Fruits and vegetables yield many health benefits, because they supply ample vitamins, minerals and fiber. But research suggests a plant-heavy diet may promote bone health, support digestion and help ward off disease, thanks to their chemistry. Unlike protein-rich, animal-sourced foods like pork roast, chicken and cheddar cheese, fruits and veggies don’t break down into acid in the body.
Sure, oranges, apples and asparagus have plenty of acid—but that’s not the issue. “A food can contain acid but not be acid-forming, and those that taste acidic aren’t usually problematic once in the stomach,” says Amy Joy Lanou, PhD, senior nutrition scientist for the Physicians Committee for Responsible Medicine and coauthor of Building Bone Vitality (McGraw-Hill, 2009). “When a food has been digested and its byproducts change the acidity of the blood, that’s where the problem starts.”
Blood is naturally slightly alkaline, with a pH hovering around 7.4 (zero is most acidic, 7 is neutral and 14 is most alkaline), which mirrors the acidity of a primitive hunter-gatherer diet. But some health experts claim that the introduction of dairy, meat, cereal grains and processed foods into the Western diet has made our overall food intake more acid-churning, which may in turn tilt the blood toward acidity.
How acid-forming foods affect health?
So how does even slightly acidic blood impact overall health? According to Lanou, the bones bear a significant brunt of this shift. In attempt to bring blood pH back into balance, the body pulls alkaline compounds, namely calcium carbonate, from the bones, thus depleting them of a vital component of their ongoing break-down-and-rebuild process. “Bones are not just alkaline storage sites,” she says. “They actively use alkaline compounds to regenerate, so when they’re pulled away, it hinders an important function.” Constant depletion can lower bone mineral density and increase osteoporosis risk.
Beyond skeletal health, highly acidic diets are thought to play a role in the prevalence of heart disease, diabetes and other serious illnesses common in Western societies. And while not life-threatening, acid reflux may have as much to do with acid-forming foods as untamed stomach acid shooting back up the esophagus. In a study published in Annals of Otology, Rhinology & Laryngology in May 2011, acid reflux suffers who hadn’t found relief with medication saw a sharp decrease in symptoms after following a strict low-acid diet for two weeks.
Some skeptics counter this whole concept, saying the body is naturally adept at balancing its pH levels. They’re correct in that the body would never let blood pH dip to deadly levels. But as Lanou and others believe, a steady stream of acid-forming foods requires a constant pulling of alkaline compounds, nutrients and energy away from other functions. Over time, they say, this will throw systems out of whack, overtax the body and make you more prone to disease.
What not to eat
According to Lanou, the top acid-producing culprits are meat, cheese and fish, but certain grains and nuts can create acid as well. And when it comes to meat, “leaner doesn’t mean less acid,” she says. “Fish is a little lower, but there isn’t much difference between chicken and red meat.” Processed foods are also troublesome because many of the preservatives added to extend shelf life are acid-forming.
Not only do fruits and veggies not churn up acid—equally as important, they break down into alkaline elements, which neutralize acid formed by other foods. Thus, they buffer the bones by giving the body something else to extract alkaline from.
“It takes five to seven cups of raw fruits and vegetable to neutralize the acidity of a turkey and cheese sandwich,” says Lanou, who suggests shooting for six to nine servings of produce per day. “It doesn’t matter so much which ones you choose, but where you can slip more into your diet. Can you add vegetables to your breakfast or you double your portion for dinner? Maybe trade out a serving of another kind of food.”
When eating any type of meat, Lanou stresses tempering the acid load by creatively combing it with veggies. “Mix meat right in with vegetables,” she says. “A 3-ounce chicken breast on top of a salad is much closer to neutral than a meal of chicken and bread. Go with a veggie-heavy chicken stir-fry instead of sweet-and-sour chicken with a few veggies on the side.”
Consider a vegetarian diet
Whether or not you’re on board with the acid-alkaline idea, the benefits of plant-heavy diets abound, so swapping portabellas for pork chops and green beans for garlic bread never hurts.