Dr. Mary (Clifton) Wendt,
What is the appropriate amount and type of fat individuals should get in
their diet? What is the position of foods of high-fat foods like avocados,
nuts and oils in a health diet? Good science supports that reducing meat and
dairy consumption decreases heart disease (1), but other studies suggest
that substantial decreases in dietary fats may contribute to neurologic
disease (2). Some nutrition experts recommend severe restriction of dietary
fats for optimal health, including the avoidance of meat, dairy, eggs, but
also avocado, nuts and vegetable oils.
However, recent studies show benefit to nut consumption. Consumption of a handful of nuts daily decreases the risk of certain cancers (3) and reduces risk of cardiac death due to cardiovascular disease (4). Studies conclude that nuts play an important role in a healthy diet in order to minimize heart disease risk and get multiple health benefits. What could possibly be in nuts that so powerfully protects us from disease? Nuts are at least partially beneficial to individuals because they represent such a good source of healthy fatty acids.
Apart from being a source of energy, fatty acids have a wide range of physiologic functions. Many fatty acids can be produced endogenously; however, n−3 and n−6 polyunsaturated fatty acids are essential fatty acids that must be provided in the diet. The long-chain metabolites of these essential fatty acids are needed for healthy heart and cellular function. Long chain essential fatty acids also influence gene regulation, helping the body go back to the proper spot on our DNA to collect the information it is looking for. EPA and DHA are of particular interest. Although their action is not fully understood, they most likely protect against heart disease and promote healthy neurologic function.
The major dietary source of EPA and DHA is seafood, but they can also be found in lean red meat, in organ meats such as liver and brain, and in eggs; very small amounts are found in dairy products. Consequently, vegetarians, who do not eat meat or fish, and vegans, who in addition exclude eggs and dairy products from their diets, have very low or negligible intakes of EPA and DHA. However, vegetarians eat much higher amounts of linoleic acid (18:2n–6; LA), which is largely derived from plant sources. EPA and DHA can be synthesized in the body from alpha-linolenic acid (18:3n-3; ALA). It's argued that the process of making your own EPA and DHA is limited in humans, but even at a limited rate, people who get most of their calories from plants can still make plenty of EPA and DHA on their own. That's because of the much higher content of alpha-linoleic acid in a vegetarian diet makes that building block more readily available.
Last summer, I talked with Brenda Davis and Michael Greger about this concern, for quite some time, as we made our way back from morning boot camp at Vegetarian Summerfest. Because people who limit meat and dairy in their diet have less fat in their diet, it makes sense the they will have less fat to measure floating around in their blood. Brenda thinks that the healthier fats measure lower in the blood of healthy eaters because so much of the healthy fats are tied up for immediate use in making healthy cell membranes and healthy levels of sex hormones. Dr. Greger concurred that if healthy eaters supplemented their diets with nuts, they would enjoy a health benefit from that addition.
Tess and I have talked about the position of nuts and oils in Get Waisted meal plans and diet recommendations many times. While I do agree that dietary restriction of nuts and oils is important for limiting calories and cutting excess fat, I do not think that dietary exclusion of these foods will result in superior health outcomes. For this reason, we recommend no more than a small handful of nuts (approximately 14-20 kernels) and 1 teaspoon of oil per day. We prefer the consumption of nuts over oil as a source of concentrated healthy fat. Even with the recommendation for healthy levels of fats, my dietary fat recommendations are about half the recommended fat content of a Standard American Diet (6) and half the fat recommended by the American Heart Association (7). This is a level of healthy dietary fat that will lead to excellent health.
We began this archive as a means of assisting our visitors in answering many of their health and diet questions, and in encouraging them to take a pro-active part in their own health. We believe the articles and information contained herein are true, but are not presenting them as advice. We, personally, have found that a whole food vegan diet has helped our own health, and simply wish to share with others the things we have found. Each of us must make our own decisions, for it's our own body. If you have a health problem, see your own physician.