DEAR DR. BLONZ: I am concerned about using aluminum cookware and foil, as they present a danger of aluminum leaching into my food and causing health problems like Alzheimer's or autism. -- H.G., Chicago

DEAR H.G.: Are we in some danger zone where we must avoid using aluminum cookware and even aluminum foil? First things first: Any suggestion that aluminum exposure through our food can cause serious health issues like Alzheimer's, autism, dementia or cancer is not based on known facts.

Let's address this oft-aired concern with a bit of rigor, covering the following: 1. the amount of aluminum naturally present in foods; 2. how efficiently the aluminum we ingest is absorbed (its bioavailability); 3. the established safety tolerance for aluminum, and 4. what would be the weekly intake of aluminum if all foods were cooked in aluminum cookware, stored in aluminum containers and wrapped using aluminum foil. How would that level of exposure compare with the established safety tolerance limits?

Let's address those points in order:

1. Aluminum is the third-most abundant of all elements in the Earth's crust and is naturally present in foods. You cannot avoid exposure, whether your food is organic or conventionally grown. The daily intake of naturally present aluminum is about 3 milligrams per day, and processed foods and medications containing aluminum additives can add to that total. Another concern, of course, would be for any exposures at work or where one lives, but that is a separate issue.

2. The aluminum in our food has minimal bioavailability; less than one-tenth of 1% (0.01%) of ingested aluminum gets absorbed, most passing in the feces. Any absorbed will get handled by the kidneys, so those with impaired kidney function will be at greater risk.

3. Safe levels of aluminum intake for most individuals, referred to as the upper safety tolerances, have been established by various agencies and vary by age, sex and health status. The Environmental Protection Agency has its reference dose set at 1 milligram per kilogram of body weight per day. The joint U.N./World Health Organization expert committee came up with similar findings. This level equates to a safety tolerance of about 3.2 milligrams of aluminum for every pound of body weight per week. For a 150-pound individual, the safety tolerance would be 480 mg of aluminum per week.

4. The classic study published in the journal Food Additives and Contaminants (Jan./Feb. 1995) reported that if you were to take an entire week's food supply, store it in aluminum containers, prepare it in aluminum cookware and wrap it in foil, the total aluminum intake from these exposures would be approximately 42 milligrams of additional aluminum per week. Even after adding the aluminum naturally present in the food, you would still be at about one-tenth of the tolerable limit.

These numbers tell the story that the levels of aluminum in the food -- and that which would be added if one were to use aluminum cookware, containers and foil -- are well below the level at which any harm would be anticipated.

Finally, never lose sight of the message that an active lifestyle complemented by a whole-food, plant-based (not necessarily vegan) diet facilitates our overall health in so many ways -- one of which is to keep systems involved with disposing of unwanteds like aluminum on their game.

Send questions to: "On Nutrition," Ed Blonz, c/o Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to questions@blonz.com. Due to the volume of mail, personal replies cannot be provided.

DEAR DR. BLONZ: You, and other experts, always say to "wash your fruits and vegetables." But I haven't seen much about what that really means: Splash them with water? Run water over them for an amount of time? Do the rules change for produce sprayed with pesticides, or for members of the so-called "dirty dozen"? Should any be washed with dish soap, or is water sufficient?

I heard once that fruits and vegetables should be scrubbed as well as rinsed. That seems to make sense for veggies like potatoes, which have relatively hard surfaces, but what about delicate fruits such as raspberries and blueberries?

How about a one-time primer on what exactly "washing" fruits and vegetables means? -- A.F.

DEAR A.F.: Produce has lots of opportunities to pick up unwanted elements: from the soil, or from various local animals, while it is growing; at the store where it is stored and sold; and even in your vehicle on the way home. Doing a wash at home helps remove any contaminants hitchhiking on your wholesome foods. This is even more important for children, the elderly or anyone with an ailment or condition that might weaken the immune system.

