Dear Doctor: Just how much of a role do personality traits have in determining how long someone will live? Recent news reports have suggested that they're important, but the explanation didn't really make that much sense to me.

Dear Reader: The idea that the way we view or interact with the world around us can affect our health is an intriguing one, and several studies have taken on the topic over the years. Since we're not sure which of these you're referring to, we'll look at a couple of the most recent ones.

Researchers in Italy who studied a group of 29 elderly men and women aged between 90 and 101 said their findings suggest that mental outlook plays a significant role in well-being. This is a departure from other approaches to the topic of longevity, which have focused on genetics. Despite the typical health issues you would expect to see among individuals of this advanced age, the subjects of the study were found to have more self-confidence than their younger relatives, who were also included in the study.

Using questionnaires and interviews, the researchers concluded that the elderly group, who had more positive feelings about their lives than their younger relatives did, exerted greater control over their lives and surroundings. They achieved this by being stubborn and domineering, personality traits that the researchers tied to their longevity. They also had strong ties to family, to their homes and land, and to their spiritual practices.

Thanks to this blend of resilience and optimism, the group of elders appeared to have struck a balance that helped them weather the many challenges they faced over the decades. And while lifestyle factors like diet and exercise were not the focus of this particular study, the researchers agreed that they are also quite likely to play a role.

Another study, this one based in England, analyzed the health and lifestyle data of 500,000 individuals ranging in age from 37 to 73. The researchers wondered whether being neurotic would have an effect on the length of an individual's lifespan. When they looked at the broad category of neurosis, they found a "weak correlation" between being neurotic and a shorter lifespan.

However, when they separated the data into sub-categories, they got a surprise. It turned out that neurotic individuals who self-reported their health as either fair or poor actually had longer lifespans. Neurotic individuals who said they were in good or excellent health didn't get the same boost to longevity. In this study, the conclusion was not that the neuroses themselves extended an individual's life. Instead, the personality traits associated with being neurotic led people to be more aware of their aches and pains, and to be more aggressive in seeking medical care. With more frequent assessments and screenings, serious conditions such as cancer or cardiovascular disease would be caught earlier and would thus be more responsive to treatment.

For those of us who are neither neurotic nor 90-year-olds living in rural Italy, there are still useful takeaways from the studies: Have regular medical checkups, be vigilant about basic screenings, and strive for a positive outlook even in trying times.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

Hello, dear readers, and welcome to autumn! You've been keeping our mailboxes full, so let's dive right in.

Cannabidiol, or CBD, one of several hundred compounds found in cannabis, continues to generate interest. Research has shown CBD to have analgesic and anti-inflammatory properties, and the FDA recently approved the first CBD-based epilepsy drug. We heard from a reader in Pennsylvania who uses CBD for pain and inflammation. He asked us to make clear that one can buy CBD extracted from hemp. "I have 19 broken bones and three bulging discs, and I haven't felt this normal in 12 years," he wrote. "I am a believer in hemp CBD."

Hemp contains virtually no THC, which is the psychoactive compound in marijuana. However, it's a close cousin to marijuana and remains in a legal gray zone in several states. The good news for CBD users is that several senators are working on legislation to make hemp products legal throughout the United States.

After a recent column about sunscreen, a reader asked us to point out that babies need special sunscreens that are different from those used by adults.

Infant sunscreens consist of mineral blockers, like zinc oxide or titanium dioxide. Adult sunscreens contain chemical additives that are not suitable for babies' delicate and sensitive skin. It's generally agreed that sunscreen use should begin at about 6 months of age. Until then, protect your baby from the sun with physical barriers like blankets, hats and umbrellas.

A column that referred to the anti-inflammatory properties of fish oil supplements for individuals with rheumatoid arthritis led a reader in Ventura, California, to wonder whether flaxseed oil could deliver the same results. Of the three main types of omega-3 fatty acids derived from foods and used by the body, flaxseed oil contains one, which is alpha-linolenic acid, or ALA. Although our bodies can convert ALA to the other two types of long-chain fatty acids (EPA and DHA) that render benefits, the degree of success relies on the presence of specific vitamins and minerals, as well as a genetically controlled enzyme process.

Bottom line: Yes, flaxseed oil will provide all the ALA you need. But due to the conversion factor of the remaining two omega-3's, it's not considered to be an even exchange for fish-based oils.

A reader from Louisiana who experiences "hanger," the irritability that can accompany a drop in blood glucose, thinks our column fell short of the mark. "Perhaps the answer could have included suggestions about what snacks would be helpful to the daughter in maintaining an appropriate sugar balance," she wrote. "The only level of control I have found that works is being able to eat the right foods on a more frequent basis than the average person."

Point well taken. If hanger is a part of your or a loved one's life, plan ahead with protein-based snacks like nuts or nut butters, cheeses or a protein bar. Do include complex carbs like fruit, veggies, legumes and whole grains. Don't reach for candy or other simple carbs, as they'll send the blood glucose roller coaster into overdrive.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: I'm 67 years old and because I was told that it's harder for folks my age to get enough vitamin B12, I started taking a B complex supplement. My husband, who is 72, did, too. But now it turns out that these are linked to lung cancer? What should we do?

Dear Reader: Over the years there have been occasional findings in a range of studies that certain B vitamins were associated with an increase in lung cancer risk. Known as one-carbon metabolism-related B vitamins for the way they behave in the body at a molecular level, they include B6 and B12, which are commonly found in B vitamin supplements. Because the data into the link between these particular B vitamins and lung cancer risk were inconsistent, and because the use of vitamin supplements is hitting an all-time high, researchers homed in on the topic. Their findings were published last year in the Journal of Clinical Oncology.

The scientists analyzed data collected from approximately 77,000 women and men who are taking part in a long-term study conducted by a cancer research center at the University of Washington. Known as the VITamins and Lifestyle (VITAL) Study, participants self-report health data through the use of questionnaires. DNA for analysis has been collected from about 70 percent of the study's participants. They range in age from 50 to 76 and live in a 13-county area of western Washington State. The authors of the B vitamin study were primarily interested in those who had been taking B vitamin supplements for at least a decade.

According to the findings of the B vitamin study, male smokers who took B6 or B12 supplements at very high dosages had three to four times the risk of developing lung cancer than men who smoked but did not take the supplements. Non-smoking men who took the supplements doubled their lung cancer risk.

Surprisingly, these findings did not extend to the women in the study. The B vitamins that the study participants were taking came from individual supplement sources. They did not come from multivitamins. This is an important distinction because the link to cancer occurred in study participants who were taking B vitamins at high dosages. The supplements delivered more than 11 times the recommended daily amount of B6, and a whopping 23 times the RDA of B12. As the author of the study has pointed out and as you have probably noticed yourself, B vitamins are now in vogue. They're so popular that, in addition to the scores of oral supplements, you see B12 shots regularly offered on demand in health food stores and some pharmacies.

B vitamins are vital to our well-being. However, the best way to get them is through a well-balanced and healthy diet. Eggs, dairy, fish and meat are good sources of B12. Many products, like breakfast cereals and soy or rice milk, are fortified with the vitamin. If you do need a supplement, read the label carefully and choose a product that doesn't provide more than the recommended daily allowance.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)