Eating a diet rich in omega-3 fatty acids appears to protect seniors against the onset of a serious eye disease known as age-related macular degeneration (AMD). Researchers did a fresh analysis of a one-year dietary survey conducted in the early 1990s. The poll involved nearly 2,400 seniors between the ages of 65 and 84 living in Maryland’s Eastern Shore region, where fish and shellfish are eaten routinely.
While participants in all groups, including controls, averaged at least one serving of fish or shellfish per week, those who had advanced AMD had consumed less fish and seafood containing omega-3 fatty acids. After their food intake was assessed, participants underwent eye examinations. About 450 had AMD, including 68 who had an advanced stage of the disease, which can lead to severe vision impairment or blindness. Prior evidence suggested that dietary zinc is similarly protective against AMD, so the researchers looked to see if zinc consumption from a diet of oysters and crabs reduced risk of AMD, but no such association was seen.
The researchers believe that the low dietary zinc levels relative to zinc supplements could account for the absence of such a link. However, they cautioned against people to start taking omega-3 supplements to protect against AMD based on this study because they are not sure that the above results have sufficient power to draw any conclusions. The correlation is important but larger studies with longer term follow-up are needed before being able to properly assess the impact.
The vitamin D levels of newborn babies appear to predict their risk of respiratory infections during infancy and the occurrence of wheezing during early childhood, but not the risk of developing asthma. Results of a study in the January 2011 issue of Pediatrics support the theory that widespread vitamin D deficiency contributes to risk of infections.
“Our data suggest that the association between vitamin D and wheezing, which can be a symptom of many respiratory diseases and not just asthma, is largely due to respiratory infections,” says Carlos Camargo, MD, DrPH, of the Massachusetts General Hospital (MGH), who led the study. “Acute respiratory infections are a major health problem in children. For example, bronchiolitis – a viral illness that affects small airway passages in the lungs – is the leading cause of hospitalization in U.S. infants.”
Although vitamin D is commonly associated with its role in developing and maintaining strong bones, recent evidence suggests that it is also critical to the immune system. Vitamin D is produced by the body in response to sunlight, and achieving adequate levels in winter can be challenging, especially in regions with significant seasonal variation in sunlight. Previous studies by Camargo's team found that children of women who took vitamin D supplements during pregnancy were less likely to develop wheezing during childhood. The current study was designed to examine the relationship between the actual blood levels of vitamin D of newborns and the risk of respiratory infection, wheezing and asthma.
The researchers analyzed data from the New Zealand Asthma and Allergy Cohort Study, which followed more than 1,000 children in the cities of Wellington and Christchurch. Midwives or study nurses gathered a range of measures, including samples of umbilical cord blood, from newborns whose mothers enrolled them in the study. The mothers subsequently answered questionnaires – which among other items asked about respiratory and other infectious diseases, the incidence of wheezing, and any diagnosis of asthma – 3 and 15 months later and then annually until the children were 5 years old. The cord blood samples were analyzed for levels of 25-hydroxyvitamin D (25OHD) – considered to be the best measure of vitamin D status.
Cord blood samples were available from 922 newborns in the study cohort, and more than 20 percent of them had 25OHD levels less than 25 nmol/L, which is considered very low. The average level of 44 nmol/L would still be considered deficient – some believe that the target level for most individuals should be as high as 100 nmol/L – and lower levels were more common among children born in winter, of lower socioeconomic status and with familial histories of asthma and smoking. By the age of 3 month, infants with 25OHD levels below 25 nmol/L were twice as like to have developed respiratory infections as those with levels of 75 nmol/L or higher.
Survey results covering the first five years of the participants' lives showed that, the lower the neonatal 25OHD level, the higher the cumulative risk of wheezing during that period. But no significant association was seen between 25OHD levels and a physician diagnosis of asthma at age 5 years. Some previous studies had suggested that particularly high levels of vitamin D might increase the risk for allergies, but no such association was seen among study participants with the highest 25OHD levels. Camargo notes that very few children in this study took supplements; their vitamin D status was determined primarily by exposure to sunlight.
