DEAR READERS: Often, the letters I receive reflect the rise in diet and health advice found online and through social media. While I welcome the increase in helpful, evidence-based information, it has, unfortunately, been rivaled by skillfully marketed stuff best described as "wacky."

Reasonable consumers must therefore take on the chore of sorting the science-based information from the worthless -- and sometimes dangerous -- cyber junk. Here are some of my "rules of the road" when looking for answers online.

-- Seek objective, evidence-based confirmation for the safety and efficacy of any health-related product, treatment or dietary supplement. The accepted standard: competent, reliable scientific evidence published in a reputable, peer-review journal. Websites that end in ".edu" (educational institutions) and ".gov" (government resources) are reasonable places to start.

-- To support a concept, there should be at least two clinical studies (that is, studies using people) done by independent teams, ideally teams that have no association with the product being tested. It is entirely reasonable that a company with a financial interest in a product would fund research about it, but exercise caution if that company's research is the only support out there.

-- Clinical research using subjects with various states of disease can offer insight into mechanisms relating to that condition. Still, it cannot be assumed that the same effects will occur in otherwise healthy, well-nourished individuals (unless that study has also been done). For example, an individual can feel sluggish if they have iron-deficiency anemia, and replenishing their required iron will increase their energy. From this finding, however, you cannot claim that an individual who is not iron-deficient to begin with will experience similarly increased energy if taking the same supplement.

-- Studies should undergo peer review before publication. This is a process where experts in the field, selected by the journal, examine the details of the work. The journal editor has the last word on whether the study is accepted as-is, accepted after making specific revisions, or rejected. Reputable journals should also reveal any conflicts of interest relevant to the studies they publish -- for instance, whether the authors have any financial interest in the success of the product or technique.

-- It is also essential to check whether the study used the precise substance and dose as that found in the product.

-- Many products use customer testimonials; these are designed to be seductive and to sound convincing, as are social medial videos! Testimonials should not be the sole reason you decide to buy a product. Don't be persuaded when the only available "positive" information comes from entities vested in the product's sale.

-- The concept of "They couldn't say that if it wasn't true" is misleading. There are a variety of ways by which health products get promoted; regulatory agencies cannot be expected to keep up with the ever-changing frontier of false, illegal and questionable claims.

-- Finally, be aware that the ingredients in health products and supplements can interact with each other and with prescription medications. Be upfront about what you take with any health professional entrusted with your care.

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: My partner and I are planning to start having children. My diet is fairly healthy, but far from ideal. I don't always eat all the fruits and vegetables I am supposed to every day, and I'll admit to occasional cravings for sweets and fast foods. (I am not yet pregnant, so I can't blame my cravings on that.) Which vitamins, minerals and nutrients play the most important roles during pregnancy? -- A.P., El Cerrito, California

DEAR A.P.: The simple answer is "all of them." The developing fetus depends upon mom to have all the essential nutrients in her body so they can be appropriately used as needed during gestation. That means your intake must be sufficient for you and your future bundle.

That said, there are a few standout nutrients.

One of the first parts of the body to develop is the nervous system, and folate -- also called vitamin B9 or folic acid -- plays a key role. The catch is that this nutrient must be present during the first few weeks after conception -- a time when most women are unaware they're even pregnant. Lack of folate during this time can lead to spina bifida, a birth defect in which one or more of the spinal column vertebrae fail to develop properly. As many as 75% of all cases of spina bifida are attributable to a folate deficiency during those first few weeks of pregnancy. That explains why the U.S. Public Health Service recommends that all women of childbearing age who are capable of becoming pregnant should consume at least 400 micrograms of folate per day.

There is also a particular need for iron, since the mother needs to expand her blood supply and the fetus needs to make its own. There also must be sufficient iron stores for the first months of a baby's life, during which the main food source could be iron-poor breast milk. This helps to explain why the RDA rises from 18 to 27 milligrams per day during pregnancy. (Most prenatal vitamins have an increased amount of iron.)

Calcium and vitamin D also stand out, as they are needed for bone development. Calcium absorption doubles during pregnancy, and vitamin D is needed for calcium absorption and utilization.

A final key: water, and fluids from any healthful source. Throughout pregnancy, a woman's blood volume increases by 50%, with the extra water helping to transport nutrients and oxygen to the developing child and carry waste materials away from the amazing construction project.

There are many informational resources on this topic available from health professionals, but also a mix of voices in social media. Avoid "unusual" takes on this most natural of processes, sticking instead with sources from academically trained experts. Check the information pages from the Office of Disease Prevention and Health Promotion (b.link/ess7e9) and from the American College of Obstetricians and Gynecologists (b.link/pnbr8y).

All the best to you both as you move forward during this beautiful time.

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: Please address the variety of weight-loss programs out there: They all seem to rely on very different approaches, but all claim success and have celebrities pushing them. Questioning someone from one program about a competitor's approach earned me an earful of criticism.

I was in great shape in high school and college, being active in sports, but now carry some extra pounds. I am working on this with exercise and diet. I started two weeks ago and have dropped five pounds so far. There is nothing easy about it. Whether or not I join a program, how can I tell which approach is best? -- F.S., Tulsa, Oklahoma

DEAR F.S.: There may be different twists on the weight-loss theme, but each profit-driven program will have its pitch and its press agents -- plus star pupils to swear by their approach, while swearing at others. Impartial published studies have made comparisons of various programs, and there are not many clinically significant differences between them. The best plan is simply the one you're motivated to stick with.

To achieve, and more importantly, maintain, weight loss is far from simple, and there are realistic limits to what can be achieved. The essential element is to focus on health promotion and a lifestyle and diet that make sense for your life.

Former athletes are often at the receiving end of weight gain as time marches on. There can also be complications when midlife health problems, including structural issues, create roadblocks that keep them from maintaining their activity level. Problems develop if they fail to taper what they're eating during the activity slowdown. If you have attended high school reunions over the years, you've no doubt observed these changes in certain individuals.

It takes personal character to recognize the issue and return to a healthful diet and lifestyle, making that your new norm. The bonus will be better health, irrespective of the final numbers on the scale.

DEAR DR. BLONZ: I have benefited from reading your articles for many years, but your recent column on fructose needs clarification. Kindly explain what you mean by "excess" fructose.

I am 92 years old, with controlled Type 2 diabetes. I have cut down on red meat and increased my intake of fruits, nuts and vegetables. However, I am worried about too much fructose. -- A.A., Walnut Creek, California

DEAR A.A.: Thanks for your comments, as well as your question. The adjustments you have already made are in line with commonsense, evidence-based recommendations. Any concerns about fructose should relate to that which is purposefully added to foods, especially processed foods, and not that which is naturally present in whole fruits and vegetables. Those whole foods should remain part of your balanced diet.

It is not until you get over 50 grams a day of fructose -- which would be over 10% of the energy in a 2,000-calorie diet -- that you slip into the treacherous land of fructose excess.

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.