New evaluation of acid/alkaline food load

[Guest guest]

(this goes beyond the ash analysis technique that most charts of

acid/alkaline foods are grouped by, and instead measures the potential

renal acid load. - D.E.)

 

From http://www.t-mag.com/nation_articles/269cov2.html

 

Acid-Base Nutrition Basics

By John M Berardi

 

When a food is ingested, digested, and absorbed, each component of that

food will present itself to the kidneys as either an acid-forming compound

or a base-forming one. And when the sum total of all the acid producing and

the base producing micro and macronutrients is tabulated (at the end of a

meal or at the end of a day), we're left with a calculated acid-base load.

If the diet provides more acidic components, it will obviously manifest as

a net-acid load on the body. And if it provides more basic components, it

will obviously manifest as a net-base load on the body.

 

In the past, scientists have looked for various techniques to try to

quantify whether a food is acid producing or base producing. One method

that was commonly used was ash analysis. Using this technique, a food would

be combusted and the ash would be analyzed to determine how much of the

food was alkaline and how much was acid. When examining the micronutrients

present in many foods we see that:

 

* Acidic anions in food include chloride, phosphorous, sulfates, and other

organic acids.

 

* Basic/Alkaline cations in food include sodium, potassium, calcium, and

magnesium.

 

The ash analysis technique has its limitations, though. Since simple

food/ash analysis doesn't take into account bioavailability of the

nutrients in a given food, the acid-base balance of the body after

consuming specific foods doesn't often match the acid or base-producing

estimate generated from the ash analysis. In other words, the ash analysis

ain't all that effective.

 

Recognizing this limitation, Remer and Manz developed food-rating values

that they refer to as PRAL (potential renal acid load) and the NAE (net

acid excretion).(1) The NAE can be determined directly by measuring the

acid and the ammonium appearing in the urine and then subtracting out the

measured urinary bicarbonate. This method yields a net acid excretion score

based on direct measurements of the urine. This score, however, reflects

total acid and base load of a mixed diet and not the acid or base load of

the individual foods in the diet.

 

To more accurately predict the acid or base potential of a given food,

another technique is needed. Unlike the aforementioned technique, the NAE

can be determined indirectly by adding up all the urinary acidic anions

from the above method and subtracting out the basic/alkaline cations

described above. Since the urinary anion and cation excretion is directly

related to food intake, it's possible to approximate net acid or base load

from the composition of the food. This net acid or base load is called the

PRAL (potential renal acid load).

 

Therefore, in taking into account the composition of the food, the

bioavailability of the different micro and macronutrients (especially

protein) of the food, the sulfur content of the food, and the obligatory

diet-independent organic acid losses, it's then possible to estimate a

physiologically meaningful index of the acid or base load based on the food

consumed (PRAL).

 

For those of you who don't really care about PRALs and NAEs, here's the one

sentence summary of what I'm talking about. In layman's terms, researchers

can now analyze a food and based on its components, determine what the true

acid or base load on the body will be. If you're still wondering why this

is important, read on.

 

 

Why Acid Is Bad

 

Every cell of the body functions optimally within a certain pH range (pH is

a measure of the acidity or alkalinity of the body). In different cells,

this optimal range is different, however, the net pH of the body has to

remain tightly regulated. One common problem with most industrialized

societies is that our diets produce what's called a " low grade chronic

metabolic acidosis. " In other words, the PRAL of our diets is high and this

means that we're chronically in a state of high acidity. While there are a

number of disease states that induce severe metabolic acidosis, we're

talking a sub-clinical rise in acidity here. Therefore, your doc probably

won't notice the problem. But that doesn't mean that you're in the clear.

Your cells will recognize the problem.

