My Genes don’t fit
This month’s discussion does not involve me having a hard time buttoning my genes although that can be a problem. What I am referring to the impact our DNA/genes have on relying on a diet containing only vegetable fats (oils) as a food source for key omega 3 fatty acids while excluding animal fats. You dutifully sprinkle flaxseeds on your morning oatmeal and blend chia into your smoothies, doing everything the wellness world tells you to do for those heart-healthy, brain-boosting Omega-3s. But if you are of Irish ancestry flowing as I am, your body might be looking at all those expensive plant oils and shrugging its shoulders. The frustrating truth is that your DNA is perfectly adapted to an ancient maritime environment, making you incredibly inefficient at turning plant-based Omega-3s into the fuel your cells need.
To understand why, we have to look at a biological assembly line inside your body managed by two genes called FADS1 and FADS2. When you eat plant-based Omega-3s—scientifically known as ALA (alpha-linolenic acid)—your body can’t use them right away. They must first be processed by FADS enzymes and converted into EPA and DHA, the long-chain fatty acids that reduce cellular inflammation and protect your brain. Think of plant-based ALA as raw lumber, and EPA/DHA as the finished furniture with the FADS enzymes as carpenters.
Here’s where my Irish heritage crashes the wellness party. Thousands of years ago, my Celtic ancestors weren't relying on seeds and nuts. Their diets were packed with wild-caught fish, shellfish, and grazing livestock. These marine and animal foods are loaded with pre-formed EPA/DHA. Because my ancestors were already eating the ‘finished furniture’, they didn’t need the raw lumber.
Nature is the ultimate optimizer. Because ancient Northern Europeans consumed massive quantities of ready-to-use EPA/DHA directly, their bodies realized that maintaining a robust internal conversion factory was a waste of energy. It was a classic case of evolutionary "use it or lose it." Over generations, the genetic instructions for those FADS enzymes were dialed down. Today, roughly 30 to 40 percent of people with European ancestry carry "low-activity" variants of these specific genes.
Fast forward to the modern era, and the clash between your genetics and your current diet becomes obvious. If you try to get your Omega-3s exclusively from plant sources, you may be relying on a cellular factory that your ancestors permanently downgraded. You could consume double the amount of plant oils as someone whose ancestors hailed from an inland, agrarian society, but only convert a tiny fraction into usable EPA/DHA. The rest gets burned for basic energy, leaving you functionally deficient in the fats your brain craves.
This biological mismatch is exactly why “my genes don’t fit” the standard dietary advice. I can’t out-eat a genetic bottleneck with bigger salads or extra flaxseed oil. You have to honor your ancestry and skip the middleman. By opting for pre-formed EPA/DHA—whether through eating wild salmon, taking a high-quality fish oil, or using marine algae supplements—you bypass that rusty cellular machinery entirely, and give your brain exactly what it’s looking for, in a language your DNA/genes understand.