Caviar is produced using the roe of fish. True caviar is made from sturgeon (including Beluga sturgeon) roe. Other fish such as salmon, paddlefish, lumpfish, trout and cod are also used to make caviar, but such caviar must be labeled indicating the source of the roe (e.g., salmon caviar). To make caviar, the fish eggs are graded, sorted, salted and cured. Caviar is a good source of vitamin D and marine omega-3 polyunsaturated fatty acids, both of which have been associated with lower risk of certain cancers, including breast cancer. Caviar is also a good dietary source of vitamin B12, iron, magnesium, and selenium. However, caviar also contains high levels of sodium and cholesterol, which may contribute to high blood pressure and heart disease.
Cancer-related effects of eating caviar
Frequent consumption of caviar or salted fish roe products has been found to be associated with increased risks of gastric, colorectal and other cancers, presumably because of their high salt content. There are no population studies of which we are aware that specifically address the association between caviar and the risk of breast cancer.
The marine omega-3 fatty acids and vitamin D content of caviar are potentially favorable characteristics for reducing breast cancer risk. However, caviar tends to have a high iron content. While iron deficiency anemia obviously is to be avoided, the contribution of significant heme iron in the diet as a result of regularly consuming caviar could be detrimental for some women. Iron depletion has been shown to lead to significant inhibition of breast cancer cell growth in the laboratory. Relatively high levels of iron in benign breast tissue was found in one prospective study to be associated with an increase in risk of subsequent breast cancer. In addition, excess iron can interfere with the treatment effects of the chemotherapy drugs Adriamycin and cisplatin.
Finally, the high salt, iron and cholesterol levels of caviar and other fish roe products, as well as their association with digestive tract cancers, lead us to suggest that fatty fish such as herring, mackerel or salmon would be a better way to obtain the benefits of marine omega-3 fatty acids and vitamin D.
Scandinavian fish roe spread or creamed caviar (e.g., Kalles Caviar), which is typically sold in tubes, is made from mashed and smoked cod roe, as well as other ingredients such as dill or chives.
It can be difficult to obtain complete nutritional information for caviar purchased online or in specialty stores. There have been reports of unacceptably high levels of preservatives and coloring in some brands of caviar. On the other hand, preservative-free caviar can more easily become contaminated with microorganisms. Caviars from some areas of the world have higher levels of carcinogenic polychlorinated biphenyls (PCBs) and other environmental pollutants than others. Buyers of caviar should be aware of its source and assure themselves of its safety and quality.
Note that while we are continually searching for new evidence specifically concerning this food, there is not much interest in it among breast cancer researchers, so few studies are available.