 

So what's wrong with this low-grade chronic metabolic acidosis? Well, since

the body must, at all costs, operate at a stable pH, any dietary acid load

has to be neutralized by one of a number of homeostatic base-producing

mechanisms. So, although the pH of the body is maintained and your doctor

visits turn out fine, many cells of the body will suffer. Here are some of

the most severe consequences of your body's attempt to maintain a constant

pH in the face of an acidic environment:

 

* Hypercalciuria (high concentrations of calcium in the urine). Since

calcium is a strong base and bone contains the body's largest calcium

store, metabolic acidosis causes a release in calcium from bone. As a

result, osteoclastic (bone degrading) activity increases and osteoblastic

(bone building) activity decreases. The net result of these changes is that

bone is lost in order to neutralize the acidic environment of the body. The

calcium that was stored in the bone is then lost in the urine along with

the acid it was mobilized to neutralize. This creates a negative calcium

balance (more calcium is lost from the body than is consumed) and bones get

weak. (2,3,4,6)

 

* Negative nitrogen balance (high concentrations of nitrogen in urine).

Glutamine is responsible for binding hydrogen ions to form ammonium. Since

hydrogen ions are acidic, glutamine acts much like calcium to neutralize

the body's acidosis. Since skeletal muscle contains the body's largest

glutamine store, metabolic acidosis causes muscle breakdown to liberate

glutamine from the muscle. The amino acids from this muscle breakdown are

then excreted, causing a net loss of muscle protein. (2,7)

 

In addition to bone and muscle loss, other consequences of acidosis include:

 

* Decreased IGF1 activity (4)

 

* GH resistance (4)

 

* Mild hypothyroidism (4)

 

* Hypercortisolemia (4,5)

 

Interestingly, low-grade metabolic acidosis seems to worsen with age. Many

have speculated that this is due to an age-related decline in kidney

function (and acid excretion). Of course, osteoporosis and muscle wasting

are unfortunate consequences of aging. While it's too early to tell,

perhaps some of the bone and muscle loss evident as individuals get older

is a result of diet-induced acidosis. This means that employing a few

simple acid-base strategies may help slow osteoporosis and sarcopoenia.

 

 

What's Wrong With Your Diet?

 

Recently, Sebastian and colleagues compared the pre-agricultural diet of

our ancestors to the modern North American diet.(8) After evaluating the

two diets for what they call NEAP (net endogenous acid production) -

essentially the same measure as the PRAL above a -88mEq/day acid load

characterized the pre-agricultural diet while the modern diet was

characterized by a +48mEq/day acid load. What this means is that our

ancestors evolved eating a diet that was very alkaline/basic and therefore

very low acid. However, modern people are eating a diet that is high in

acid, and therefore very different from what we evolved to eat. As a

result, our modern diet is responsible for what the authors have called a

" life-long, low grade pathogenically significant systemic acidosis. "

 

How have we gotten so far off track? Well, the shift from net base

producing foods to net acid producing foods comes mostly as a result of

displacing the high bicarbonate-yielding plants and fruits in the diet with

high acid grains. In addition, most of our modern energy dense, nutrient

poor selections are also acid forming. Finally, high protein animal foods

tend to be acid producing as well.

 

If you're now wondering how your diet stacks up, check out the table I've

provided below. This table includes a listing of 114 commonly consumed

foods and their PRAL scores. A negative PRAL score indicates the food is

basic/alkaline. A positive PRAL score indicates the food is acidic. A score

of 0 indicates the food is neutral.

 

 

*This table is adapted from the Remer and Manz study discussed above (1)

and each PRAL score is based on a 100g portion of food.

Food Group and Food

PRAL Score (mEq/day)

 

Meat and Meat Products Average :9.5

 

7.8 Lean Beef

8.7 Chicken

13.2 Canned, Corned Beef

6.7 Frankfurters

10.6 Liver Sausage

10.2 Lunch Meat

7.9 Lean Pork

8.8 Rump Steak

11.6 Salami

9.9 Turkey Meat

9.0 Veal Fillet

 

Fish Average: 7.9

 

7.1 Cod Fillet

6.8 Haddock

7.0 Herring

10.8 Trout

 

Milk, Dairy, and Eggs:

 

Milk and non-cheese average 1.0

Low protein cheese average 8.0

High protein cheese average 23.0

 

