Tuesday, June 24, 2008

Lead in Our Food? Now THAT's a Heavy Meal!

by Ladd McNamara, M.D.

Lead, a mineral for which the body has no use, is naturally found in the earth; in rocks, soil, rivers, lakes, seawater, and even the dust in the air. It has no taste or smell. It is the heaviest of all non-radioactive metals. It is found in virtually everything you eat, drink, and breathe. In a perfect world we would not be exposed to lead at all. In a perfect world there would be no lead in our food, water, or air. However, though we should minimize lead consumption, there will always be a background level of lead that naturally exists. Therefore, the real questions are how much is too much; i.e., how much is toxic, and what can we do about it?

For over 2500 years humans have worked with lead; made utensils, cups, plates and weapons with lead. The real contamination of our planet occurred during the 20th Century with the use of coal, leaded gasoline, metal work (brass and steel), lead paint, production and (improper) disposal of batteries, lead plumbing carrying our drinking water, lead from solder used to seal the seams of cans containing food, leaded pottery, and leaded glassware.

From 1920 to 2000, over 300 million tons of lead was mined and distributed in our environment. It was distributed throughout the atmosphere via combustion, burning of fossil fuels (coal), burning rubber, metal and battery production factories, etc., and has settled as a coating on the entire surface of the earth, land and sea. Tetraethyl and tetramethyl lead placed in gasoline began in 1923, with billions of tons of lead released into the atmosphere from car and truck exhaust. Lead-based gasoline was phased out in 1971 in the U.S. and most other countries. Some countries have lowered the levels of lead in gasoline, while other countries (particlularly in Africa) still use leaded gasoline with impunity.

Over the last three decades the U.S. and many other countries have been slowly cleaning up lead contamination mostly by banning its use. Dangerous areas of lead are mostly limited to soil and air around mines, landfills, old city lands, and manufacturing facilities producing batteries, recycling plants, and munitions.

Children under the age of 5 are most susceptible to lead because they put objects in their mouths, such as toys (and even dirt itself) that have been on the floor or ground. Prior to 1951, lead was used in paint in the United States, and children swallowing paint chips, or soil filled with microscopic paint chips from homes painted with lead-based paint caused permanent neurological problems, leading to today’s concern about lead. In a clean environment, a child putting toys that have been on the ground into their mouths would not be a problem. Yet, eating dirt should be discouraged because dirt and soil have 10 to 100 times the amount of lead than what is found in food. (Sorry folks, Dr. McNamara says the "three-second rule" does not apply, for many reasons. That is, food that is on the ground or in the dirt for three-seconds is considered "untainted" by some, but that's a fallacy, not only due to lead, but also from bacteria.)
I guess, I should first describe a few designations for measuring lead content. One is the proportion of lead to all other components in any material, …in terms of parts per million (ppm). One part per million corresponds to 1 milligram per gram (1/1000 of a gram), or one microgram per gram (1/1,000,000) of material. The other major measurement of lead is the total amount present, in grams or micrograms, depending on the amount present.

We eat, drink, and breathe lead every day. The majority of lead entering our body is from food. We can reduce it, but we cannot escape it. We also eliminate lead everyday; in our feces (lead that is ingested but not absorbed), in urine, sweat, hair, skin, nails, and via the gall bladder through the breakdown of hemoglobin that binds to lead. Usually the amount going in our bodies equals the amount going out. If we have more lead entering our body than we can eliminate then it can build to toxic levels. Lead is found throughout the body, in the blood, soft tissues, but mostly lead accumulates in the bones. Ninety percent of the lead in our bodies is found in our bones. The human body contains lead …the question is, how much is dangerous? The answer is the level that may cause cancer, miscarriages, or neurotoxicity in children.

As the environment has been cleaned up, the amount of lead in our food and water has declined. In controlled drinking water (safe levels), the level of lead is currently limited in the U.S. to 0.015 ppm (0.010 in California). That’s water; but most foods (particularly grains) cannot get to such low levels. Plants take up the lead from the soil. Most of the lead in our diet comes from plants (fruits, vegetables, and grains …particularly whole grains), and less so from meat.
The World Health Organization established the “tolerable weekly intake” level for lead obtained from food at 1.5 mg (1500 micrograms), corresponding to a daily lead intake of just over 0.2 mg (200 micrograms). Although many parts of the world have not yet met these standards, most first-world countries have.

