Essential fatty acids, particularly in the omega-3 family, exert a multifactorial influence on mood. Omega-3 fatty acids have been shown to have a regulatory influence on serotonin release and degradation. Studies have repeatedly found that omega-3 fatty acid levels are decreased in the serum and cell membranes of a significant proportion of people with depression. Higher intake of omega-3 fatty acids is protective against depression in most epidemiologic studies. Existing trials, though limited, also show they may help treat people with depression. There is concern that desaturation of omega-3 fatty acids from precursors as well as excessive dietary omega-6 intake (which can compete for desaturase enzymes shared with omega-3 fatty acids and further decrease levels of omega-3s) may play a significant role in these deficiencies. Impaired absorption due to gut compromise may also reduce essential fatty acid levels, suggesting once again that bitters may be necessary and helpful.
Botanical sources of essential fatty acids thus may provide a benefit for some people with depression. Omega-6 fatty acids, particularly gamma linolenic acid (GLA), are rich in the seeds of Oenothera biennis (evening primrose) and related species, Borago officinalis (borage), and Ribes nigrum (black currant). Controlled clinical trials have suggested that evening primrose oil might be helpful for relieving depression related to premenstrual syndrome, but not all studies have agreed with these findings. Dr. James Duke points out that evening primrose seeds contain the highest tryptophan content of any herb encountered in his extensive survey of the topic. However, tryptophan is not present in evening primrose oil, and patients would have to eat quite a large quantity of seeds (several grams three or more times per day or more) to obtain sufficient tryptophan to influence mood, a regimen unlikely to be practical or affordable for most patients.
The U.S. diet is already fairly high in omega-6 oils (from sunflower, safflower, and canola oils) and there is some concern that further omega-6 supplementation may only exacerbate omega-3 fatty acid problems. Therefore, Linum usitatissimum (flax), Cucurbitapepo (pumpkin), or Cannabis saliva (hemp) seed oils might be considered as all are sources of the omega-3 fatty acid alpha linolenic acid (ALA). Unfortunately, this will not be effective if the patient’s ability to desaturate them to active omega-3 fatty acids is impaired. Thus, fish oil- or algae-derived docosahexaenoic acid (DHA) might be the best initial supplements if essential fatty acid problems are suspected. These both contain large quantities of preformed, active omega-3 fatty acids.
Essential fatty acids should always be supplemented with antioxidants. This is because they are sensitive to oxidation and need to be protected. There is evidence that people with major depression have deficiencies of some antioxidants, particularly vitamin E. This deficiency offers a separate potential explanation of the essential fatty acid problem: If the fatty acids are being oxidized and damaged, they could be unable to perform their mood-normalizing actions. Chronic inflammation might also promote depression by raising levels of inflammatory cytokines and other chemical mediators that have neurological effects because they deplete zinc, a nutrient essential for desaturation of essential fatty acids to their active forms. Oxidative damage of essential fatty acids, rendering them not only inactive but damaging to neurons, might also be a source of the problem. Botanical antioxidants and anti-inflammatories such as Curcuma longa (turmeric) rhizome, Rosmarinus officinalis (rosemary) leaf, Ginkgo biloba (ginkgo), and quercetin may be good supplements along with traditional vitamin and mineral antioxidants to ensure better utilization of essential fatty acids.