Guidelines and Precautions. The jury is still out on melatoninâs effects on blood pressure. If you have high or low blood pressure, or take medications to control your blood pressure, it is best to avoid the supplement unless advised otherwise by your doctor.uidelines and Precautions. The jury is still out on melatoninâs effects on blood pressure. If you have high or low blood pressure, or take medications to control your blood pressure, it is best to avoid the supplement unless advised otherwise by your doctor.
1 This can cause the can to bulge or rust.  Use canned tuna by the expiration date on the can. If the can doesn't have a best by date, mark it with the date of purchase and use the tuna within 12 to 24 months of purchase.
Before purchasing canned dog food, check the best if used by or use by date on the container. If this is hard to find or not there, avoid the food as it is likely a low-quality product. Canned dog food should have a shelf life of two to five years from the date of canning. Because canning is a sterilizing process, undamaged canned food can potentially last much longer, but it's best to throw it out if it is past the use by date.