A closer look at the Alkaline diets and products that tout health benefits. (Bigstock/Bigstock)

Lose a pound a day! Relieve your indigestion! Look younger! Cure cancer!

Scour the Internet and you’ll see a slew of Web sites promising to improve your health if only you follow their alkaline diet, drink alkaline water or buy a water ionizer to get it from your tap. But the evidence supporting any of the health claims for alkaline products is murky at best. Here’s what you need to know about this health fad.

The claim

The main idea put forth by marketers of alkaline products is that many people have an imbalance of acid in their body because of what they claim are acid-producing foods such as meat and processed goods. Raising our alkaline levels to neutralize that acid will foster better health, the argument goes. Some alkaline products feature a number of health claims, including greater weight loss, slowing down aging and preventing such diseases as cancer, diabetes and osteoporosis.

Measured on the pH (power of hydrogen) scale, a substance is considered alkaline if it has a pH above 7, acidic if it has a pH below that, and neutral when it is exactly at 7. For example, distilled water has a pH of 7, lemon juice is measured at about 2, and baking soda is about 9.

The reality

“The modern diet does produce slightly acidic urine,” says Tanis Fenton, a registered dietitian, epidemiologist and adjunct assistant professor at the University of Calgary in Alberta. Some researchers speculate that compared with early humans, our diets are more acid-producing as well as richer in saturated fat, simple sugars, sodium and chloride, and lower in magnesium and potassium. But even with a high acid load, Fenton says, research shows that the body does not become acidic. “Rather, the urine becomes acidic,” she says, “showing that kidneys are effective at excreting the acid.”

The human body has a range of pH values that span a full spectrum of levels, roughly from 2 to 8. The idea that you need to neutralize acid in your body by regulating your pH level — and that you should drink alkaline water to do so — is “not based on credible science,” says Joy Dubost, a registered dietitian and spokeswoman for the Academy of Nutrition and Dietetics. “The body can maintain the proper pH independent of diet,” she adds. And drinking alkaline water will do no more than wet your whistle, since water’s pH has no effect on the blood or the body’s cells, Dubost says.

For her doctoral work, Fenton was on a team that reviewed 238 studies for evidence linking an alkaline diet to bone health. Its findings, published in 2011 in the Nutrition Journal, concluded that there was no evidence that an alkaline diet improves bone health. Another study by Fenton and a colleague — a systematic review, not yet published, of the effects of an alkaline diet on cancer — found no benefits in the prevention or treatment of that disease.

The products

There are many ways that alkaline water and alkaline-style diets are marketed to consumers. Some health-food stores carry the water, and alkaline-ionized bottled water is sold online. Do-it-yourself water ionizer machines, which claim to convert tap water into alkaline water, are also sold online. The devices can cost several hundred dollars to more than $1,000.

There are also books about alkaline-rich diets, such as “The pH Miracle for Weight Loss: Balance Your Body Chemistry, Achieve Your Ideal Weight.” It emphasizes eating green vegetables and drinking alkaline water, and recommends taking supplements such as pH “drops,” according to a review by the Academy of Nutrition and Dietetics. The group concluded that the diet “is not a healthy way to lose weight.”

So far, the Food and Drug Administration has rejected certain health claims made by alkaline products. As for the diets, Dubost agrees with their emphasis on fruit and vegetables but cautions against restrictions on dairy and meat, which supply needed calcium, protein and Vitamin D.

She also warns that people who take medication for a major medical condition should consult a doctor before using alkaline products or starting an alkaline diet. That’s especially important for those who have kidney disease, because the phosphorus, potassium and sodium of alkaline products can build up to dangerous levels.

Bottom line

Drinking more water is a good idea for better health, but be wary of products that can suck your money down the drain.

Copyright 2013. Consumers Union of United States Inc.