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In the News: Folic Acid & Hearing Loss, Meat & Heart Disease, B6 & Colon Health

Folic Acid May Help Preserve Hearing

Low blood levels of folate are associated with a 35% increased risk of hearing deficits, according to a recent study that strengthens the link between B vitamins and protection against hearing loss. Loss of hearing is the most common sensory disorder in the US, affecting more than 36 million people.

The Blue Mountains Hearing Study (1), based on a population of nearly 3,000 people aged 50+, found that low blood levels of folate (below 11 nanomoles per liter) correlated with a greater risk of age-related hearing loss. In addition, higher blood levels of the naturally occurring compound homocysteine (over 20 micro-moles per liter) were linked with a 64% higher risk. An elevated level of homocysteine may adversely affect blood flow in the inner ear, and studies have shown that levels of folic acid, as well as vitamins B6 and B12, can influence homocysteine concentration in the blood.

This is not the first time folic acid has been linked to the prevention of hearing loss. In 2007, researchers reported that folic acid supplements delayed age-related hearing loss in the low frequency range in a study of 700+ men and women 50-70 years of age (2).

In addition, Boston-based researchers have just reported that men over 60 with high folate intake from foods and supplements had a 21% lower risk of developing hearing loss (3). Scientists now need to conduct large trials to assess these associations.

Watch Your Intake of Processed Meats

The findings of a new review and meta-analysis (4) provide some good and bad news for meat lovers. Researchers from the Harvard School of Public Health looked at 20 prior studies that examined red and processed meat intake and the risk of coronary heart disease (CHD), stroke and type-2 diabetes. The analysis involved more than 1.2 million people from 10 different countries.

They found that eating processed meat is associated with a higher risk of CHD and diabetes, but that consumption of red meat such as beef, pork or lamb is not linked to these conditions.

Processed meats were defined as any meat preserved by smoking, curing, salting, or chemical preservatives. That includes meats such as bacon, sausage, salami, luncheon meats and hot dogs. In fact, eating just 1.8 ounces of processed meat per day (about 1 hot dog or 2 slices of salami) was associated with a 42% greater risk of CHD, and increased the risk of diabetes by 19%.

Prior studies did not separately evaluate unprocessed red versus processed meats, which may explain why these studies came up with conflicting results on the health effects of red meat. While we’ve tended to blame the saturated fat in red meats for heart disease, the results of the Harvard study suggest it might not be that simple. Processed and unprocessed red meats contain similar amounts of saturated fats and cholesterol, but the processed kind have about 4 times more sodium and 50% more nitrate preservatives. It may be that the salt and preservatives are more the culprits, rather than simply the fats.

Low B6 Levels Could Impact Colon Health

The results of a new Swedish study add to the mounting evidence that maintaining high blood levels of vitamin B6 may help reduce the risk of colorectal cancer (5). Researchers pooled and analyzed the results of 13 studies that examined the relationship between vitamin B6 and colorectal cancer. They found that people with the highest blood levels of the vitamin were less likely to develop the disease. When one study with inconsistencies was excluded, analysis of the remaining 12 studies showed a 48% reduction in risk for every 100 picomole per milliliter increase in blood levels of B6.

References

1. Gopinath, B et al. Serum homocysteine and folate concentrations are associated with prevalent age-related hearing loss. J Nutr 140(8):1469-74, 2010.
2. Durga J, et al. Effects of folic acid supplementation on hearing in older adults: a randomized, controlled trial. Annals of Intern Med 146:1-9, 2007
3. Shargorodsky J, et al. A prospective study of vitamin intake the risk of hearing loss in men. Otolaryngol Head Neck Surg 142:231-6, 2010.
4. Micha R, et al. Red and processed meat consumption and risk of incident coronary heart disease, stroke, and diabetes mellitus: a systematic review and meta-analysis.Circulation 121:2271-83, 2010.
5. Larsson SC, et al. Vitamin B6 and risk of colorectal cancer: a meta-analysis of prospective studies. JAMA 303:1077-83, 2010.