As little as four or five grams of linoleic acid is enough to prevent an omega-6 deficiency. If you are also getting the recommended one to two grams of omega-3 (and most Americans are), that also makes for a nice ratio.
Jennifer writes, "I’ve been using an online food diary to track my daily intake of various vitamins and minerals. The information has definitely motivated me to eat more vegetables! However, my tracker reveals that I am consistently deficient in Omega 6, usually only getting around half of the recommended 12 g per day. I can’t find any information on the consequences of getting too little omega-6. Is deficiency a problem? If so, what's the healthiest way to increase my intake on a mostly vegetarian diet?”
Diet Trackers Are Often Incomplete
First, it’s somewhat likely that your tracker may be underestimating the amount of omega-6 (or linoleic acid) in your diet. Most trackers rely on multiple sources for their nutrition data. They usually start with the USDA’s Food Nutrient Database, which includes extremely detailed nutrient information for thousands of foods. But the USDA database doesn’t include all the latest brands and new products. So, trackers often supplement that with nutrient data provided by manufacturers. They may also allow users to create entries for foods using the information on the Nutrition Facts label.
But manufacturer and user sourced data usually doesn’t include information on omega-6 fats, because these are not required to be listed on the Nutrition Facts label. (User added entries have the additional problem of being riddled with typos, transposed numbers, and misplaced decimal points.)
It’s possible that many of the foods you are adding to your tracker don’t include any data for omega-6 and, as a result, the tracker is underestimating your intake. (Dietary surveys suggest that typical intake for American women is 12-13 per day.) Sometimes trackers will use an asterisk or other symbol to indicate that the data for that nutrient is incomplete.
How Much Omega-6 Do You Need?
But, just for the sake of argument, let’s say that you really are only taking in six grams of omega-6 fats per day. Are you at risk of an essential fatty acid deficiency? Not at all.
It’s important to realize that the Institute of Medicine’s recommendation for linoleic acid is not a Recommended Dietary Allowance (RDA) but an Adequate Intake (AI). An RDA reflects the average daily intake level that will be enough to meet the nutrient requirements of most healthy individuals. When the agency feels that there isn’t enough evidence to establish an RDA, they set an AI, which reflects the amount that’s typically consumed by healthy people.
Other worldwide health organizations have been a little braver, setting actual recommended intakes for Linoleic Acid. But these are all over the map, ranging from 2% to 9% of calories. (The US guideline works out to about 6% of calories). But, again, these recommendations are not necessarily meant to indicate the amount required to prevent deficiency. They are also taking into account things like preventing heart disease, how much total fat should be in your diet, and what kind of fat you might be eating if you weren’t eating omega-6.
The International Society for the Study of Fatty Acids and Lipids (ISSFAL) suggests that 2% of calories (or around four grams per day) is all it takes to prevent nutrient deficiency. They even suggest that it might be a good idea to establish an upper limit for omega-6 intake, which makes sense. After all, we’ve been hearing a lot about how consuming more PUFAs (a category which includes both omega-6 and omega-3) is good for your heart.