies have been inconclusive8, this new data supports a role for vitamin D in maintaining brain health in older adults. 

Asthma

Two recent studies on asthma, one in adults and one in children, has linked vitamin D insufficiency with increased asthma severity.9 Those with 25(OH)D levels above 30 ng/ml had greater lung function, and used less medication.10 A similar study in children also found that lower vitamin D levels were associated with increased asthma severity, and that higher vitamin D levels were associated with reduced odds of hospitalization for asthma.11 Vitamin D’s anti-inflammatory actions or regulation of smooth muscle cell contraction via calcium handling may be the responsible factors. The researchers are currently conducting a trial investigating vitamin D supplementation as a therapeutic option for asthma. Vitamin D is also important for lung development in utero, so maternal supplementation with vitamin D during pregnancy is recommended.12

Cardiovascular disease

There is continually building evidence in the literature that sufficient vitamin D levels protect against cardiovascular disease. Vitamin D deficiency is extremely prevalent among heart attack sufferers – 96% of heart attack sufferers in a recent study were either insufficient (21%) or deficient (75%) in vitamin D. Those with sufficient vitamin D levels are less likely to die from heart attack or stroke.  Vitamin D insufficiency may allow for increased cholesterol uptake by inflammatory cells, which contributes to atherosclerosis.13 A newly published study recorded vitamin D levels at baseline and throughout 6 years of follow-up. At the start of the study, the average 25(OH)D level was 19.3 ng/ml (insufficient). During the trial, about half of the subjects increased their levels to the sufficient range (above 30 ng/ml), and these subjects had significantly reduced incidence of heart attack, heart failure, and coronary artery disease. Some subjects raised their 25(OH)D levels above 44 ng/ml, and they received even stronger protection against cardiovascular disease. Compared to those who reached levels above 44 ng/ml, those whose levels stayed between 10 and 19 ng/ml had a 27% increase in coronary artery disease, a 32% increase in heart failure, and a 59% increase in heart attack incidence.14

Maintaining sufficient vitamin D levels is essential to our health. 

Very few foods naturally contain vitamin D and we cannot rely on sun exposure alone because of indoor jobs, cool climates, and the risk of skin cancer that may arise from adequate amounts of sun exposure to maintain vitamin D levels.   Plus, requirements vary with genetics and skin type greatly effecting Vitamin D production in the skin.  Taking a multivitamin is not the answer because almost all  multivitamins still provide an inadequate amount of vitamin D (400 IU). Favorable levels can be confirmed with a blood test, and supplementation can be adjusted accordingly.   I recommend supplementing with an adequate amount of vitamin D in order to maintain 25(OH)D levels of 35-55 ng/ml. For some people 2000 IU will be sufficient, but others may require more.

References:

1. Hyppönen E. Vitamin D and increasing incidence of type 1 diabetes-evidence for an association? Diabetes Obes Metab. 2010 Sep;12(9):737-43.

2. University of California - Riverside (2010, July 19). More than half the world's population gets insufficient vitamin D, says biochemist. ScienceDaily. Retrieved July 28, 2010, from http://www.sciencedaily.com /releases/2010/07/100715172042.htm

3. Pittas AG, Lau J, Hu FB, Dawson-Hughes B. The role of vitamin D and calcium in type 2 diabetes. A systematic review and meta-analysis. J Clin Endocrinol Metab. 2007 Jun;92(6):2017-29.

4. The Endocrine Society (2010, June 21). Poor control of diabetes may be linked to low vitamin D. ScienceDaily. Retrieved July 28, 2010, from http://www.sciencedaily.com /releases/2010/06/100621091209.htm

5. Zipitis CS, Akobeng AK. Vitamin D supplementation in early childhood and risk of type 1 diabetes: a systematic review and meta-analysis. Arch Dis Child. 2008 Jun;93(6):512-7.

6. McCann JC, Ames BN. Is there convincing biological or behavioral evidence linking vitamin D deficiency to brain dysfunction? FASEB J. 2008 Apr;22(4):982-1001.

7. Llewellyn DJ, Lang IA, Langa KM, et al. Vitamin D and Risk of Cognitive Decline in Elderly Persons Arch Intern Med. 2010;170(13):1135-1141.

8. Annweiler C, Allali G, Allain P, et al. Vitamin D and cognitive performance in adults: a systematic review. Eur J Neurol. 2009 Oct;16(10):1083-9.

9. EurekAlert! Low vitamin D levels associated with more asthma symptoms and medication use. http://www.eurekalert.org/pub_releases/2010-04/njma-lvd041510.php#

Jancin B. Vitamin D Tied to Airway Hyperresponsiveness. Family Practice News. May 1, 2010.

10. Sutherland ER, Goleva E, Jackson LP, et al. Vitamin D levels, lung function, and steroid response in adult asthma. Am J Respir Crit Care Med. 2010 Apr 1;181(7):699-704.

11. Brehm JM, Celedón JC, Soto-Quiros ME, et al. Serum vitamin D levels and markers of severity of childhood asthma in Costa Rica. Am J Respir Crit Care Med. 2009 May 1;179(9):765-71.

12. Litonjua AA. Childhood asthma may be a consequence of vitamin D deficiency. Curr Opin Allergy Clin Immunol. 2009 Jun;9(3):202-7.

13. Washington University School of Medicine (2009, August 25). Why Low Vitamin D Raises Heart Disease Risks In Diabetics. ScienceDaily. Retrieved July 28, 2010, from http://www.sciencedaily.com /releases/2009/08/090821211007.htm

14. Jancin B. CAD Events Less Likely With Normal Vitamin D. Family Practice News, May 15, 2010.