1. An apoptosis inducing product obtained by heating at a temperature from room to 350 degree C for several seconds to several days under acidic to neutral conditions at least one substance selected from the following (a), (b) and (c): (a) uronic acid or uronic acid derivative; (b) a saccharide compound containing uronic acid or a saccharide compound containing uronic acid derivative; and (c) a substance containing a saccharide compound containing uronic acid or a substance containing a saccharide compound containing uronic acid derivative. 2. A product according to claim 1 wherein uronic acid is galacturonic acid, glucuronic acid, guluronic acid, mannuronic acid and/or iduronic acid. 3. A product according to claim 1 wherein the derivative is uronic acid lactone, uronic acid ester, uronic acid amide or salt thereof. 4. A heat-treated product according to claim 1 wherein the saccharide compound is a saccharide compound which is selected from pectin, pectic acid, alginic acid, hyaluronic acid, heparin, fucoidan, chondroitin sulfate, chondroitin, dermatan sulfate and/or decomposed product thereof. 5. A product according to any of claims 1-4 wherein the heat-treated product is obtained by heating at 60-350 degree C for several seconds to several days. 6. A heat-treated product according to any of claims 1-5 wherein the heat-treated product is a product obtained by means of a molecular weight fractionation. 7. A food product which is characterized in containing the heat-treated product mentioned in any of claims 1-6. 8. A food product having an anticancer action which is characterized in containing the heat-treated product mentioned in any of claims 1-6. 9. Antibacterial agent which is characterized in containing any of the heat-treated product mentioned in any of claims 1-6. 10. Antiseptic agent which is characterized in containing the antibacterial agent of claim 9. 11. Dentifrice which is characterized in containing the antibacterial agent of claim 9. 12. An apoptosis-inducer which is characterized in containing the heat-treated product of claim 1-6. 13. An anticancer agent which is characterized in containing the heat-treated product of claim 1-6. 14. An inducer for differentiation of cancerous cells which is characterized in containing the heat-treated product of claim 1-6. 15. Antiulcer agent which is characterized in containing the heat-treated product of claim 1-6. 16. A method of inducing an apoptosis which is characterized in using the heat-treated product of claim 1-6 as an effective component. 17. A method for the manufacture of an apoptosis inducing product obtained by heating at a temperature from room to 350 degree C for several seconds to several days under acidic to neutral conditions at least one substance selected from the following (a), (b) and (c): (a) uronic acid or uronic acid derivative; (b) a saccharide compound containing uronic acid or a saccharide compound containing uronic acid derivative; and (c) a substance containing a saccharide compound containing uronic acid or a substance containing a saccharide compound containing uronic acid derivative. 18. A method according to claim 17 wherein uronic acid is galacturonic acid, glucuronic acid, guluronic acid, mannuronic acid and/or iduronic acid. 19. A method according to claim 17 wherein the derivative is uronic acid lactone, uronic acid ester, uronic acid amide or salt thereof. 20. A method according to claim 17 wherein the saccharide compound is a saccharide compound which is selected from pectin, pectic acid, alginic acid, hyaluronic acid, heparin, fucoidan, chondroitin sulfate, chondroitin, dermatan sulfate and/or decomposed product thereof. 21. A method according to any of claims 17-20 wherein the heating is a treatment which is conducted at 60-350 degree C for several seconds to several days. 22. A method according to any of claims 17-21 wherein the heating is a treatment which is conducted under acidic to neutral conditions. 23. A method according to any of claims 17-22 wherein a step of conducting a molecular weight fractionation of the heat-treated product is included.