DEAR DR. BLONZ: I often see xanthan gum in the ingredients lists of salad dressings and chocolate syrup. There are other types of gums in processed foods as well. My naturopath said that if these are eaten, the gums can build up in the intestines and cause problems. Is that true? -- S.F., New York City

DEAR S.F.: Vegetable gums such as agar, locust bean gum, tragacanth, xanthan gum, and pectin are used as food additives to help with texture and spreadability, and provide a slippery “mouthfeel” such as the one generally associated with butter and similar products.

These compounds are built like a carbohydrate, but they’re constructed in a way that digestive enzymes cannot attack, which means they stay too large to be absorbed and won’t directly contribute calories. There is no evidence or reason to believe that gums build up and cause toxic reactions at the levels consumed as additives in foods. If the testing prior to their approval had revealed such evidence, they would have never been approved as additives. But gums can be acted upon by the flora in our large intestines, so there is a chance consuming them will produce brief, minor digestive effects, including gas and laxation.

You mentioned xanthan gum in particular, which is made from a specially fermented corn syrup, itself made from corn starch. It was created at a USDA research station in Peoria, Illinois, as part of a project to find new uses for surplus corn. Xanthan gum helps to thicken the texture of food, and it has proven to be quite versatile. Aside from syrups and salad dressings, it is found in puddings, sauces, baked goods and desserts. Because it is made from corn, xanthan gum should be avoided by individuals allergic to corn, but aside from that, there do not appear to be any problems associated with its use.

Use caution listening to advice from individuals who have a history of dubious statements.

DEAR DR. BLONZ: My question is whether adding a small bit of sugar -- say, a teaspoon or so -- changes the acidity of tomato sauce. My partner insists that is what happens, but I remain skeptical. If sugar caused this change, what would be the chemical reaction? -- S.T., Columbia, South Carolina

DEAR S.T.: Added sugar would help offset the dominance of the acid taste of a tomato, but it doesn’t react with or neutralize the acid in any significant way.

DEAR DR. BLONZ: I am soliciting your review of using Java tea for weight loss. One product says the tea contains natural fat-burning enzymes, and that these enzymes get absorbed and help release fat cells from storage areas. It says the tea also contains flavonoids that clean and unclog the large intestine’s mucous membranes, which, by themselves, can help you to lose 3 to 4 pounds within the first 48 hrs. Is there anything to this, or is it a myth and theoretical? -- R.P., Chicago

DEAR R.P.: While tea contains flavonoids, which are healthful phytochemicals, the rest is filed under “myth and theoretical.” Tea is a healthful beverage, but the bits about fat-burning enzymes and intestinal “mucous membrane cleansing” are nonsense.

Claims are easy to make, especially when you don’t back them up with objective evidence. Drink the tea if you enjoy it, but I wouldn’t waste my time or money if these claims are the only motivation.

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: What makes a vitamin water-soluble? I know vitamins A, D, E and K are not water-soluble, and that B and C are. Does this relate to the fact that we do not store water-soluble vitamins in our body? -- H.T., Phoenix

DEAR H.T.: First, some history about what we now call vitamins. The work of Louis Pasteur (1822-1895) and Robert Koch (1843-1910) revealed that germs were responsible for diseases. Scientists then began working to identify the bugs behind every illness. Sanitation was found to be a key, and the “germ theory” of disease ruled the day. Some ailments, however, were found to persist even when sanitation was under control. The concept that what we ate, or failed to eat, was involved was not widely embraced, but as time went on, scientists began to investigate the role of diet.

The usual way to establish the essentiality of a nutrient is through an investigation of what happens when it is absent. Because vitamins are present (and needed by the body) in relatively small amounts, it was not until researchers had an ability to purify foods that they could know what, precisely, was being fed. Answers began to emerge when experiments started using purified diets that only contained protein, fat and carbohydrate. These nutrients, by themselves, did not support life; young animals failed to grow, and mature animals failed to maintain their body weight. It became clear that there were other essential substances.

As analytical procedures progressed, the different essential micronutrients were discovered. The first of these nutrients contained the element nitrogen, in the form of an amino group. It was assumed that all micronutrients would have a similar structure, and this new group was referred to as “vital amines,” or “vitamines” -- a word coined in 1911 by a Polish scientist named Casimir Funk. It was later determined that not all of these substances were built in the same way, but the name -- shortened to “vitamins” -- had already become part of scientific jargon.

An adult is about 60% water by weight. Water gets consumed, serves as the medium for biochemical reactions, then serves as the vehicle to help eliminate metabolic byproducts through the kidneys. By contrast, the body conserves fat by virtue of its role as the body’s concentrated source of metabolic energy.

When the vitamin discoveries began, it became convenient to classify these substances by whether they dissolved in water or fat. This classification was not based on whether the vitamins were stored; that was not known at the time. This system, however, has remained. Due to the constant turnover of water through the body, water-soluble vitamins are not effectively stored to any appreciable degree. Fat-soluble vitamins tend to get distributed in body fat, so they hang around for a while.

The fat-soluble vitamins include A, D, E and K, as you mentioned. The water-soluble vitamins include thiamine (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), pyridoxine (B6), ascorbic acid (C), vitamin B12, folate, choline and biotin.

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: I need a bit more info about an ongoing internet campaign against canola oil. There is a claim that this oil was developed as a name-change alternative to rapeseed oil, after that oil was found to cause health problems. A place where I buy some of my food (and whose advice I sometimes follow) rails about its use in prepared foods. The claim is that it is toxic, especially when used in cooking, and that it is produced from genetically modified grain -- stealthily imported from Canada behind the back of the Food and Drug Administration.

I am hoping for your assessment as to whether there is anything scientifically valid here, or if this just ongoing nonsense. -- T.S., Topeka, Kansas

DEAR T.S.: This is an issue that seems to emerge periodically, with its lease on life recycled through the communicative and archive powers of the internet and social media. One difficulty is that many people who maintain sites with dubious information don’t take down the inaccuracies when confronted with solid evidence to the contrary. Conspiracies do make for compelling postings, but this one is already a bit rancid. I wish that people would give it up, because it is confusing well-meaning, health-conscious consumers.

Perhaps we can all do a little community service and have some facts at the ready to put this nonsense to rest. Rapeseed (Brassica napus) is a member of the mustard family. It is known for its oil-rich seeds that are used in animal and human food.

Traditional rapeseed contains a toxic fatty acid compound known as erucic acid. This was used in animal feed, but did not appear to be associated with any problems with animals who have multichambered stomachs. The fermentation vat in such digestive systems, known as the rumen, appears to be able to detoxify erucic acid. For animals with a one-chambered stomach, like us, traditional rapeseed oil -- with its elevated content of erucic acid -- is to be avoided.

In the 1970s, using traditional plant-breeding techniques -- not genetic engineering -- rapeseed was successfully bred to reduce its erucic acid content. The erucic acid was replaced during breeding with oleic acid, the healthful fatty acid found in olives and other plants.

The name “canola” was originally a trademark standing for “CANada Oil, Low Acid,” which was deemed a more palatable name than “low-erucic acid rapeseed oil.” (The low-acid plant was bred in Canada.) The canola plant is now a different variety of rapeseed; think of it as a distant, younger cousin to traditional rapeseed. Organically grown canola, available in the marketplace, is a testimony that this type of oil can have a non-GMO pedigree.

Similar to any cooking oil, as long as canola oil is not overheated or otherwise abused, it will not become toxic when used in cooking. The smoke point for canola oil is over 400 degrees F, which is high enough for most types of cooking.

Bottom line: Be wary of advice from sites that continue to spread misinformation.

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.