In the News: Blueberries & Metabolic Syndrome, Cancer Risk & HDL, Caffeine & IOP

Healthful Blueberries: Bang for the Buck

Metabolic syndrome is a constellation of disorders that can raise the risk of developing diabetes and cardiovascular disease (CVD). High blood pressure, high triglycerides, abnormal cholesterol, obesity and lots of fat in the abdomen and waist area are among the associated problems. What’s alarming is that up to 25% of Americans are thought to fit the profile for metabolic syndrome, mostly due to the obesity epidemic we face.

Weight loss and exercise are our biggest weapons in the fight against metabolic syndrome. Results of a new study (1) now suggest that regularly eating blueberries can also help reduce some of the adverse health risks associated with this syndrome.

In the study, overweight people with the syndrome who consumed a beverage providing 50 g of freeze-dried blueberries daily for 8 weeks had greater decreases in their blood pressure and biomarkers for inflammation compared to people getting a placebo beverage. Oxidized LDL cholesterol in the blood, which can directly damage the lining of arteries, was also significantly decreased in the “blueberry” group.

Blueberries, like bilberries, are very high in polyphenols – compounds that are believed to be responsible for the berries’ heart-healthy benefits. The volunteers in this study consumed the equivalent of a little more than 12 ounces of blueberries daily – an amount that is fairly easy to achieve.

Higher HDL May Mean Lower Cancer Risk

According to an analysis of 24 randomized, controlled trials, HDL cholesterol (the so-called “good” cholesterol) might reduce the risk of cancer (2). The authors, from Tufts University, report that cancer risk dropped 36% for every 10 mg/dl increase in HDL.

It’s not understood how HDL might help combat cancer. One theory is that it could have antioxidant and anti-inflammatory effects. Or HDL may help the immune system search out and destroy abnormal cells with the potential of growing into tumors. The researchers point out that their study can’t prove that low HDL levels up the risk of cancer. However while we await further findings, it’s still a good idea to keep HDL levels as high as possible since it’s already known to help protect against heart disease. Optimum levels for cardio-protection are at least 60 mg/dl, with higher levels even better.

How can we boost HDL? Regular exercise, weight loss (for those overweight), and not smoking have the biggest impact on bolstering HDL levels. Moderate alcohol consumption has a modest effect, and omega-3 might be helpful as well. A recent study found an association between omega-3 intake and HDL, with a 2.5 mg/dl increase in HDL observed for every 1% increase in omega-3 consumption (3).

High Eye Pressure & Caffeine: Bad Combo?

Moderate coffee intake – about 2-3 cups daily or the caffeine equivalent of about 250 mg – appears to be safe for most people. At that level of intake, the bulk of the evidence indicates that caffeine isn’t cancer-causing, doesn’t cause or worsen CVD or hyper-tension, and doesn’t raise the risk of fibrocystic breast disease or bone loss. Caffeine may even have some benefits: it’s been linked to a lower risk of type-2 diabetes, gallstones in men, and Parkinson’s disease.

For people with glaucoma and elevated intraocular pressure (IOP) however, regular or excessive caffeine intake may not be a great idea. In an analysis of 6 trials, the IOP of normal individuals did not go up when measured 30, 60 and 90 minutes after ingesting caffeine (4). IOP did, however, rise significantly at these time points when people with glaucoma or ocular hypertension were given caffeine.

References

1. Basu A, et al. Blueberries decrease cardiovascular risk factors in obese men and women with metabolic syndrome. J Nutr 140:1582-87, 2010.
2. Jafri H, et al. Baseline and on-treatment high-density lipoprotein cholesterol and the risk of cancer in randomized controlled trials of lipid-altering therapy. J Am Coll Cardiol 55:2846-54, 2010.
3. Buyken AE, et al. Modifications in dietary fat quality are associated with changes in serum lipids of older adults independently of lipid medication. J Nutr 140:88-94, 2010.
4. Li M, et al. The effect of caffeine on intraocular pressure: a systematic review and meta-analysis. Graefes Arch Clin Exp Ophthalmol [Epub Aug 12, 2010]