0.5 Buttermilk

16.4 Low Fat Cheddar

18.6 Gouda Cheese

8.7 Cottage Cheese

1.2 Sour Cream

8.2 Whole Egg

1.1 Egg White

23.4 Egg Yolk

19.2 Hard Cheese

0.6 Ice Cream

1.1 Whole milk

0.7 Whole Milk Pasteurized

34.2 Parmesan Cheese

28.7 Processed Cheese

1.2 Whole Milk Yogurt w/Fruit

1.5 Whole Milk Yogurt Plain

 

 

Sugar and Sweets Average: 4.3

 

2.4 Milk Chocolates

-0.3 Honey

3.7 Cake

-1.5 Marmalade

-0.1 White Sugar

 

Vegetables Average: -2.8

 

-0.4 Asparagus

-1.2 Broccoli

-4.9 Carrots

-4.0 Cauliflower

-5.2 Celery

-2.0 Chicory

-0.8 Cucumber

-3.4 Eggplant

-1.8 Leeks

-2.5 Lettuce

-1.4 Mushrooms

-1.5 Onions

-1.4 Peppers

-4.0 Potatoes

-3.7 Radishes

-14.0 Spinach

-2.8 Tomato Juice

-3.1 Tomatoes

-2.6 Zucchini

 

Fruits, Nuts, and Juices Average: -3.1

 

-2.2 Apple Juice

-2.2 Apples

-4.8 Apricots

-5.5 Bananas

-6.5 Black Currants

-3.6 Cherries

-1.0 Grape Juice

-2.8 Hazelnuts

-4.1 Kiwi Fruit

-2.5 Lemon Juice

-2.9 Orange Juice

-2.7 Oranges

-2.4 Peaches

+ 8.3 Peanuts

-2.9 Pears

-2.7 Pineapple

-21.0 Raisins

-2.2 Strawberries

+ 6.8 Walnuts

-1.9 Watermelon

 

 

Grain Products

 

Bread average: 3.5

Flour average: 7.0

Noodles average: 6.7

 

4.0 Mixed Grain Rye Bread

4.1 Rye Bread

3.8 Mixed Grain Wheat Bread

1.8 Wheat Bread

3.7 White Bread

6.0 Cornflakes

3.3 Rye Crackers

6.4 Egg Noodles

10.7 Oats

12.5 Brown Rice

1.7 White Rice

5.9 Rye Flour

6.5 White Spaghetti

7.3 Whole Grain Spaghetti

8.2 Wheat Flour

 

 

Legumes Average: 1.2

 

-3.1 Green Beans

3.5 Lentils

1.2 Peas

 

Fats and Oils Average: 0

 

0.6 Butter

-0.5 Margarine

0.0 Olive Oil

0.0 Sunflower Oil

 

 

Beverages

 

Alkali rich average: -1.7

Alkali poor average: 0

 

-0.2 Draft Beer

0.9 Pale Beer

-0.1 Stout Beer

0.4 Coca-Cola

-0.4 Cocoa

-1.4 Coffee

-1.8 Mineral Water

-2.4 Red Wine

-0.3 Tea

-1.2 White Wine

 

 

 

 

I'm Here To Straighten Out Your Acids

 

After perusing this list it should be apparent that both the typical modern

diet as well as the typical athletic diet is suspect. After all, even a

high protein diet rich in clean, whole grain carbs will produce a net acid

load. Since a neutralization of the Western diet without a change in energy

intake or macronutrient composition has been shown to improve bone health,

to shift nitrogen balance from negative to positive, to reduce blood

cortisol concentrations, to increase thyroid hormone production, and to

reverse the GH resistance discussed above, it's important that athletes

take the appropriate steps to shift their diets away from that low grade

chronic metabolic acidosis we discussed earlier. Here are some steps for

accomplishing this goal:

 

* Use the chart above to calculate a PRAL score for each meal. To do this,

you simply record the amount (in grams) of each food you eat in a meal.

