Q: I drink several cups of green tea every day for the health benefits. I prefer it with a little milk, but I've heard that milk proteins might interfere with polyphenol absorption. Is this true? Would the same apply to hot chocolate made with milk?
A: Polyphenols called catechins are the antioxidant compounds found in tea that confer its well-known health benefits. They're present in all types of true tea (from the plant Camellia sinensis). Catechin content is the highest in white tea, the least processed type. Green tea has the next highest catechin content, then oolong and, finally, black tea.
If you add milk to your tea, the milk protein, casein, binds catechins, making them unavailable to the body. German researchers recently focused on this effect in a small study which included 16 postmenopausal women who first drank black tea without milk.
The investigators found that the tea improved the ability of arteries to relax and expand, increasing blood flow. But when skim milk was added to the tea, this healthy effect was blocked. They also looked at how tea alone and tea with added milk affected blood vessels in rats and observed the same effects seen in the women.
Not surprisingly, this study got a lot of attention in England, a nation of tea drinkers, most of whom take their tea with milk. The findings may explain why the lower rates of heart disease and cancer seen in Asians (who traditionally don't add milk to tea) haven't shown up in the United Kingdom.
Like tea, cocoa is rich in polyphenols but of a different chemical class. A study published in the April 2007 Journal of Food Science found that milk proteins don't reduce the bioavailability of the polyphenols found in cocoa. The reasons for the difference in milk's effects on polyphenols in tea and cocoa aren't completely understood.
I don't imagine the tea-drinking Brits are going to change their ways and give up adding milk to their tea, but if you really want the health benefits of green tea, you should try to develop a taste for it without milk.
Q: I have a tendency to faint when I have blood tests and when I hear about medical procedures. What do these fainting episodes mean for my general health? Are there any supplements that can help?
A: This type of fainting, which may be an inherited tendency, is called vasovagal syncope and is an overreaction on the part of your involuntary nervous system to some stimulus - in this case, an impending blood test or medical procedure. Some people faint in response to the sight of blood or to an emotional upset. Other common causes of fainting include standing for a long period of time and exposure to heat or crowds or both.
Some people faint in association with anxiety attacks, strenuous coughing or even urinating. In your case, anxiety about a blood test sets off an exaggerated nervous system response - your heart rate and blood pressure drop, decreasing the flow of blood to the brain and leading to the fainting episode, which is the body's way of protecting the brain from lack of blood. No doubt you usually recover quickly, within seconds or just a few minutes.
Although fainting can also be a symptom of some serious medical conditions (heart disease, diabetes or a brain problem), the type of fainting you describe has no implications for your general health.
Some people experience warning symptoms before fainting, such as weakness, lightheadedness, nausea, yawning, sweating, feeling warm or rapid breathing. If you sense that a fainting spell is coming on, lie down and put your legs up (this allows blood to keep flowing to your brain), or sit down and put your head between your knees. Lying down for blood tests may not prevent you from fainting, but at least it will prevent a fall.
I know of no supplements that can help you overcome this tendency. But you may be able to avoid episodes via mind/body work such as relaxation techniques or hypnosis. Breathing techniques in particular may help you address an exaggerated response to situations that activate this part of your nervous system. The 4-7-8 Relaxing Breath that I teach will help you (visit www.DrWeil.com for step-by-step instructions).