DEAR READERS: You may have noted an increased number of self-proclaimed "experts" making dubious diet and health claims lately. These tend to come from those who eschew any obligation to be evidence-based, and their pronouncements often spread like weeds on social media. This is not what you want when looking for objective, reliable explanations for serious health issues; it is particularly dangerous during a pandemic's added stresses and complexities.

It helps to understand that scientific research is a complex cuisine, with the principal investigator serving as the equivalent of an executive chef. Unlike preparing an evening meal, research is a process that takes years to plan, conduct and analyze before any results are ready for consumption. Funding is pivotal; it governs what gets done, who will be available to do the work and, in the end, how the "serving" of science gets digested by the public.

Scientists at research institutions rely on grants from federal and private sources to keep their laboratories in operation. Competition for limited funds continues to increase, and the situation shows no improvement. Grant applications are reviewed by scientists selected for this purpose; the agencies distribute their funds according to priority scores assigned during evaluation. Many turn to industries and grant-giving foundations for their funding. This can mean looking at an issue from a different perspective: usually, one of interest to the organization writing the check. For many scientists, grant-writing takes up a big chunk of time. Some take courses on how to write better grants. Others form collaborations with scientists who have a better funding track record.

This reality behind scientific research is rarely understood or appreciated, and it helps explain what might come across as the conservative nature of mainstream science. How can one justify pursuing ideas on the fringes of science when such pursuits have a lower likelihood of funding? Consider, also, that challenges to mainstream thinking may place an individual at odds with the senior faculty members who will preside over their academic tenure (aka secure employment) decisions.

Even if initial research dollars are received, tackling new concepts can yield unclear results in the opening experiments. This can limit publishable results and affect the chances of a grant renewal. Scientists often opt to conduct smaller pilot experiments to help them design a better study; these can produce results more rapidly, while letting them know whether their theories make sense. Positive pilot study results can affirm theories, help with experimental design and increase the odds of future funding.

The message here: Don't assume that any questionable theories you hear have been put through the controls and constraints of the scientific process. To be our own best advocates, we each must ensure that the people providing advice are the real deal. If they're passing themselves off as experts, look into their training and education; find their peer-reviewed publication record; research who they work for. What are their accomplishments, outside of promoting a particular take for an organization or selling products claiming to provide a needed fix?

Stay away from those without appropriate academic and clinical training in the sciences. Simply because an individual claims mastery over their own experience with a health issue does not make them an expert for others facing the same challenge. If they present new concepts, be sure they provide support from objective, independent, science-reliable (preferably academic) sources.

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 am seeking advice about eating various types of foods together, given that many are digested and absorbed differently. Proteins must be taken apart by stomach acids, for example, but carbohydrates and fats do not require this at all. When eating different foods at the same time, I am concerned that this is putting unnecessary stress on my body.

I have periodic digestive problems, and I was wondering if this might be involved. -- S.F., Phoenix

DEAR S.F.: Theories about "food combining" emerge every now and then: twists on the idea that the way foods are combined, or not, is the key to digestive health. Easy-to-digest foods such as fruit should not, the theory goes, be eaten with proteins or fats, which take longer to digest. The assumption is that having them simultaneously delays the fruit's digestion and causes its sugars to ferment and putrefy, which contributes to digestive problems. (This is a bit bogus, if only on the basis that stomach acids do not create a fermentation-friendly environment.) Other "forbidden" combinations include starchy foods, such as bread or potatoes, eaten with proteins, such as meat or fish.

There's no reason to believe this theory. The beauty of our digestive system is that it's designed -- from the mouth to the other end -- for a mixed diet. Different types of foods are handled in designated parts of the digestive system, which evolved to create an effective "disassembly line."

While it's likely that some people have found that certain food combinations don't work for them, this is more an indication of personal habit and preference than a defect of the human digestive system. There appears to be no physical reason not to include various foods at every meal. (Note: This is different from eating too fast, which can cause problems with even the most healthful diet. Read more on this at b.link/qupvvk.)

