David L. Katz, MD, a professor at Yale University and author of The Flavor Point Diet, sorts out the healthy, the harmful, and the hype.

I’ve read that drinking red wine benefits the heart. Does 100 percent red grape juice have the same healthy effect?

With grape juice, you’d be missing out on wine’s alcohol, which in moderation raises protective HDL cholesterol, makes platelets less apt to stick to one another, and increases a chemical in the body that helps dissolve blood clots (it’s called tPA – tissue plasminogen activator – and is actually used as a drug to treat heart attacks and strokes in emergency rooms).

But I don’t recommend you start drinking alcohol just for your heart.

Both wine and 100 percent grape juice, especially the dark purple Concord variety, have another ingredient with cardiovascular benefits: flavonoids – antioxidants that are concentrated in the skin of grapes.

You can also get flavonoids from coffee, dark chocolate, fruits, vegetables, and green tea. So if red wine isn’t your cup of tea, have the grape juice. Or, for that matter, the tea.

I read that the stress hormone cortisol can prevent you from losing weight. Is there anything I can take to help?

A number of products with names like Relacore, CortiDrene, and CortiSlim promise to help you lose weight by lowering either stress or cortisol levels. But I am not convinced that any of them safely and reliably alter cortisol or even cause weight loss.

Evidence does suggest that chronically high levels of cortisol may cause fat to accumulate around the middle and make weight more difficult to lose (in addition to triggering other adverse health effects).

But I worry about any pill that would oppose cortisol. Hormones have far-reaching effects, and shutting off one could wreak havoc with many aspects of normal metabolism.

The better approach is to address the problem at the source: Although you can’t eliminate stress from your life, you can keep it from damaging your health.

Yoga, meditation, breathing techniques, and regular physical activity all help dissipate stress and keep the body from producing undesirable levels of cortisol. Think of it this way: It’s far more effective to prevent the fire than to dress in asbestos.

Does Reducol really lower cholesterol levels? Are there any side effects?

Reducol is the trade name for a patented blend of sterols and stanols – natural, fatlike compounds derived from the oils of coniferous trees and used in margarine spreads and supplements.

Because sterols and stanols mimic cholesterol, they fool the body into thinking it has eaten too much of the lipid. This results in more cholesterol being passed through the intestines, which in turn means lower levels in the blood.

The reduction is generally modestly to 15 percent with the recommended intake of two to three grams a day.

But a study published in the Journal of the American Medical Association in 2003, by David Jenkins, MD, and colleagues, showed that sterols could be about as effective as the most popular anticholesterol drugs, statins, if they’re part of an ultrastrict lipid-lowering diet.

The FDA has accorded Reducol “generally recognized as safe” status, and I am unaware of any reports showing adverse effects.

(Statins, on the other hand, can cause liver toxicity, although they are recommended for most patients with very high cholesterol because a rigid diet like Jenkins’s is too hard to follow.)

There are, however, theoretical dangers of sterols and stanols:

excessively low cholesterol – an essential compound in the right amounts – which could cause impaired libido, depression, and possibly increased susceptibility to infection; interference with the production of sex hormones like estrogen that are made from cholesterol; and depletion of fat-soluble vitamins such as A, D, E, and K.

In general, if you stick with trusted brands, I think taking Reducol is safe and reasonable. [via]