DEAR DR. BLONZ: I am interested in nutrition and have heard about the benefits of folates, and how we need methylfolate, not other forms. Is folate the same as folic acid or methylfolate? Thanks! -- P.D.

DEAR P.D.: Nutrition is a branch of science focused on the intake of foods and their conversion to nutrients and energy in the human body. It's important to note that dietary supplements are a consumer product, so expect companies to argue the superiority of their product over their competitors'. Always consider the source, and seek evidence-based information rather than relying claims made by these businesses, whose main focus is making the sale.

Folate is a generic term referring to a family of related compounds. Throughout its history, this essential nutrient has been known by many different names, including Wills factor, vitamin M, vitamin Bc, vitamin B9, vitamin B10 and vitamin B11. Folic acid is a synthetic form not found in nature; it is used in supplements and to fortify foods. (More about this essential nutrient can be found at at b.link/d6arknb.)

In nature, folate's essential core can be found along with a side chain that reflects what it does in that particular plant or animal tissue. When consumed, our digestive system pares off extra folate to get it ready to pass through its absorptive portal in the upper part of the small intestine. Once through the intestinal wall, folate travels to our liver, where it is activated for use.

One can get the folate they need from a healthful diet. Good sources of folate include green leafy vegetables, organ meats, legumes, orange juice, beets, avocado and broccoli. Taking folate, folic acid or methylfolate supplements at their recommended levels is fine for most people.

One exception to consider is those with a genetic issue called methylenetetrahydrofolate reductase (MTHFR), which makes the body less effective at folate activation. For those affected, an adequate dietary intake is especially key. If their folate intake is marginal, they could benefit from methylfolate, the more active form. Ask your physician, as there are tests that can indicate whether your body needs special considerations regarding folate. (Read more about this gene variant and folic acid at b.link/mesk4bz.)

DEAR DR. BLONZ: You always recommend whole foods so that one gets nutrients where they naturally occur. But does that mean it's best to take vitamin C with foods that naturally include vitamin C, or is it just as effective to take it alone with water? What's the best time of day to take vitamins? -- C.F., Scottsdale, Arizona

DEAR C.F.: Vitamin C can be taken with or without C-containing foods. Generally, it is preferable to take supplementary vitamins and minerals at mealtime: When food is present, the body is more attentive to the digestive system and the blood supply can pick up the incoming nutrients. The main takeaway: It is more important that you get your nutrients than to be overly concerned about what time of day you get them. The foods you eat should always be center stage. Supplements are just that: supplements.

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 5 feet 4 inches tall and weigh 110 pounds on a good day. My concern is that I have found that 1,000 calories is the most I can consume each day without becoming obese. This seems a bit under what I should be able to eat, but the scale has its persuasions, and I dislike letting myself go. I wonder how to determine an ideal body weight and daily calorie count. -- F.S., Scottsdale, Arizona

DEAR F.S.: The "ideal body weight" (IBW) was developed to help estimate how long it takes for drugs to be metabolized, which helps to determine appropriate doses of medications.

According to reference tables, an IBW for an adult of your height is between 97 and 127 pounds for females, and 114 and 143 pounds for males. Overweight is considered to start at 10% above a person's IBW, and obesity begins at least 20% above. At present, you show little risk of being overweight or obese. (For more information on ideal body weight in relation to height and age, see b.link/m6jdjc8.)

The 1,000-calorie daily limit you mention is on the low side for your height and weight. Consider discussing this concern with your health professional to rule out any metabolic issues, medications or other factors that may be at play.

What is a reasonable number of calories to consume every day? Estimates for an inactive adult are 10 calories per pound of body weight. A sedentary adult who is minimally active most of the day would need 13 to 14 calories per pound. An adult with a moderate activity level would need about 15 calories per pound of body weight, and very active adults need about 18 calories per pound.

These numbers are averages. The greater one's muscle mass, the more energy one needs -- even when just sitting around.

DEAR DR. BLONZ: I get nutrients, including protein and dietary fiber, from my daily use of 100% whole wheat bread. I like my bread toasted for breakfast and for sandwiches, and I wonder if there is a loss of nutrients when toasting bread. -- N.C., Raleigh, North Carolina

DEAR N.C.: The heat-sensitive vitamins include vitamins B1 (thiamine), B5 (pantothenic acid), B6 (pyridoxine), B9 (folic acid) and C (ascorbic acid), as well as some amino acids, which are the building blocks of protein. (Minerals are not affected by heat.) Lysine, an essential amino acid in grains, is an example of a nutrient that would be affected by toasting. Heat-sensitive nutrients are in grains but are more abundant in other foods. You might benefit from avoiding the toaster if toasted bread were your primary food, which it shouldn't be. There are plenty of other healthful foods to enjoy.

Take the amino acid lysine, for example, which comes mostly from animal proteins, soy and legumes. Heat has an impact, but the slight decrease of lysine in toasted bread is considered negligible. (For more on vitamins and their primary food sources, see b.link/pbq4rwb. For an explanation of the amino acids and their food sources, see b.link/9tc63kb.)

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 have shifted from animal sources to tofu as my primary source of protein. I am about 5 feet tall and I weigh 104 pounds. Is there anything about how tofu is made that I need to consider, and how much tofu should I have daily to satisfy my protein needs? I use tofu in a shake in the morning and add it to soups and salads. I scramble it, and I'm familiar with many other ways to prepare it. -- S.T., Tulsa, Oklahoma

DEAR S.T.: One serving of meat, poultry or fish is approximately 3 ounces, equivalent in size to a deck of playing cards. When trimmed of all visible fat, one serving would contain approximately 25 grams of protein. A cup of extra-firm tofu contains an equivalent amount of protein.

One way to estimate your recommended daily protein intake in grams per day is to multiply your weight in pounds by 0.36. A 104-pound body weight would require 37 grams of protein per day. (For more on protein recommendations, see b.link/hva5ju7.)

You indicate that tofu is your main protein source. Enjoying tofu is fine, but a single food should not serve as your dietary focus. Be sure to include other sources of protein. For vegetarians, these other sources might include nuts and seeds or a well-balanced diet containing grains and legumes, as these provide all the essential amino acids the body needs to make protein. For others, protein can come from fish, poultry and dairy, and red meat on occasion. The issue is not so much the source of the protein as the complement of other foods in the diet.

Tofu is made from soybeans that have been soaked, crushed, cooked and filtered. (For more on soybeans, see b.link/7y7jtya.) Calcium sulfate is then added, which causes the soy pulp to form a gel. The water is then removed as the soy is pressed into cakes. Tofu has a relatively high level of polyunsaturated fats, which can turn rancid when exposed to air -- especially warm air.

Fresh tofu must be packed in water and kept refrigerated. When purchasing fresh tofu, make sure it has been properly packaged and stored, and you should take it home in a well-sealed plastic bag that contains water. There are other options, one of which is to buy cakes of tofu in refrigerated, commercially sealed, water-filled packages; another is to buy tofu that is vacuum sealed in an aseptic package.

Discard tofu if the storage water becomes cloudy, if a slippery film develops on the surface, if you notice any unusual smells or if it takes on a pinkish tinge -- usually the effect of exposure to air. If the storage water is changed every day, fresh tofu can last up to two weeks in the refrigerator.

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.