In the U.S., current lead levels found in food range from 0.1 ppm to 0.3 ppm. This amount of lead is not thought to cause much harm, and certainly the lower the better. The average American adult that consumes about 1 kg of food (the average daily intake), with a lead level of 0.1 to 0.3 ppm in “clean food,” consumes between 0.1 to 0.3 mg (or 100 to 300 micrograms) per day. (In the future, “acceptable levels” of lead that is consumed daily will be lowered to less than 50 micrograms per day, ...less for pregnant woman, and less still for children ...but these lower levels can only be attained as the environment is cleaned up.) In the meanwhile, the more fruits, vegetables, and whole grains, the more the lead consumed. The more junk food and sugary beverages one consumes the less lead is consumed, however, the health risk is greater for sugar and processed flour than it is for the amount of lead obtained from eating whole grains, fruits, and vegetables. In other words, you're better off eating fruit, vegetables, and whole grains even though that is your greatest source of lead, than you are consuming high-glycemic, processed foods.

For those who eat healthy, particularly whole grains (fiberous, low-glycemic foods, whether in drink formulations or not), the good news is the body can eliminate the amount of lead that is consumed each day, preventing lead from concentrating and causing harm. There is a certain level of lead that is always in the body, but this does not mean that it is enough to cause disease and disorders. Only high lead exposure leads to neurological problems in children, miscarriages in pregnant women, and high blood pressure in adults.

Smoking cigarettes is a concerning source of lead. Five hundred micrograms of lead is found in each inhalation of cigarettes, and 1000 micrograms of lead is contained in one pack of cigarettes. (Most of it is immediately exhaled, but a concerning amount is obviously getting absorbed through the lungs.)

Avoid eating foods grown by the roadside, or grown in gardens near older homes, as these soils are generally more contaminated with lead than other soils. Even the cleanest soil still has lead in it, and that lead is taken up by plants. In particular, whole grain foods contain more lead than meat protein, beverages, and especially water. We need whole grains for a healthy diet, but along with whole grains comes more lead. BUT, is it dangerous to eat whole grains, fruit and vegetables? No, not grains grown in “safe soils.”

What about meal replacement drinks? It is the same as food. If there is more fiber, i.e., low-glycemic carbohydrates, then there would naturally be more lead than beverages made with simple sugars (and no fiber). If there is less fiber, and high-glycemic (simple) sugars then less lead would be present; possibly below the ability to test for its presence (but it would still be present). The drink that contained all high-glycemic sugary carbohydrates (and no fiber) is most likely to cause fat production and oxidative damage through spiking of insulin levels. However, which is better, to obtain harmless levels of lead (less than 100 micrograms per day) by consuming low-glycemic, high-fiber foods, or to eat a poor diet with high-glycemic foods? High-glycemic foods cause weight gain and oxidative damage. Other than smoking, obesity and high-glycemic foods are the biggest contributors to nearly every major chronic degenerative disease today. Our true enemy in our food is not the lead, but the combination of calories, trans fats, and refined, simple sugars.

Now that you understand that there is generally a “non-harmful” background level of lead in all foods, do NOT stop eating fruits, vegetables, and grains (except those grown in contaminated soils) and low-glycemic, high fiber meal replacement drinks. For example, even IF a particular healthy meal replacement drink were to contain 6 to 7 micrograms of lead per serving, and if that person were to consume that drink two to three times per day, for a daily total of 14 to 21 micrograms, that is still FAR LOWER lead consumption than the average 100 to 300 micrograms per day of lead obtained in the average American diet.

It is important to understand, consuming such a meal replacement drink would thereby be protecting you from consuming higher amounts of lead that you would eat from your regular foods.

The really good news is that you can further reduce your absorption of lead through the consumption of specific supplements. Calcium and vitamin C, to name just two nutrients, block the absorption of lead in your intestines. So, make sure you take a quality, balanced, pharmaceutical-grade supplement with healthy levels of calcium (with at least 1000 mg per day) and vitamin C (at least 1000 mg/day).

Ladd McNamara,M.D.