DEAR DR. BLONZ: There have been periods in history, such as the Irish potato famine, when people had to survive with limited access to food. I follow a healthy, varied diet, with organically grown produce preferred when available. I avoid heavily processed foods. My question is: If humans can survive periods when they don't get all their requirements, are daily nutrient requirements necessary? -- T.S., Raleigh, North Carolina

DEAR T.S.: We can survive periods of inadequacy through the human organism's evolved ability to recycle nutrients when intake is deficient. This is not a 100% reliable process, as it depends on the nutrient involved and on potential complications, such as infection, illness or stress. This ability can be lifesaving in the short term, but that would be merely surviving, not thriving. For an informative article on human diet evolution, see b.link/fh5ukwc.

Essential nutrient levels are affected by the efficiency of absorption, the rate of excretion, and whether and how a particular nutrient gets stored, retrieved from storage and recycled if needed. These elements can adjust as short-term adaptations to a low intake, but prolonged deficiencies result in a drain on availability, with impacts on systems that rely on their presence. Quality of life is also affected by a limited nutrient reserve.

So, assuming there is air to breathe and water to drink, we can last without any food for a month or so, depending on our age, initial state of health, the amount of body fat (spare energy) present and the environment in which the deprivation takes place. (A "you call that living?" descriptive might be appropriate here.) Adding calories can help a bit, but it is limited without the needed raw materials and essential nutrients. The evidence supports the wisdom of daily nutrient intakes.

Nutrient requirements were first developed in the 1940s during World War II, when effective rations for soldiers had to be formulated. The first index was the minimum daily requirements (MDR). This was a measure of the minimum amounts of protein, vitamins and minerals to prevent a deficiency or other metabolic malfunction correctable by providing the deficient nutrient.

This was calculated by dividing the amount stored in the body by the number of days of zero intake it would take for the body to show signs of a deficiency. Consuming the MDR could effectively prevent such a deficiency. But this was measured in young individuals in excellent health, meaning they had no medical issues or medications. We have learned how various health conditions and medications affect nutrient requirements.

Since then, we have moved to recommended dietary allowances (RDAs) -- no longer using "daily" in the name. This is considered the average daily intake to satisfy the needs of up to 98% of healthy individuals. You don't need to meet every nutrient requirement every day, but as our health is involved, why mess?

You raised the topic of the Irish potato famine. This terrible event was made possible through that culture's primary subsistence on potatoes, with bits of dairy and fish. Their narrow focus exploded into tragedy following a blight that affected the potato crop, resulting in seven years of starvation, disease and emigration. Check b.link/2vphwvh for more on the Irish potato famine.

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’m on a medication (spironolactone) that is to be taken with food so as to not upset my stomach. I’m not an early-morning eater. Does a good-sized banana plus coffee satisfy that requirement? Thanks -- C.L., Richmond, California.

DEAR C.L.: The “with food” recommendation can be for various reasons, such as when a particular type of food facilitates absorption, or if food limits stomach irritation if the medication were to sit in direct contact with the stomach lining. It depends on the drug and the health situation involved. There should be information provided with the prescription, or you could ask the prescriber or your pharmacist what “with food” would mean for that particular medication. This allows you to speak with professionals who can consider any other medications or health conditions you are being treated for.

You provided the name of your medication (spironolactone); that is one that can irritate the stomach lining, so the presence of food would limit that unwanted effect. As to whether your banana and coffee would suffice, that really depends on how your body responds. Be aware that coffee on an empty stomach can be an irritant in its own right. A small amount of protein and fat may help here, but you and your health professional will be the final arbiters. For more on spironolactone, see b.link/mdii2b2e.

DEAR DR. BLONZ: I see recommendations to drink hot water first thing in the morning on an empty stomach for its “many metabolic benefits.” The list includes detoxification and digestion because hot water can stimulate blood circulation and the lymphatic system to flush toxins from the body. Sounded too good to be true, but the poster cites the Journal of Neurogastroenterology and Motility (2010) for support. This would be so easy to do if it worked. There is no money to be made from hot water, so why would one post such information if it were false? Is there anything to this? -- F.P., Oakland, California

DEAR F.P.: Those claimed benefits from drinking hot water first thing sound too good to be true? Precisely! Social media is set up to reward blatant nonsense, as wacko posts encourage people to engage and criticize, and the conversation begins. You may find defenders of the silly stuff and wonder what that’s all about. Those defenders can be secondary identities of the original poster, all designed to increase the number of posts. Viral conversations can result in financial rewards for the posters of falsity. Don’t get conned by the blatant run of health nonsense on social media.

Finally, I found the citation referenced in that hot-water post. It does not support the claims; rather, it concerns the use of hot water by people with a specific swallowing disorder. It is not uncommon for misinformation promoters to make things up and falsely cite research. Always check with evidence-based resources. Irrespective of whether this has anything to do with your interest in this topic, be aware that swallowing disorders are nothing to be trifled with. For more on this topic, see the article at b.link/n82uxzp.

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: Thank you for the column on muscles in the aging body. As a trainer who works with many as they age, I've found that most don't realize adults can lose about 5% of their muscle mass every year. The more muscles you have, the higher your metabolic rate. As highlighted in the attached article, adults can lose 3% to 5% of their muscles per decade, with this rate accelerating after 60. This is a natural process referred to as sarcopenia. The decline, as you mentioned, can be slowed and even reversed with regular resistance training. It is important to take the time to find a reliable trainer and lift weights. -- D.B., Del Mar, California

DEAR D.B.: I appreciate the comments and compliment your career focus on helping clients in this important area of life and health. Fitness and an active lifestyle remain one of life's best returns on investment. Keep it as a lifelong relationship rather than turning to it only after an illness, injury, surgery or when you realize you are no longer able to keep up with your peers.

Take it easy when you start, especially if there are problem areas or medical issues to consider. If you are a senior who has been inactive for a while, be sure to check in with your primary care physician before beginning any training program. Fitness is a worthy goal, but the last thing you want to do is rush things. To avoid overloads or other problems, seek the advice of a trainer who is experienced in working with seniors and who has successfully dealt with your issues.

Consider taking a complete set of body measurements and noting your clothing sizes before you start. Your clothes may begin to fit differently over time. Hunger may increase with your activity level, but seek to satisfy hunger with fruits and other low-calorie, whole foods, all eaten slowly with good hydration. Keep track of your weight weekly, but be less concerned with the number and more comforted by working toward the benefits of a more active lifestyle.

DEAR DR. BLONZ: I am looking to get certified in fitness and nutrition. If you know any home study courses, websites, or anyone I can call it would be very helpful. Thank you in advance for your help. -- A.C., Charlotte, North Carolina

DEAR A.C.: I see this a lot -- especially on social media -- and advise caution when dealing with certificate-granting organizations. Do some in-depth checking on any organization that grants fitness or nutrition certificates. Do scientists and academics in the field recognize such credentials as legitimate? Is the certificate-granting faculty trained with bona fide academic degrees -- not ones granted by a similar certificate-granting organization? Don't be overly swayed by the fact that an organization claims to be accredited. Outfits can form their own "independent" organizations and accredit themselves! Be wary, or you may end up with nothing more than a worthless piece of paper.

It is difficult to gain a real knowledge of nutrition via a certification/mail-order course. Nutrition is a science based on biochemistry and complex physiological concepts, and traditional colleges and universities require years to teach the basic tenets of these sciences. Consider taking community college or university extension courses in fitness/nutrition to learn more about the field you want to pursue.

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.