Low-acid eating 101
Curious about how a low-acid diet may prevent bone loss? So were we. Here’s what the experts say about the theory—and why it’s still controversial
What’s the first thing that comes to mind when you think about maintaining strong and healthy bones? If you’re like many Canadians, the answer is probably calcium.
Calcium intake has long been the number one recommendation when it comes to preventing osteoporosis through nutrition. Medical professionals and associations such as Osteoporosis Canada promote calcium as the most important aspect of bone health.
But now, some researchers argue that endorsing calcium intake alone may not be the best way to prevent osteoporosis. Their claim: it's low-acid eating that will preserve your bones.
What is low-acid eating?
Proponents of the low-acid diet, a diet rich in fruits and vegetables, argue that when you eat foods that elevate the acidity level of your blood (primarily meat and other animal products), the body essentially pulls calcium out of the bones in order to neutralize that acidity and bring the blood's pH back to optimal levels. “When that happens, the calcium gets shunted out through the urine,” says Amy Joy Lanou, an assistant professor of health and wellness at the University of North Carolina and co-author of the book Building Bone Vitality (McGraw Hill, 2009). As you may have guessed, peeing out calcium can weaken your bones.
According to Lanou, a food can be considered “low-acid” when it is low in amino acids and high in minerals such as potassium and magnesium. “The reason fruits and vegetables are low-acid is because they don’t have very much of the acid-forming material, the amino acids, and they have lots of the minerals that are important for bone health,” she explains. Meats and animal products, on the other hand, are high in amino acids.
How low-acid eating works
In a study published in the January 2009 issue of The Journal of Clinical Endochonology and Metabolism, researchers gave bicarbonate (a chemical that keeps the blood pH neutral) supplements to older adults and found that they excreted less calcium in their urine. Their conclusion: increasing the alkali content of the diet could help prevent bone loss.
“Each time you eat an acid-forming meal, like turkey and provolone on white bread, it increases the acidity in your blood a little bit,” says Lanou. That small increase causes the body to try to return your blood to a neutral pH by drawing calcium from your bones. However, eating fruits and vegetables preserves bones by helping your body keep acidity levels at neutral.
While it hasn’t yet been proven that eating a low-acid diet can completely prevent or reverse bone loss (genetics is also a risk factor for osteoporosis), Lanou says it can help slow bone loss and strengthen bones.
The argument against focusing on calcium
In Building Bone Vitality, Lanou and co-author Michael Castleman point to studies showing that countries that consume the most calcium (North American and European countries among them) have the highest rates of fractures caused by osteoporosis, while countries that consume the least amount of the mineral (Asian countries) have the lowest rates. If calcium-rich diets were the key to preventing fractures caused by osteoporosis, the results would be the opposite, they argue.
The reason for this discrepancy, says Lanou, is that bone density or the amount of minerals (such as calcium) in the diet isn’t the only factor affecting bone health. “The fracture studies go against the notion that adding calcium to the system benefits bones,” she says. However, she adds that consuming calcium in and of itself isn’t the problem and does recommend getting about 500 to 700 mg daily (a much lower amount than the 1,000 mg recommended by Osteoporosis Canada for women under 50). “Our argument is that we focus so much on calcium that we’ve missed the point, and the point is that we need to be eating an overall dietary pattern that supports bone, instead of focusing on that single nutrient,” she says.
Why the low-acid eating theory is controversial
While most medical professionals would agree that a diet rich in fruits and vegetables is beneficial for your overall health, some experts aren’t convinced that following a low-acid diet alone is enough to prevent osteoporosis. “I think there’s something there, but it has to be qualified,” says Susan Whiting, a nutrition consultant for Osteoporosis Canada and a University of Saskatchewan professor who conducted a study that couldn’t prove the theory that a high-acid diet can cause the body to draw calcium from the bone. She stresses that low-acid eating comes third or fourth on the list of important things you should do to keep your bones strong. “First, you want to make sure you have enough calcium and vitamin D,” she advises, “and you do want to have enough protein. We really need protein to make bone, so it’s not a good idea to slam it.”
The low-acid diet theory remains controversial, suggests Whiting, because groups that have political anti-milk or anti-meat agendas often promote it. However, she argues that it’s not only animal protein that causes acidity in the blood, but all protein, including soy. “[Osteoporosis Canada doesn’t] promote the low-acid diet specifically because we promote having a good diet, which includes fruits and vegetables,” she stresses.
What to eat to keep your acid levels low
If you do decide to aim for a lower-acid diet, it’s as simple as adding more fruits and vegetables to every meal. And you don’t have to completely eliminate animal protein from your diet to maintain good bone health, says Lanou. Remember the turkey and provolone sandwich that increased your body’s acidity levels? Simply replace the provolone with lettuce and tomato and add a minestrone soup to the meal to provide the alkaline substances that can neutralize that acidity without drawing calcium from bone, she says.
Need advice on how to add more veggies to your diet? Try these tips:
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Web exclusive: March 2010