DEAR DR. BLONZ: How do the nutritional needs of an older athletic individual -- that's me -- differ from one who has chosen a sedentary lifestyle? My lifelong friend, who happens to be the same approximate height and weight, doesn't do much exercise, and I keep trying to encourage him to get with the program, but he doesn't see the upside. -- F.L., Walnut Creek, California

DEAR F.L.: There is a big difference in how contrasting lifestyles impact the body, so don't think that the fact that you and your friend might wear the same size clothes be viewed as a pass for his non-active lifestyle. As for nutritional requirements, those for the average older athlete will be similar to those of an individual who is sedentary, with two exceptions: water and calories. Both require a varied diet that focuses on nutrient-dense fruits, vegetables, grains, nuts, seeds and dairy products, with a modicum of high-protein foods such as fish, poultry and meat.

The body's metabolism goes through radical changes as we progress through mid-life into our senior years. The need for dietary calories decreases because of the continually decreasing calorie-burning capacity of our cells. In addition, the digestive system, through which nutrients are digested and absorbed, gradually becomes less efficient. The ability to feel thirst also tends to diminish, resulting in an inadequate water intake.

The body's skeleton shifts into "negative balance." This is where the removal of minerals, such as calcium from the bones, proceeds more rapidly than they can be replaced. The net result is a gradually weakening bone structure and an increased risk of osteoporosis. A sedentary lifestyle allows all these changes to proceed unabated. When you're active, though, the body behaves differently.

Because muscle movement is required during exercise, the calorie-burning capacity of our cells does not decrease as rapidly. The bones need to retain more strength so less of their precious minerals will be lost. The joints will tend to retain more flexibility to help support the physical activity. Circulation, needed to provide fuel to the working muscles, improves, and the heart muscle tends to remain stronger. In essence, activity, even if it's only regular daily walks, will help to keep you younger, longer.

Water is especially essential before, during and after exercise because it helps to keep the body cool via perspiration. In addition, water helps to shuttle waste products from energy production out of the body through the urine. Dehydration, even when mild, impairs performance and can cause the body to overheat and malfunction. This can be especially dangerous in the older athlete because the kidneys do not operate as efficiently. Because one's awareness of thirst can be lost during exercise, it's best to make drinking water a part of any exercise routine.

I am hopeful that your friend will be able to grasp the big picture that activity should be considered an investment that is especially important for seniors. It not only affects the quality of our day-to-day lives and capabilities, but it bolsters the resilience with which we are able to handle the inevitable curveballs that life throws our way.

Send questions to: "On Nutrition," Ed Blonz, c/o Universal Uclick, 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 have an interest in "real food" supplements, specifically soy supplements, and would appreciate your opinion. You recently wrote about soy and thyroid hormones, but I am interested in soy isoflavones to help with the symptoms of menopause. I don't have much soy in my diet, and wanted to know if taking a supplement would be a good strategy. -- P.L., Chicago

DEAR P.L.: The idea of a "real food" supplement is a bit of a contradiction in terms: Nothing compares with real food. Science has only begun to identify the healthful elements in the foods we eat. Each new study can provide greater awareness about a specific component, and if the research sounds promising, it can breed interest in spinoff products in pill form.

But all this misses the "whole food" point. It is unlikely that a single element holds the key. The smart money rests with the concept that all of a food's elements working together -- that is, the whole food itself -- provides the magic. This makes perfect sense, as whole foods represent an interactive, nature-evolved system designed to survive. What's more, these systems have passed the test of time -- a critical asset when considering GMO crops, as they sidestep this process.

Now, on to the specifics of the soy isoflavones. The isoflavones are phytochemicals (phyto = plant) unique to soybeans. They have a number of abilities and are antioxidants, which may have a direct role in soy's beneficial effects.

