don't trust your naturopath

fifth daily cuppa for eighty-seven-year-old Beryl

Recently a friend visited a naturopath. Iridology. Don’t know much about iridology. He said something about her thyroid, or her adrenal glands or something being dysfunctional, and that she needs lots of magnesium. He also said she has to cut down on her tea-drinking. It seems to me that naturopaths like to target little indulgences, such as tea and coffee. Gluten’s another favourite, though I suspect there’s more justice in that one.

People say coffee and tea damage the kidneys. This one was thrown at me the other day again, so I’ve decided to check some of these claims out – bearing in mind that New Scientist and other respected science journals have given coffee a more or less clean bill of health.

The first site that came up, upon googling ‘coffee health’, was this one from Harvard Medical School. Apparently the September issue of Harvard Women's Health Watch weighs the pros and cons of coffee drinking, and again finds no problems for moderate coffee drinkers. But what is moderate coffee drinking? I often exaggerate my coffee drinking habits to annoy certain people around me who have a negative attitude to the stuff, but the fact is that I probably drink on average around four cups a day – a large cafetière-full. The article says:

For those who drink coffee to stay alert, new research suggests that you'll stay more alert, particularly if you are fighting sleep deprivation, if you spread your coffee consumption over the course of the day. For instance, if you usually drink 16 ounces in the morning, try consuming a 2-3 ounce serving every hour or so. Again, moderation is the key.

On the basis of these remarks, it’s surely fair to say I’m a moderate coffee drinker. I also do largely what they say here, I spread my consumption thinly through the day.

The benefits of coffee drinking are highlighted:

The latest research has not only confirmed that moderate coffee consumption doesn't cause harm, it's also uncovered possible benefits. Studies show that the risk for type 2 diabetes is lower among regular coffee drinkers than among those who don't drink it. Also, coffee may reduce the risk of developing gallstones, discourage the development of colon cancer, improve cognitive function, reduce the risk of liver damage in people at high risk for liver disease, and reduce the risk of Parkinson's disease. Coffee has also been shown to improve endurance performance in long-duration physical activities.

There are some down-sides though:

However, as the September issue notes, coffee is not completely innocent. Caffeine, coffee's main ingredient is a mild addictive stimulant. And coffee does have modest cardiovascular effects such as increased heart rate, increased blood pressure, and occasional irregular heartbeat that should be considered.

No mention is made of the kidneys. So I googled ‘coffee kidneys’ and this site came up first. The Coffee Science Information Centre looks to me like a bonafide science site, check it for yourself. They examine a range of tests and studies relating to three problems pertaining to kidney function: diuresis, detrusor instability [basically, urinary incontinence] and kidney stones.

The findings are that with high coffee intake you get more pissing, though moderate coffee drinking produces no appreciable effect. Though it’s often claimed that caffeinated beverages can cause dehydration and electrolyte loss especially in active persons and athletes, no studies have proven this. A survey of nine studies of the effects of caffeinated beverages concluded that ‘The scientific literature suggests that athletes and recreational enthusiasts will not incur detrimental fluid-electrolyte imbalances if they consume caffeinated beverages in moderation and eat a typical U.S. diet’.

A very large study of Norwegian women found that coffee consumption wasn’t significantly associated with urinary incontinence. This confirmed a number of earlier, smaller studies.

The most interesting section though, was that dealing with kidney stones. High fluid intake has long been used as a treatment for kidney stones, but recent research suggests that the composition of the fluid also matters, and that coffee consumption in particular lowers the risk of developing kidney stones.

I was intending to go to a lot of sites, but I feel that this is unnecessary – these two sites are convincing enough, and they reveal all their sources. The findings are easy enough to check.

And so to tea. Clearly it’s another caffeinated beverage and would have related effects, but it’s probably more touted for its health benefits even than coffee. The about.com site, for one, points out that tea is ‘packed with antioxidants’. Antioxidants are good for you, apparently, because they prevent the cellular damage caused by oxidation. Oxidation involves free radicals – charged atoms or molecules – seeking to re-establish stability by filching electrons from cells. Anti-oxidants provide free radicals with electrons so that presumably they go away happy and don’t try to damage or wear out or age our bodies. The type of antioxidants provided by tea are called phenols – also found in red wine methinks.

This BBC news piece from August last year cites research evidence that tea doesn’t dehydrate people, as some were wont to believe:

Tea not only rehydrates as well as water does, but it can also protect against heart disease and some cancers, UK nutritionists found. Experts believe flavonoids are the key ingredient in tea that promote health. These polyphenol antioxidants are found in many foods and plants, including tea leaves, and have been shown to help prevent cell damage.

This stuff about dehydration is quite important to me as well-wishers often tell me I should drink more water, but not in the form of coffee, as it dehydrates. The author of the BBC reported study [though she was only looking at tea] describes this as an urban myth. It should be noted though that that the Tea Council provided funding for the work.