An associate professor of Medicine at Harvard Medical School, Camargo notes that the study results do not mean that vitamin D levels are unimportant for people with asthma. “There's a likely difference here between what causes asthma and what causes existing asthma to get worse. Since respiratory infections are the most common cause of asthma exacerbations, vitamin D supplements may help to prevent those events, particularly during the fall and winter when vitamin D levels decline and exacerbations are more common. That idea needs to be tested in a randomized clinical trial, which we hope to do next year.”
Co-authors of the Pediatrics paper are Ravi Thadhani, MD, and Janice Espinola, MPH, from MGH; Tristram Ingham, MBChB, Kristin Wickens, PhD, and Julian Crane, FRACP, from University of Otaga, Wellington, New Zealand; Karen Silvers, PhD, Michael Epton, PhD, FRACP, and Philip Pattemore, MD, FRACP, from University of Otago, Christchurch, NZ; and Ian Town, DM, from University of Canterbury, Christchurch, NZ. The study was supported by grants from the Health Research Council of New Zealand, the David and Cassie Anderson Bequest and the MGH Center for D-receptor Activation Research.
A dietary supplement of the synthetic derivative of vitamin B1 has the potential to prevent heart disease caused by diabetes, according to new research from the University of Bristol, funded by Diabetes UK. Vitamin B1 may help the body to dispose of toxins and therefore protect cells of the heart from becoming damaged.
Diabetes leaves the heart more vulnerable to stress as less oxygen and nutrients are delivered to the heart and other organs. Heart damage can be caused by high levels of glucose entering cardiovascular cells, which forms toxins that accelerate the ageing of the cell. Around 50 per cent of people with diabetes die from cardiovascular disease, and this complication is the leading cause of death among people with diabetes. Researchers warn that with increasing prevalence of diabetes ( around one in twenty people in the UK are now diagnosed with the condition ), diabetes will result in a new epidemic of heart failure unless new treatments are developed.
A team of researchers at the University of Bristol gave a synthetic derivative of vitamin B1 called benfotiamine to mice with and without diabetes. They found that treating mice with Type 1 or Type 2 diabetes with benfotiamine from the early stages of diabetes can delay progression to heart failure. They also found that the vitamin B1 derivative improved survival and healing after heart attacks in Type 1 mice ( and even in the mice without diabetes too ). Foods rich in vitamin B1 include Marmite, yeast and quorn, but it is not yet known whether changes to diet alone would provide enough of the vitamin to see the same effects as supplements achieved in mice.
Previous Diabetes UK-funded research at the University of Warwick was the first to show that people with Type 1 and Type 2 diabetes have around 75 per cent lower levels of vitamin B1 than people without diabetes. It is thought that this may not be due to diet, but due to the rate at which the vitamin is cleared from the body. Small scale clinical trials of people with Type 2 diabetes have also discovered a link between taking vitamin B1 supplements and a reduction in the signs of kidney disease.
The latest research has been published in the Journal of Molecular and Cellular Cardiology. Professor Paolo Madeddu who led this research at the University of Bristol said “Supplementation with benfotiamine from early stages of diabetes improved the survival and healing of the hearts of diabetic mice that have had heart attacks, and helped prevent cardiovascular disease in mice with both Type 1 and Type 2 diabetes. We conclude that benfotiamine could be a novel treatment for people with diabetes, and the next step in this research will be testing whether similar effects are seen in humans.”
Dr Victoria King, Head of Research at Diabetes UK said “Diabetes UK is pleased to have supported this research and is encouraged by these promising results which now need to be tested and confirmed in human trials. We would like to note that it’s still too early to draw any firm conclusions about the role of vitamin B1 in the prevention of complications and we would not advise that people look to vitamin supplements to reduce their risk of cardiovascular complications at this stage. Taking your prescribed medication, eating a healthy balanced diet and taking regular physical activity are key to good diabetes management and therefore reducing your risk of diabetes associated complications.”
Benfotiamine improves functional recovery of the infarcted heart via activation of pro-survival G6PD/Akt signaling pathway and modulation of neurohormonal response by Rajesh Katare, Andrea Caporali, Costanza Emanueli, Paolo Madeddu in the Journal of Molecular and Cellular Cardiology.