Isoflavones have structural similarities to estrogen, but eating soy isn't like taking estrogen. The isoflavones don't function as estrogen in the human body. They only have a "weak estrogenic effect" -- only one-hundred-thousandth (1:100,000) as potent as estrogen. The build of the isoflavone is believed to play a role in some of soy's observed beneficial effects, as it may bind with the body's natural estrogen receptors in a way that lessens estrogen's negative effects. Higher levels of (human) estrogen, for example, are connected with an increased risk of certain hormone-related cancers, such as breast cancer. Studies have shown how populations eating soy-based diets have a lower incidence of breast cancer. Diets containing soy may also protect against colorectal cancer in women: A study in the February 2009 issue of the American Journal of Clinical Nutrition reported that for every 5 grams per day of soy food eaten, the risk decreased by 8 percent.

This is one reason health professionals have encouraged people to have more soy in their diets. For someone who wants soy's benefits, but is not able to have soy in her daily diet, your soy extract capsule may actually seem like a good alternative. I would tend to agree -- but with reservations.

First is the fact that soy foods offer much more than isoflavones. Soybeans contain protein, vitamins, minerals, fiber and essential fatty acids, in addition to other valuable phytochemicals. (Check the information sheet from University of California at Davis at goo.gl/0YcpKv.) If you only take the isoflavones, you miss out on other components that are likely to play a role in soy's whole-food beneficial effects.

Send questions to: "On Nutrition," Ed Blonz, c/o Universal Uclick, 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: What are your thoughts about using pork fat (like uncured bacon or pork belly) to prepare foods? I find the taste infinitely superior to butter for most cooking needs, and there is no evidence that it is harming my cholesterol levels. I normally store the stuff at room temperature, on the theory that that's how my grandma did it (just put it in a can and scoop it out as needed). How long is it safe to leave out? Is it likely to become carcinogenic at some point, or does it just get rancid if it's too old? -- E.D., Sacramento, California

DEAR E.D.: I would not classify lard as a "go to" cooking fat, but if you have an otherwise healthful diet and are in good health, the occasional use of lard should not pose a problem.

As to some of your specifics, it's unlikely that your lard will become carcinogenic per se, but some of the lipids may oxidize if it is kept at room temperature. Mono- and poly-unsaturated fats, and especially cholesterol, are susceptible to oxidation, and the consumption of oxidized cholesterol and oxidized fats can contribute to health problems.

Many people don't realize that lard is approximately 47 percent monounsaturated and about 12 percent polyunsaturated fat. About 41 percent of lard is saturated fat, and much of that is stearic acid: a saturated fat that has been found to have a neutral effect on blood lipid levels. Finally, there are about 12 milligrams of cholesterol per tablespoon of lard.

If you are intent on using pork fat, I would recommend keeping it refrigerated in a sealed container with a minimum of airspace. Lard manufacturers often use synthetic antioxidants such as BHA, BHT or propyl gallate to help preserve fats.

DEAR DR. BLONZ: You have mentioned that weight-bearing exercise is beneficial for the bones. My mom has recovered from a stroke and is not yet able to walk; it is unclear whether she will ever be up and about as she once was. She does exercises daily, but not of the aerobic variety -- more the "sitting and doing arm or leg exercises" variety. She sometimes has light weights strapped to her ankles or wrists while exercising. Would this be considered "weight-bearing" exercise? -- S.T., Phoenix

DEAR S.T.: Strength training that involves the use of weights, even light ones, is indeed considered a weight-bearing exercise. Given your mom's condition, it may be her best option for now. Most of the other weight-bearing exercises involve movements such as walking or jogging, where the weight of the body is alternately applied and removed from the long bones of the legs. Swimming, which is also an excellent exercise, is not weight-bearing, because it lacks this element.

Have her use caution so as not to overdo it, and, of course, make sure you apprise your mother's health professional of the details of her exercise regimen. Consider consulting with a physical therapist, a service covered by many health insurance plans, as this would provide a program tailored to your mother's specific needs.

Send questions to: "On Nutrition," Ed Blonz, c/o Universal Uclick, 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.