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.

DEAR DR. BLONZ: Is there still vitamin C left after a potato is baked or french-fried? According to a USDA database, one cup of baked potatoes contains about 10 milligrams of vitamin C. Authorities I checked with say that heat destroys vitamin C, and baking or frying exposes potatoes to significant amounts of heat. Are “heated” potatoes still a good source of vitamin C? -- F.D., Anderson, South Carolina

DEAR F.D.: Food preparation methods involving high heat can indeed destroy heat-sensitive (or “heat-labile”) nutrients, which include vitamin C and thiamin (vitamin B1). With normal cooking, this will be a reduction, not an elimination. That level in the USDA database does reflect an estimated 50% reduction of the amount of vitamin C found in a raw potato.

A food is considered to be a “good source” of a nutrient if one serving provides between 10 and 19% of the Daily Value. The adult Daily Value for vitamin C is 60 milligrams. Three-and-a-half ounces (100 grams) of baked potatoes does provide about 10 milligrams of vitamin C, which meets that requirement. There is less vitamin C in french fries, as that process involves higher temperatures (albeit for shorter periods). But even if french fries manage to clear the 10% bar for one or more of the potato’s nutrients, this would not qualify fries as a go-to food to meet your nutritional needs.

DEAR DR. BLONZ: A company that sells Tupelo honey is claiming that it is OK for diabetics because of the levulose content. I am not familiar with levulose. Are you aware of research to affirm that claim? -- G.G., San Jose, California

DEAR G.G.: Sugars can go by multiple names. Fructose, also known as “fruit sugar,” is also called levulose. Glucose can also be called dextrose, or “blood sugar.” Table sugar is made up of glucose bound to fructose, whereas honey also contains these two sugars, but not bound together.

Honey tends to have more fructose than glucose, and Tupelo honey usually has more fructose than other varieties. Does this make it safer for diabetics? Doubtful. There is no magic (or science) to support that claim.

Adjustments can be made to allow for a small amount of honey, when used as a minor ingredient. Still, simple sugars such as honey -- whether Tupelo or clover -- can impact a diabetic’s blood sugar level, so caution is advised. If you have specific questions about your particular situation, it would be beneficial to consult with a registered dietitian.

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: Dietary supplements to help with hair growth seem to focus on amino acids and protein. My concern is that I have also heard that they cause you to gain weight. I don’t need to gain weight, but would like the extra protein for my hair. -- M.T., Hayward, California

DEAR M.T.: While amino acids and protein have caloric value, they do not have any special abilities to cause weight gain. They contain approximately four calories per gram, which is similar to carbohydrates, but less than fat (nine calories per gram). The body uses amino acids as building blocks to make protein, but it can use them for energy when other sources are in short supply. If the body has all the amino acids it needs to make its protein, and there is also sufficient dietary energy, the body converts its excess amino acids into fat for storage. The same can be said for anything that contains calories.

Hair is made up of protein, and many hair products do contain protein; this includes products taken internally and those used externally. Nutrient deficiencies can affect bodily systems and the things they make, and this would include our hair. In that sense, it is accurate to say that amino acids and other nutrients are “good” for the hair -- at least, good to the point that requirements are met. But there is no evidence to believe that taking in extra amino acids, more than the body needs, can result in a healthier head of hair. Perhaps the most significant influences on your hair are the products and treatments used externally, but that is a discussion you might have with the individual you trust for your hair care.

DEAR DR. BLONZ: While not a nutrition question, this does deal with health, so I am hopeful you can respond. My question is about electronic ab exercisers. They claim to be able to give you six-pack abs with no calorie restrictions and no other exercise. I would like your opinion of these devices, and whether or not you think they work. -- T.F., Oklahoma City, Oklahoma

DEAR T.F.: In the words of the Federal Trade Commission, it is pure “pump fiction” to think that the electronic muscle stimulators sold to the public can deliver “rock-hard” or “six-pack” abs. These machines are considered to be medical devices, which means they require FDA approval to be legally marketed. But don’t assume that if you see something for sale, it has been approved.

The concept is that delivering electrical stimulation through the skin causes muscles to contract; I have no problem with that. But then the claims go further, saying that such contractions can resculpt the affected muscles into that chiseled, six-pack appearance, all without any need to adjust diet or exercise. There is some history here: Approved medical devices have been used to stimulate nerves to help prevent muscle wasting after surgery, or during periods of extreme inactivity. But this is not the same as building and sculpting new muscles. There is no evidence that these devices can do that, and no FDA approval to claim such an effect.

Read this (albeit dated) article at the Federal Trade Commission for more information: b.link/abexercisers. Hopefully, this will help you make a more informed decision.

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.