When buying supplements you are trusting a supplier to provide what the label says. the FDA is way too focused on other things to crack down on supplement sellers so brand names become our first line of defense.
Fish Oil: The best bet is to get a prescription for Lovaza or its generic equivalent. prescriptions are much more tightly regulated. If you must buy OTC fish oil, Krill oil is a good bet because Krill live in the cold southern oceans which are relatively pure.
Amazon is a new brand name in supplements. They provide a copy of independent lab analysis of their products. In addition, they are very competitively priced. They are my new go-to source if they make the product I am looking for.
Qunol is the brand of CoQ10 I buy
Sports Research is the brand of K2 + D3 I buy
Pure Encapsulations is recommended by my doctor. Their formula for MTHFR (Homocysteine factors)has a great combo that would take five pills to replicate.
Thorne, Now Foods and Life Extension are all good brands as far as I can tell.
Olive oil quality is something to be as concerned about as supplements. I just finished a book titled Extra Virginity The Sublime and Scandalous World of Olive Oil. This book details the worldwide organized crime network that sells counterfeit Extra Virgin Olive oil (EVOO). Genuine EVOO has major health benefits that include reducing inflammation, reducing bad and increasing good cholesterol. EVOO is the basis for the Mediterranean diet that is best for McDonald genes. EVOO is also darn delicious and it produces satiety. Satiety is the sensation of having enough to eat. EVOO keeps hunger away for hours. If you learn to taste olive oil, you will be able to tell junk from the good stuff. Go to one of these shops that sells nothing but vinegar and oils where they have little cubes of bread for tasting. Taste unflavored EVOO. The good stuff has a distinctive sharp taste that also produces a little catch in the back of the throat. Color is meaningless. great oil can be a rich green or a pale amber.
You should also know that olives are harvested once a year. This means that at some point you will be consuming oil that is at least a year old unless you buy oil from both the northern and southern hemispheres. Keeping oil from deteriorating means keeping it away from heat, oxygen, and light. I have found an importer in Pensacola Florida who buys shipping containers full of oil from Crete. He has it packed either in cans or in the same packing device as box wine. I buy the box wine packaging because it is opaque and as the oil is consumed the bag inside collapses and allows no air to enter. I buy five-liter boxes and I buy three at a time to get a case discount. To my taste this oil is pristine. He ships. Shipping is free on orders over $100. Buy three five-liter boxes and you will get free shipping. The website is below.
https://www.sfpensacola.com/product-category/evoo-vinegar/