DEAR DR. BLONZ: Are there significant differences in health effects between roasted and raw nuts? A raw-foods proponent at a local natural food store said that a half-cup of raw peanuts has 430 calories, but when roasted and processed into peanut butter, a half-cup will contain 780 calories. I expressed my skepticism, but wanted your take. -- J.S., Walnut Creek, California
DEAR J.S.: When roasting nuts, or any food, a series of chemical reactions takes place that can enhance the flavor and odor. With nuts, this can be accomplished with or without oil. Dry-roasting (without added oil) is done in specially designed ovens and utilizes hot air. Salt, paprika or other flavorings can be added as desired.
Because over half the weight of a nut, and over 70 percent of its calories, come from its fat content, dry-roasting results in only a nominal decrease in overall fat content. A flavored roasted nut can contain less fat per serving than a raw one because some of the weight is taken up by the added flavors and coating. Regarding nutritional value, any high-heat process will destroy some of the folate and thiamin (vitamin B1), but the other nutrients remain.
Raw peanuts have similar tastes with slightly different texture and flavors, but there will be comparable fat content to roasted nuts. With raw nuts, there is a slightly higher risk of microbiological contamination, so they are not recommended for immune-compromised individuals. Any raw peanuts should be stored in the refrigerator in a well-sealed container. Purchase from sources that use bulk containers where the newest nuts are added on top, with the nuts being purchased exiting at the bottom.
Finally, that comment about the caloric content of raw peanuts versus peanut butter is misleading. There will always be air in a cup of peanuts that is not found in a similar volume of peanut butter. If, however, you were to compare similar weights of these two foods, the caloric content would be comparable.
DEAR DR. BLONZ: Can you explain why vitamins and minerals expire? -- S.H., Arlington Heights, Illinois
DEAR S.H.: Vitamins are reactive compounds that play an integral role in the wide array of chemical reactions that comprise our metabolism. While mineral supplements tend to be quite stable, vitamins can slowly lose their potency over time. The factors that encourage breakdown are humidity, temperature, and light. Formulas that contain fat-soluble nutrients tend to break down the fastest.
The best way to store products is in a tightly sealed container in a cool, dark place. Many supplements include moisture-absorbing capsules or packets to help maintain product quality. Product expiration dates indicate when the vitamins can be assured of full potency, assuming, of course, that the product has been appropriately stored.
Send questions to: “On Nutrition,” Ed Blonz, c/o Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to email@example.com. Due to the volume of mail, personal replies cannot be provided.