Dear Dr. Blonz: We are doing a project on nutrition labeling at school. I have noticed that fruits or foods (such as tuna) can be packed with a liquid that contains calories from sugar or oil. Does the listing of calories per serving include the calories from the liquid? If I drained most of the juice or oil off the food before eating it, approximately how many calories (or fat grams if appropriate) would be saved? Here's the info from a single-serving can of peaches: serving size 1 cup; calories: 120; total fat: 0 grams; sodium: 15 milligrams; potassium: 150 milligrams; total carbohydrates: 29 grams; fiber: 2 grams; sugars: 27 grams. Here is the ingredient list: peach slices, water, sugar, natural flavor, citric acid and ascorbic acid. -- B.T., Tulsa, Oklahoma

Dear B.T.: The Nutrition Facts panel describes the portion upon which the numbers are based. There may be brand-to-brand differences. If there is no statement that the nutrition information is based on drained contents, it should be assumed that the serving is a portion of the entire contents. In the example you provide, it would be the entire contents of the can, including the juice.

There is, of course, the option of draining the liquid to avoid some of the sugar calories. You can also decrease sugar and carbohydrate calories by using fresh fruits or fruits packed in water, rather than heavy syrup, or doing a fresh-water rinse of fruits packed with the syrup. With tuna, a similar goal would be achieved by draining the oil, but there will always be some oil left. (Be aware that the oil used in canned tuna is usually vegetable oil, not the omega-3-rich oil found in tuna.) You can select a brand of tuna that is packed in water.

Although not in the case you cite, products often list the nutritional value of the drained contents. For your project, consider creating a table that lists the nutrition facts between similar serving sizes of drained fruit from different liquids. By comparing the same portion from brands packed in light syrup, juice and heavy syrup, and comparing these with one packed in water, you can see the number and type of calories the accompanying liquid leaves behind after draining. For tuna, you can do this with the drained oil-pack vs. water-pack cans.

Dear Dr. Blonz: I read an article written by a respected scientist who said that that dairy foods and beef contain trans fatty acids naturally. I had thought that they were the result of hydrogenation or high processing temperatures. -- W.P., Sun City, Arizona

Dear WP: Small amounts of trans fatty acids can be formed by the bacteria that normally live in the rumen of the digestive system of cattle. (The rumen is the part of the bovine digestive system that helps break down the grasses, shrubs and grains consumed by the cow.) These are different from the ones formed during the commercial process of partial hydrogenation of vegetable oils. There is no evidence that the naturally formed trans fats represent a health risk, especially given the small amount present.

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: Usually, when I eat leafy green salads in restaurants, I have no adverse physical reaction. But a few times, I have eaten this type of salad in restaurants and it caused me severe diarrhea, which strikes within a half-hour after leaving the restaurant. I am usually homebound by this for the next 24 hours, feeling weak and lethargic. This does not happen when I eat other foods, or homemade green salad. Can you tell me what chemical the restaurant or food processing companies may be adding? And how can I protect myself from this happening again? -- H.K.

DEAR H.K.: In addition to the lousy way it makes us feel, it is always a disappointment when eating -- an activity meant to provide nourishment and satisfaction -- makes us ill. And it can be troublesome to attempt to figure out what might have been responsible. The list of possibilities might include a developing illness, a reaction to one or more medications, a food allergy or sensitivity, or an eating establishment’s sanitation issue.

Food poisoning is on the “suspect” list in the case you describe, especially given that you have not experienced this type of reaction when eating other foods or making salads at home. There is the possibility that something contaminated was included in the meal; this can include the food, salad dressing, condiments, beverage, dishes, silverware or any unclean item or surface you were exposed to while visiting the establishment. (I have assumed your hands were washed.)

It is difficult to identify the responsible element(s) until some theme emerges. Thoughts that added “chemicals” are responsible would not be at the top of my list, unless such events occur regularly. As for greens: Last year, there were several incidences of E. coli infections linked to romaine lettuce.

Is a particular restaurant more involved than others with these episodes? You may be able to get more information by speaking with friends who frequent that same establishment. Or, you could check social media to see if others have had similar experiences -- but I advise caution, as critical posts can be baseless comments made by competitors.

Bottom line: With the details provided, it is difficult to point your fork at the salad greens and say they made you sick. With no obvious answer at this time, a shift to “detective mode” will increase the odds for success. That said, I hope that this does not happen again! Write back if you learn more. For more on food safety, see b.link/food22.

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: During a recent online nutrition class, there was a discussion about whether fruits and berries have the most antioxidants, and other beneficial substances, when they are the sweetest. This was the position taken by the teacher and supported by some students, but I argued the opposite. Who is correct? -- P.E., Chicago

DEAR P.E.: You have my support. The “mission” in the plant world, if we can think of it like that, is to grow and reproduce to propagate the species. Unlike animals, plants can’t get up and run away from dangers. Successful plants have evolved to resist threats from limited resources, insects, microorganisms and animals, to name a few. The environment is also a player. A report in the February 2020 issue of the National Academy of Sciences’ journal reported that unchecked global warming might contribute to the extinction of up to one-third of all plant species by 2070.

Successful plants have evolved to create physical and chemical protections to facilitate their growth and the development of seeds needed for reproduction. Chemicals produced by plants (phytochemicals) represent an in-house tool kit for defense and repairs.

Where do antioxidants fit in the picture? From the moment its first shoot emerges, a plant relies on the sun for energy. Too much radiation from the sun, however, can result in oxidative damage to plant tissues. Fruits and vegetables make antioxidants as protection against destructive oxidation. These antioxidants are for the plant’s protection, not ours.

Another side of the story involves seed distribution. The wind can serve that purpose; in those instances, seeds are light in weight and designed for flight. Some seeds get distributed through barbs, which get them carried away on animal fur. Other seeds develop inside fleshy fruit that gets consumed by animals, passes through the digestive system and is then deposited in a new location.

Of relevance to your class discussion is that the protective phytochemicals are at their peak before the seed is ripe. The plant’s entire resource investment is near its conclusion. The last thing the plant needs is an animal feeding on the fruit before the seed is ready for the dance. Unripe fruits don’t taste great -- that’s the way it should be -- and antioxidants contribute via their bitter, astringent or acidic tastes.

Once the seed is ripe, however, the goal shifts to facilitating seed distribution. Sweetness develops when “unsweet” complex carbohydrates get broken into simple sugars -- usually fructose, which is about 1.4 times as sweet as sucrose. Along with that come changes in color and odor: all signals to animals that dinner is served.

You can see, and hopefully explain to the class, that a piece of fruit harvested before it reaches its peak ripeness can, of course, be less sweet. But less sweetness doesn’t necessarily mean smaller amounts of beneficial substances.

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.