DEAR DR. BLONZ: A nutritionist doctor suggested a commercial baking yeast (Red Star Yeast) to lower my cholesterol. I have not wanted to go on statins, and was happy to try this widely available product. I know that everything has a side effect, and was hoping that you could discuss the side effects and efficacy of this choice. I am concerned, in particular, by the fact that I am experiencing bloating. -- S.P., San Jose, California

DEAR S.P.: The commercial baking yeast you mention is NOT associated with lowering elevated blood cholesterol levels, and is probably not the “yeast” you had been told to take. Let me explain.

Yeasts are single-cell microscopic organisms that can grow with or without oxygen. The common baking yeast (Saccharomyces cerevisiae) is an active yeast that uses oxygen and consumes carbohydrates (flour and simple sugars), creating energy for growth and producing carbon dioxide as a byproduct. The addition of small amounts of the appropriate yeast to baked goods results in gas production, which causes the food to rise during the baking process. If this is what you are taking, that is very likely the cause of the bloating you are experiencing.

Other types of active yeasts are used in beer brewing and winemaking. There are subtle differences. Such yeasts can grow without oxygen, which causes the organisms to produce alcohol as a byproduct. In a carefully controlled process, the gas that is produced can be captured to make beer and sparkling wines.

Brewer’s yeast, however, is an inactive yeast that is the same organism. It is sold as a dietary supplement and can be a source of certain nutrients, especially the B vitamins. There are also nutritional yeasts, such as torula yeast and whey yeast, which are organisms cultivated specifically for use as nutritional supplements. Vegemite and Marmite are yeast extracts sold as nutrient-rich dietary supplements.

I don’t know the credentials of this individual, but I am wondering if they might have actually recommended “red yeast rice.” Different from the above, this is a rice product that has been fermented with the yeast organism Monascus purpureus, also called “red yeast.” This yeast organism produces monacolin K, a substance that is associated with an ability to decrease cholesterol production by the human body. It does this by slowing down the activity of a key liver enzyme involved in cholesterol synthesis.

Be advised that the monacolin K in red yeast rice is actually a statin. It is the same one found in lovastatin, a commonly prescribed drug for high cholesterol. It can be effective when taken as prescribed by your physician. As with other statins, there can be side effects and interactions with other medications. There are also issues about taking certain statin substances along with grapefruit juice (see tinyurl.com/ybasfccf). Read more about red yeast rice and monacolin K (lovastatin) at tinyurl.com/ycbkw7nu.

Red yeast rice is sold as a dietary supplement, and there may be issues of quality control; seek assurances that all products, and every pill, has the same level of active ingredients. It is also essential to inform your health professionals if this is something that you are taking or considering.

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 is your advice regarding spray dietary supplements? I am also interested in dietary supplement foot pads, which are promoted for detox and weight loss. Are these safe and effective, as the ads promise? I would appreciate your opinion. -- M.C., San Jose, California

DEAR M.C.: Dietary supplements are substances taken orally; in other words, there is a swallow involved. The substances are regulated as foods, not drugs. Read the “FDA 101: Dietary Supplements” at tinyurl.com/yaaugh5f for a larger perspective.

Dietary supplements, by definition, are a category of food intended for ingestion as a tablet, capsule, powder, softgel or liquid. The “spray vitamins” I am aware of involve spraying a mist into your mouth, followed by a pause -- ostensibly for the active ingredients to be passively absorbed (in theory) through the highly vascular tissues in your cheeks, under the tongue and elsewhere in the mouth.

If we stopped there, this would not fit the regulatory definition of a dietary supplement. Simply put, there has to be a swallow somewhere in the process. To skirt this issue, spray products often include instructions to swallow after use. Absent this inclusion, there is a risk of a regulatory “knock on the door” at some point. Irrespective of regulations, it cannot be assumed that any spray product’s active ingredients will make it into the body when the product is used as directed.

The topic of drug delivery through the tissues in the mouth has been discussed in scientific literature. There have been studies showing that small amounts of vitamin B-12 can be absorbed through the vascular membranes in the mouth and nose, which would have some application for individuals who have problems with B-12 absorption, but any advantage for others is questionable. Only certain types of compounds can pass through oral membranes. The science here is rather heady, but there is an application with certain types of pharmaceuticals: Oral absorption can be facilitated by additives designed to assist with the process, but these artificial, nonfood compounds are not allowed in dietary supplements.

The bottom line is that mouth and cheek tissue can serve as a portal for certain substances, but it is far from an open-door policy.

As for foot pads, there is obviously no “swallow” involved, so these are not even dietary supplements. They are a drug or a medical device, and unapproved at that. Such products cannot legally bear a “Supplement Facts” label. I could find no evidence that these types of products are effective with “detox,” weight loss or any medical condition.

Consumer protection organizations, including the Federal Trade Commission and attorneys general of the states, have acted to stop the marketing and sale of such products. The fact that you might see them for sale should not be taken as an indication of their efficacy or legality.

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 actually controls how much cholesterol the body makes? Can the body manufacture more cholesterol than it gets in food? -- D.D., Philadelphia

DEAR D.D.: Cholesterol is an essential structural element in every cell of the body. It is also a raw material for many hormones, including estrogen and testosterone. Given these points, you would wonder how vegans survive -- without eating animal products, they have no source of dietary cholesterol.

The answer is that the body does, indeed, make cholesterol on its own. It is a waxy substance and, like other lipids, does not dissolve in our body’s water-based blood. As a result, it needs to be shuttled around the blood inside fat-carrying proteins called lipoproteins.

Most of the body’s cholesterol is manufactured in the liver. When cholesterol is present in the foods we eat, the liver is programmed to make less. There are a number of genetic conditions in which the body makes more cholesterol than it needs, but they are rare. More common is the condition in which a person has an unbalanced diet heavy in meat, fat and simple carbohydrates, and light on whole grains, greens, fresh fruits and vegetables. Couple this with an inactive, stress-filled lifestyle, and elevated blood cholesterol comes knocking at the door.

This is a concern for many, so I encourage you to read more on the topic at tinyurl.com/ya489wua and tinyurl.com/ycu2s63m.

DEAR DR. BLONZ: At least once a day, three fingers on my right hand turn white, then purple. They feel tingly and usually become numb. My doctor has never seen it happen. He has not known how to approach the situation, so it gets ignored. What do you think it could be? Is it related to allergies or anything I am eating? I’m a 78-year-old woman in otherwise great health, but this is quite annoying. -- L.E., via email

DEAR L.E.: I need to remind you up-front that I am not a medical doctor, so I cannot diagnose your problem or dispense medical advice. But I can say that your issue is not likely to be related to nutrition. The National Institute of Health has information about a condition known as Raynaud’s phenomenon at tinyurl.com/y7wm4rcv. I would recommend that you read this and determine if it fits your situation.

Then -- and this is most important -- make an appointment to discuss the issue with your physician. You can take the information from the NIH (or not, if it doesn’t apply). If you don’t get the attention you need from your current health professional, seek another. Your health is on the line, and you should not be ignored.

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.