“It may be that the amount of omega-3 fatty acids in fish oil supplements are higher than most people would typically get from their diet,” White said.
However, White cautioned against gleaning any recommendations from the results of one study.
“Without confirming studies specifically addressing this,” she said, “we should not draw any conclusions about a causal relationship.”
Edward Giovannucci, M.D., Sc.D., professor of nutrition and epidemiology at the Harvard School of Public Health and an editorial board member of Cancer Epidemiology, Biomarkers & Prevention, agreed.
“It is very rare that a single study should be used to make a broad recommendation,” said Giovannucci. “Over a period of time, as the studies confirm each other, we can start to make recommendations.”
Still, fish oil continues to excite many, as evidence emerges about its protective effect on cardiovascular disease and now cancer.
Harvard researchers are currently enrolling patients for the randomized Vitamin D and Omega-3 Trial (also called VITAL), which will assess the impact of fish oil supplements and vitamin D on cancer, heart disease and stroke.
The researchers plan to enroll 20,000 U.S. men aged 60 years and older and women aged 65 years and older who do not have a history of these diseases and have never taken supplements.
The prospective Rotterdam Study involved 5,395 people over age 55 with no dementia at baseline. All of the participants, who lived in one section of the Rotterdam area, provided dietary information when the study began in 1990.
The researchers previously reported a similar association of vitamin E intake with a lower risk of dementia and Alzheimer's disease over six years of follow-up among the cohort.
The current study found that after 9.6 years of follow-up, 465 of the participants had developed dementia; 365 of these cases were classified as Alzheimer's disease.
Higher baseline vitamin E consumption correlated with lower long-term risk of dementia in models minimally adjusted for age only and those adjusted for age, education, apolipoprotein genotype, total caloric intake, alcohol and smoking habits, body mass index, and use of supplements (both P=0.02 for trend).
Dietary surveys indicated that margarine was by far the biggest contributor to vitamin E intake at 43.4%, followed by sunflower oil at 18.5%, butter at 3.8%, and cooking fats at 3.4%.
Participants with vitamin E intakes in the top third, averaging 18.5 mg per day, were 25% less likely to develop dementia of any kind over almost 10 years of follow-up than those in the bottom third, who averaged only 9.0 mg per day. Higher baseline vitamin E consumption correlated with lower long-term risk of dementia (both P=0.02 for trend).
While the top versus bottom tertile comparison was significant, the middle group with vitamin E intake averaging 13.5 mg per day was no less likely to develop dementia than the lowest intake group.
For Alzheimer's disease alone, the multivariate-adjusted risk was 26% lower among those with the highest intake compared with the lowest (95% confidence interval 3% to 44%, P=0.03 for trend). But intermediate intake again appeared to have no impact.
Other antioxidants — vitamin C, beta-carotene, and flavonoids — held no significant associations with dementia or Alzheimer's disease risk (multivariate adjusted P=0.50 to >0.99 for trend).
Sensitivity analyses excluding participants who reported taking supplements at baseline showed similar results.
The researchers noted that the vitamin intakes seen in the study were consistent with a typical Western diet but cautioned about the possibility of residual confounding in the observational results.
In most women folate, a type of B vitamin, reduces the risk of breast cancer. However, in women with a certain genetic make-up it has shown to be the opposite: folate raises the risk of breast cancer.
“Therefore I think it is too soon to introduce a general fortification of foodstuffs with folic acid”, says nutrition researcher Ulrika Ericson of Lund University.
Neither does she think it is a good idea to take multivitamin tablets and other dietary supplements containing folic acid (the synthetic form of folate) without special reason.
“It is better to eat a diet containing a lot of fruit, vegetables, legumes and wholemeal products. Then you get sufficient quantities of the natural form of folate, other vitamins and dietary fibre.”
In her doctoral thesis, Ulrika Ericson has taken as her starting point the major study from the 1990s, Malmö Diet and Cancer, which gathered information and blood samples from over 17 000 women. At the end of 2004, just over 500 of these women had developed breast cancer. Folate levels, genetic make-up and food habits in the breast cancer patients have then been compared with the corresponding data from the healthy women.