Eating can be one of life's great pleasures, so I encourage you to seek medical advice, or guidance from a registered dietitian, to discover what might be behind any recurring digestive problems.

DEAR DR. BLONZ: What is the difference between pasteurized and ultra-pasteurized dairy products? -- M.L., via email

DEAR M.L.: Pasteurization and ultra-pasteurization are heat treatments designed to reduce potentially harmful microorganisms. The two differ in the amount and duration of heat used.

Pasteurization heats a dairy product to 160 degrees F for 15 seconds, while ultra-pasteurization heats the product to 280 degrees F for up to 3 seconds. The higher heat used in ultra-pasteurization eliminates more bacteria and results in a shelf-stable product, but it can affect flavor.

Ultra-pasteurization is usually done on products such as half-and-half or whipping cream. But ultra-pasteurized milk can be found in stores in remote areas that don't sell a high volume of perishable products.

Once opened, both pasteurized and ultra-pasteurized dairy items require refrigeration.

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 found an unopened pint of ice cream in my freezer that had been buried for about a year. I was disappointed to see that it had ice crystals, just like another container I had opened and resealed a number of times. What causes this, can it be stopped, and is there any danger from eating older ice cream in which this happens? -- S.Q., Chicago

DEAR S.Q.: Harmless water crystals can form on the surface of frozen foods during storage as the product's temperature fluctuates above and below freezing. Water typically freezes into large ice crystals, but such crystals in a frozen desert would lend an undesirably coarse texture.

There are methods to keep crystals tiny in ice cream and other frozen desserts; one involves constant stirring while the product is gradually chilled to the final storage temperature. When done correctly, it only allows mini crystals to form, and the dessert retains its smooth texture. Modern techniques chill frozen desserts using liquid nitrogen (-320 degrees F); with this method, the food chills faster than ice crystals can form.

Also important is temperature stability from the time the dessert is made until it is served. We all likely have experience with products whose temperature handling broke down along the way. (If this happens repeatedly, keep track of the particular products you purchased or the stores where you did so. Also investigate whether your freezer may be at fault.)

Ice cream in a carton can have a bit of "dead space" above the product. It is this, and any additional space once the dessert begins getting dished out, where the water in the ice cream can evaporate and refreeze during normal temperature fluctuations. The idea that water can vaporize at freezer temperatures may seem strange, but it can and does, given that the dry air in the freezer can pull the moisture out of the dessert. This rule of physics also helps explain the science behind freeze-drying and why some freezers had to be defrosted periodically (before the widespread use of mechanisms that do it automatically).

The longer it takes to use up a carton of ice cream, the greater the risk of crystal formation; keeping it out at room temperature for any length of time adds to the problem. However, crystal formation can be prevented by putting wax paper or some other moisture barrier on top of the dessert before returning it to the freezer. You may find that lower-fat frozen desserts have a greater tendency to form crystals, as these tend to have more water per unit weight.

DEAR DR. BLONZ: I am not allergic to milk, but I am definitely lactose intolerant. Where can I find a bread spread that contains no milk solids? -- J.B., San Diego

DEAR J.B.: The solids in milk will have proteins that anyone with a milk allergy must avoid. But your concern is lactose, and there is hardly any lactose in spreadable fats. With few exceptions, spreadable fats, including margarine and butter, get 100% of their calories from fat. This means there is no carbohydrate, and therefore no lactose, in these products. A cup of butter, for example, will have only about one-tenth of a gram of lactose.

Check the breakdown of your product on its Nutrition Facts panel to verify the absence of that carbohydrate. Even if there were a couple of grams per serving, it's doubtful that would be enough to cause a reaction in people susceptible to lactose intolerance. You might also consider adopting the European practice of using olive oil as a spread, with added herbs for flavor.

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.