DEAR DR. ROACH: Can you tell me about food poisoning? I often hear the term, but it seems to mean different things to different people. – VA

ANSWER: Foodborne illnesses are indeed a very large and diverse group. Although the term may refer to toxins in food, such as poisonous mushrooms or heavy metal contamination, it most often refers to illness caused by infectious pathogens, usually bacteria and viruses, but parasites as well.

The most common infectious foodborne illness is associated with what’s called a toxin-mediated diarrhea. Many bacteria, such as E. coli, can cause watery diarrhea that starts within a day or two of ingestion of a contaminated meal. Viruses, especially norovirus and similar, are very infectious and cause outbreaks in homes, institutions and cruise ships. Parasites, such as Giardia and Cryptosporidium, are often ingested through contaminated water and may cause longer-lasting symptoms. Most cases of watery diarrhea are self-limited and do not need treatment.

Some unhealthy bacteria grow in the intestine and cause diarrhea with fever and sometimes blood. There are four that may cause a fever 48-72 hours after ingestion: Salmonella, typically from undercooked eggs or poultry; Shigella, which is highly infectious and transmitted by poor hand hygiene and contaminated food; Campylobacter, also from undercooked poultry; and an especially nasty strain of E. coli called O157: H7, most associated with beef. Diarrhea with fever or blood may also go away on its own, but should still be evaluated by your medical provider since some of these causes can be quite serious.

Some foodborne illnesses cause vomiting, not diarrhea. The toxin from Staphylococcus aureus (“staph”), which often is triggered by dairy, eggs or salad that has been left at room temperature, causes vomiting about six hours after consumption of the food. Bacillus cereus, classically from fried or other rice that has sat out, also causes acute nausea and vomiting within a few hours. Since these toxins are heat-stable, reheating the food does not prevent it from causing symptoms.

Preventing foodborne illness depends on correct kitchen technique: Keep your food preparation surfaces and hands clean with frequent washing. Keep fish and meat separate from all other foods. Think of raw fish and raw meat as being contaminated until they are properly cooked. Cooking to the correct temperature will effectively kill the germs. Once cooked, consume or refrigerate promptly.

DEAR DR. ROACH: Every day I take a mixture of 15 vitamin and mineral supplements, including a multivitamin. They are all moderate doses. Do you think I am overdoing it and should eliminate some of the supplements? I am 81 years old and don’t want to have any overdose problems. – BR

ANSWER: Dietary supplements may be a good way of treating minor symptoms when the risk of a serious medical illness is small. For some conditions, dietary supplements have been shown to be helpful. However, many people take supplements when they are perfectly healthy to prevent disease, and despite many studies, there is no good evidence that they prevent illness or make people live longer.

There is the possibility of an interaction among some of your supplements, and possibly between the supplements and food or with any medication you may be taking. Look carefully at your supplements, think carefully about why you are taking them, and speak with your doctor or pharmacist about whether they are effective for what you want them to do.

Dosing of many medications, including supplements, may need to be reduced for a person in their 80s.

As always, I recommend taking supplements that have been independently verified by a third-party laboratory for content and purity whenever possible.

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Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to or send mail to 628 Virginia Dr., Orlando, FL 32803.

(c) 2021 North America Syndicate Inc.

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