I worked in the produce department at a local supermarket while in high school, getting fresh fruits and vegetables ready for customers and removing any produce past its prime. Fruits and vegetables are usually washed before being packed, but the handling from field to store is always a bit of a wild card. There is nothing wrong with any added measure of cleanliness.

Wash produce with clean hands in a clean area -- one that is not used as a resting place for dishes waiting to be washed or other questionable items. Rinse items in cold, potable, running water for at least 15 seconds. Do this before the produce is sliced, as cutting can transfer unwanted elements from the surface into the flesh. (Cutting tools should also be freshly washed.)

If the flesh of the produce is eaten and not the peel -- think citrus, bananas, melons, avocado and pomegranates -- a wash of the outsides is prudent. A produce brush can provide extra abrasion, but ensure it, too, gets cleaned and is allowed to dry between uses.

Regarding delicate fruits, I typically have berries with my breakfast. After purchase, I give them a cold soak for several minutes, gently agitating with a clean hand, followed by a generous rinse in a colander. I then transfer them to a container with a good-fitting lid.

Fruits and vegetables are not waterproof, of course, and can absorb liquids to varying degrees. Any fluid you use to wash your vegetables should be approved for food use; dishwashing detergents, for example, are not generally advised.

Here are three resources for additional information: 1. The CDC page on produce safety at b.link/Mzzrww; 2. The FDA's seven tips for cleaning fruits and vegetables at b.link/rnx3n4; and 3. The National Pesticide Information page on washing when there are concerns about pesticide residues at b.link/pjvqdd.

Send questions to: "On Nutrition," Ed Blonz, c/o Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to questions@blonz.com. Due to the volume of mail, personal replies cannot be provided.

DEAR DR. BLONZ: A natural health practitioner was a guest at a recent dinner engagement. She declined the water offered, saying that drinking water with or immediately after the meal dilutes the enzymes and gastric juices meant for digestion, causing digestive problems. This became a lively topic of discussion at the table. She also mentioned that those who drink water might face the consequence of abnormal weight gain because the undigested food can start to rot in the system, producing toxins and belly fat, resulting in obesity. That was shocking to hear, and most went silent. I wanted to check this out before I mention this to the host who held the dinner, as she is a client of the practitioner, who, she had told me, has a widespread practice. -- S.F., Los Angeles

DEAR S.F.: Let's calm any notion that a glass of water with a meal is risky business. There is no evidence -- it's nonsense! -- that water will mess with digestion and create rot and toxins in the body.

Our secretions of digestive juices are based on the type of foods consumed; these get released at points of the digestive tract to perform specific actions on foods. Digestive enzymes break apart complex substances into smaller pieces on the way to being made available for absorption. Key here is the understanding that adding water does not change the amount of the substances in need of enzymatic breakdown -- water does not "dilute" enzymatic action. Water can facilitate mixing and contact between an enzyme and its targets. Also important to consider is that water requires no digestion, being effectively absorbed in the stomach and at other points.

Our stomach does release acid to help denature proteins as a first step to breakdown; that acid also helps destroy pathogenic organisms. The release of acid is governed by the need to establish a pH correct for the type and amount of food needing that digestive action. Acid sufficient to have the needed effect will get released; that, along with water absorption, helps maintain the needed pH while food is being processed in the stomach.

The other rather silly assertion relates to indigestion. No question that indigestion can give rise to discomfort, as incompletely digested foods can end up in places where they are not welcome, causing bloating, cramping and other forms of distress. But this indicates the food and its calories have not been processed and absorbed.

It's hard to see the purported connection between obesity and increased belly fat with the inefficient digestion of food and absorption of its calories. The mention of the production of toxins and "rot in the system" stemming from that water is also a bit wacko. My compliments for your skepticism.

Send questions to: "On Nutrition," Ed Blonz, c/o Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to questions@blonz.com. Due to the volume of mail, personal replies cannot be provided.