On standard diets most people consume nuts and seeds regularly. But their consumption is even more common among people who follow the ketogenic, vegan, vegetarian or the paleo diet. On the other hand, nuts and seeds are excluded from the Paleolithic-Ketogenic Diet (PKD), the Carnivore diet and the Autoimmune Protocol (Functional Medicine AIP).
Evolutionarily, nuts and seeds have been eaten seasonally, during fall. Thanks to their high energy content, they made it possible for people to store excess body fat for the winter months, when food was scarce. Today, they are available the whole year around, and many of us eat them daily. As there are no more winter months without enough food, there is no time and possibility to get rid of the stored fat gained from nuts, seeds and fruits.
Nuts and seeds are often over-consumed on the ketogenic and the paleo diets, because they replace many traditional cakes, desserts and even bread. There are different processed products, including “flours”, “milk”, “protein”bars, breads and crackers, made with them.
Potential health concerns
As nuts and seeds have high amount of natural plant toxins, such as lectins, oxalates and phytic acid, overeating them might cause serious health risks over time.
Lectins
Different types of lectins have been shown to cause increased intestinal permeability and gut inflammation, that can lead to autoimmune diseases, gastrointestinal disorders and possibly many other chronic diseases. Lectins are also linked to insulin resistance, metabolic syndrome and they can cause red blood cell agglutination, when red blood cells are clumped together and then get destroyed by the body.
Oxalates
Calcium oxalates can cause kidney stones and chronic utinary tract infections. Oxalates have been shown to increase cystogenesis and disease progression in ADPKD (Autosomal dominant polycystic kidney disease).
Calcium oxalate crystal depositions can build up in visceral tissues, blood vessels, bones, cartilage, and skin causing pain and inflammation in the affected area.
Oxalates also irritate the mucosal lining and can cause bloating, pain and other digestive problems.
Phytic acid
Phytic acid reduces bioavailability of minerals, such as zinc, iron, calcium and magnesium because it binds to these minerals in the body and gets eliminated. It can also interfere with protein absorption by making protein unavailable for digestion.
Phytoestrogen
Phytoestrogens can have both estrogenic and anti-estrogenic effects by binding to the estrogen receptors. The health effects and risks are so far controversial. As they act similar way as synthetic estrogen, they can cause obesity, fertility problems and increase the risk of different types of cancer.
Nutrition profile of nuts and seeds
All foods found in nature contain either the combination of protein and fat or protein and carbohydrates. The only exceptions are nuts and seeds. They are the only foods not made by humans that are high in fat and carbohydrates at the same time.They are very addictive, which means that it’s difficult to eat just a small portion at a time. They are high energy density foods and their consumption can easily contribute to weight gain.
Most nuts and seeds are high in polyunsaturated fatty acids (PUFAs), that are easily oxidized and become toxic. In addition, they have an unfavorable omega 3-omega 6 index because they mostly contain omega 6 fatty acids.
Even though the total amount of protein in nuts can be fairly high, their protein profile is suboptimal because one or more essential amino acids are present in small amounts and the protein is not in a bioavailable form. Lysine (Brazil nut, cashew nut, hazelnut, pine nut, and walnut), sulfur amino acids methionine and cysteine (almond), tryptophan (macadamia, pecan), and threonine (peanut) are the limiting amino acid compared to animal products and human needs.
Let’s compare the nutritional value of beef brisket with a few nuts. While brisket is high in protein and fat, all nuts below are fairly high in fat and carbohydrates.
Are there nuts that are safe to eat?
The safest nuts to consume are probably coconut and macadamia nuts. They have lower amount of oxalates, lectins and phytic acid, and a better fatty acid profile - coconut contains mostly saturated, while macadamias monounsaturated fatty acids. But they are also very pour sources of protein and can be extremely addictive and hinder weight loss. They are very high in calories but they have a low satiety index, so it’s easy to overeat them.
In conclusion
Nuts and seeds are part of most people diets. Healthy people can get away with eating many things without problems, but those with chronic diseases need to be much more cautious. Soaking, sprouting and roasting reduce the amount of anti-nutrients in nuts, but most people will never bother making these precautions. And even if they do, nuts and seeds remain high energy foods with an unfavorable fatty acid profile and they can also be very allergenic. I advise all my patients who have any disease, are overweight or obese, to avoid the consumption of all nuts and seeds.
References
https://pages.uoregon.edu/chendon/coffee_literature/2006 J. Agric. Food Chem., Chemical composition of edible nuts.pdf
https://vegfaqs.com/essential-amino-acid-profiles-nuts/#The_Limiting_Amino_Acids_of_Nuts
https://www.mdpi.com/2072-6643/15/2/317#:~:text=However, recent studies have shown,,compounds also produce endocrine actions.