Those women whose intake of folate corresponded to the level recommended in Sweden had only half as great a risk of getting breast cancer as those who had the lowest intake of folate. This was the overall finding, which shows that folate generally protects against breast cancer. However, the breast cancer risk increased in line with folate levels for a specific sub-group among the women – those who had inherited a certain variant of an enzyme that affects how folate is used in the body.
The ten per cent of the women who had inherited this variant from both of their parents had the highest risk of breast cancer, particularly if they also took vitamin tablets containing folic acid.
“No-one knows which genetic variant of this enzyme they have. This is why I think people should only take dietary supplements if there is a particular reason to do so, not just because 'it's probably a good idea'”, says Ulrika Ericson.
She considers that there are two groups who could have a particular reason to take a folic acid supplement. These are people with a certain type of anaemia and low folate levels and women who are trying to become pregnant (folate reduces the risk of neural tube defects in babies).
To be on the safe side, others should avoid vitamin tablets containing folic acid while it is still unclear what the link is between folate and different types of cancer. Mandatory folic acid fortification of foodstuffs, which has been discussed in many countries including Sweden, is not appropriate in the current situation, according to Ulrika Ericson.
Food-specific diets rely on the myth that some foods have special properties that can cause weight loss or gain. But no food can. These diets don't teach healthful eating habits; therefore, you won't stick with them. Sooner or later, you'll have a taste for something else – anything that is not among the foods you've been “allowed” on the diet.
The popular high-protein, low-carbohydrate diets are based on the idea that carbohydrates are bad,
that many people are “allergic” to them or are insulin-resistant, and therefore gain weight when they eat them. The truth is that people are eating more total calories and getting less physical activity, and that is the real reason they are gaining weight. These high-protein, low-carbohydrate diets tend to be low in calcium and fiber, as well as healthy phytochemicals (plant chemicals).
Some authors of these fad diets advise taking vitamin-mineral supplements to replace lost nutrients. However, supplements should “bridge the gap” in healthy eating and not be used as a replacement for nutrient-rich foods. Also, the authors of high-protein, low-carbohydrate diets advocate taking advantage of ketosis to accelerate weight loss. Ketosis is an abnormal body process that occurs during starvation due to lack of carbohydrate. Ketosis can cause fatigue, constipation, nausea, and vomiting. Potential long-term side effects of ketosis include heart disease, bone loss, and kidney damage.
Successful weight loss (losing weight and keeping it off for at least five years) is accomplished by making positive changes to both eating habits and physical activity patterns.
How can you spot a fad diet?
Weight-loss advice comes in literally hundreds of disguises. Most often the “new” and “revolutionary” diets are really old fad diets making an encore appearance. Examples of fad diets include those that:
- tout or ban a specific food or food group
- suggest that food can change body chemistry
- blame specific hormones for weight problems
Ten Red Flags That Signal Bad Nutrition Advice:
- Recommendations that promise a quick fix
- Dire warnings of dangers from a single product or regimen
- Claims that sound too good to be true
- Simplistic conclusions drawn from a complex study
- Recommendations based on a single study
- Dramatic statements that are refuted by reputable scientific organizations
- Lists of “good” and “bad” foods
- Recommendations made to help sell a product
- Recommendations based on studies published without peer review
- Recommendations from studies that ignore differences among individuals or groups
Source: American Dietetic Association
Led by researchers at Copenhagen University in Denmark, Robbins and an international team of colleagues analyzed the results of seven large clinical trials from around the world to assess the effectiveness of vitamin D alone or with calcium in reducing fractures among people averaging 70 years or older. The researchers could not identify any significant effects for people who only take vitamin D supplements.
Among the clinical trial results analyzed was Robbins' WHI research, which was part of a 15-year, national program to address the most common causes of death, disability and poor quality of life in postmenopausal women such as cardiovascular disease, cancer and osteoporosis. Those trials were primarily designed to study the effect of calcium and vitamin D supplementation in preventing hip fractures, with a secondary objective of testing the supplements on spine and other types of fractures, as well as on colorectal cancer. The results were published in the Feb. 16, 2006 edition of the New England Journal of Medicine.
