Taking multivitamins can be a helpful way to fill in gaps in your diet, but you should always aim to meet your nutritional needs through whole foods. That said, some individuals have specific nutrient requirements and may need to supplement with a multivitamin daily. These individuals typically include women of reproductive age, older adults, and vegans or vegetarians. In addition, those with a compromised gut lining may have difficulty with certain foods that can block absorption of the micronutrients in these types of supplements.
Kirkland is the house brand at Costco and these vitamins are made with ingredients carefully monitored from farm to bottle. They are also Non-GMO Project Verified, USP-Verified, and free of major allergens and artificial colors. This multivitamin is a good choice for those who want a quality product at a reasonable price, especially since you can buy them without a Costco membership.
The problem with this multivitamin is that it takes the same standardized, synthetically produced USP vitamins and minerals (the ones they are telling you to avoid like the plague!) and mixes them into their "food base". Additionally, all of the vitamin and mineral ingredients are delivered at once and have inherent absorption blocking competitions. For example, phytates, lectins, tannins and polyphenols found in this "food" can decrease the body's ability to absorb iron and other important micronutrients. Lastly, using pulverized and dried food in a multivitamin can be problematic for those with sensitive stomachs who can experience unpleasant symptoms such as gas or diarrhea.