Then, multiply the PRAL score listed by your food amount. For example, if

you've eaten 250g of lean meat (8 oz or about 1/2 lb), your PRAL score for

the meat will be 7.8 (score for 100g) multiplied by 2.5 (for the 250g

serving), or 19.5. If you've also eaten 250g of potato (8 oz or 1/2lb),

your PRAL score for the potato is -4 (score for 100g) multiplied by 2.5

(for the 250g serving) or -10. In addition, if you've eaten 100g of

spinach, the PRAL score for the spinach is -14. If you tally up the total

score of this meal, the net PRAL is 19.5 (meat), -10 (potato), -14

(spinach), or -4.5. This means a meal containing 8 oz of lean meat, 8 oz of

potato, and 3.5 oz of spinach produces a PRAL of -4.5. In other words, the

meal produces a net alkalinity. That's what we're looking for.

 

* After calculating the base or acid potential of the meal, add more

vegetables regardless of the final tally. Everyone can always benefit from

more vegetables in the diet. Many bone specialists are now recognizing that

the most effective way to improve bone health is to eat lots of fruits and

vegetables.(3)

 

* If you're eating a big meal that's going to be a net acid producer and

don't want to add more basic foods, consider adding a small amount of

glutamine to this meal. Exogenous glutamine supplementation has been shown

to neutralize acidosis.(7)

 

* A cheaper alternative to glutamine supplementation is either sodium or

potassium bicarbonate supplementation. You can add sodium bicarbonate (in

the form of baking soda) to your beverages including your protein shakes,

which probably are a bit on the acidic side (see milk above). A small 2-5g

dose of baking soda would be sufficient to neutralize the shake. An

alternative to baking soda is alka-seltzer.

 

* Adding sodium to foods can increase the base potential and reduce the

acidity of the meal.

 

 

A Few Additional Protein Notes

 

Many doctors, dietitians, and sports nutritionists have come down on animal

protein for several reasons including its effect on renal acid load. While

it's true that animal protein (especially animal flesh) does produce a high

PRAL, I find it interesting that the same " experts " espouse high grain

diets. As you can see from the charts above, whole grains are also very

acid forming.

 

Another interesting fact is that while a high protein diet is acid forming,

the high protein diet also seems to counteract some of its own acid loading

potential.(9) In other words, while protein produces an acid load, it also

increases the body's capacity for excreting those acids. None of the other

acid producing foods are as effective as protein in doing so. Besides, just

like with the other acid-forming foods, all you have to do is consume

enough basic foods and supplements to neutralize the acidity.

 

 

Conclusions

 

Just because very few individuals in the sports-nutrition world are talking

about acid-base balance doesn't mean that it's not important. Employing a

few simple strategies to neutralize your high-acid diet may mean the

difference between chronic low-grade acidosis - and the associated muscle

wasting, bone loss, and altered hormonal profile - and a healthy, alkaline

diet.

 

 

 

John M Berardi is a scientist and PhD candidate in the area of Exercise and

Nutritional Biochemistry at the University of Western Ontario, Canada. His

company Science Link: Translating Research into Results specializes in

providing integrated training, nutritional, and supplementation programs

for high-level strength and endurance athletes. For more information about

our team or our services, please visit JohnBerardi.com.

 

 

References

 

1) Remer and Manz, J. Am Diet Assoc. 95: 791-797, 1995.

 

2) Frassetto et al, J Clin Endocrinol Metab. 82: 254-259, 1997.

 

3) New, Proc Nutr Soc. 61(2): 151-164, 2002.

 

4) Wiederkehr et al, Swiss Med Wkly. 10:127-132, 2001.

 

5) Maurer et al, Am J Physiol Renal Physiol. 284(1): F32-40, 2003.

 

6) Buclin et al, Osteoporos Int. 12: 493-499, 2001.

 

7) Welbourne, et al. JPEN. 18(3): 243-7, 1994.

 

8) Sebastian et al. Am J Clin Nutr. 76(6): 1308-1316, 2002.

 

9) Remer et al, Eur J Nut. 40(5): 214-20, 2001.