Fractures are a major cause of disability, loss of independence and death for older people. The injuries are often the result of osteoporosis, or porous bone, a disease characterized by low bone mass and bone fragility. The National Osteoporosis Foundation estimates that about 10 million Americans have osteoporosis; 80 percent of them are women. Four of 10 women over age 50 will experience a fracture of the hip, spine or wrist in their lifetime, and osteoporosis-related fractures were responsible for an estimated $19 billion in health-related costs in 2005.
“This study supports a growing consensus that combined calcium and vitamin D is more effective than vitamin D alone in reducing a variety of fractures,” said Robbins. “Interestingly, this combination of supplements benefits both women and men of all ages, which is not something we fully expected to find. We now need to investigate the best dosage, duration and optimal way for people to take it.”
Patients who use vitamin supplements also showed lower levels of plasma homocysteine than in patients who did not (P = 0.001) or healthy controls (P = 0.003). Vitamin B6 and folate were both associated with homocysteine levels, whereas vitamin B12 was not. Twenty-four (48%) of 50 controls and 23 (50%) of 46 of the celiac disease patients carried the MTHFR thermolabile variant T-allele (P = 0.89).
The research team concludes that Homocysteine levels are dependent on Marsh classification and the regular use of B-vitamin supplements reduces of homocysteine levels in patients with celiac disease.The study confirms earlier studies suggesting that both the presence and severity of celiac disease determined homocysteine levels.
The regular use of supplemental B vitamins resulted in higher levels of serum vitamin B6, folate, vitamin B12 and lower levels of plasma homocysteine in patients with celiac disease. Moreover, supplemental B vitamins seem to offer protection against the effects of villous atrophy on homocysteine levels, independent of the genetic susceptibility status as determined by carriage of the C677T polymorphism of 5,10 methylenetetrahydrofolate reductase.
World J Gastroenterol. 2009;15:955–960
Kidney stones are small, hard deposits of minerals and salts that can form in the kidneys when urine becomes concentrated. Specific treatment beyond increasing water intake is usually not needed, but a kidney stone can be very painful to pass, as anyone who has had one can tell you. While anyone can get kidney stones, there are multiple risk factors that can potentially increase your chances of acquiring them, including:
- Family history of kidney stones.
- Being over 40 years old.
- Being male.
- High protein, high sodium and high sugar diets.
- Being obese.
- Digestive diseases such as inflammatory bowel disease or surgeries such as gastric bypass.
You can reduce your risk of getting kidney stones by:
- Drinking water throughout the day. For those with a history of kidney stones, doctors usually recommend passing approximately 2.5 litres of urine daily. In summer months you need to consume considerably more fluids to stay well-hydrated.
- Eating fewer foods containing high amounts of oxalate. Kidney stones can form due to a build up of calcium oxalate. Foods rich in oxalate include spinach, beets, rhubarb, okra, tea, chocolate and soy products.
- Limiting salt and animal protein in your diet. Reduce the amount of salt in your diet and choose non-animal protein sources such as nuts to reduce your chances of getting kidney stones.
- Watching out for stealth sources of sodium. Some energy and sports drinks contain high levels of sodium and/or caffeine. While they may quench your thirst, you may also be increasing your risk of stone formation.
- Re-hydrating often if engaged in strenuous activity if you have long-term exposure to the heat. Painters, roofers, landscapers, marathon runners and people who enjoy outdoor sports activities that last several hours at a time need to pay special attention to their water intake and watch for signs of dehydration. Health experts recommend at least 16 to 32 ounces of water per hour of heat exposure. A lack of sweat or urination, dizziness, weakness, headache, muscle cramps, nausea or vomiting are possible signs of heat-related illness or dehydration.
- Avoiding calcium supplements, but calcium-rich foods are OK. Calcium in the food you eat does not increase your risk of getting kidney stones. Keep eating calcium-rich foods unless your doctor advises you otherwise. However, calcium supplements have been linked to higher risk of kidney stones. Consult your physician before starting a calcium supplement.
A dietitian like Nastaran can help those at risk to plan meals that will reduce the chance of getting kidney stones.