Go Nuts!

One of our weekly reads is Dr. Mirkin's e-Zine.  The following information is taken from his November 22, 2015 issue.

Good Fat in Nuts

A review of 61 studies shows that feeding people one ounce of tree nuts per day for three to 26 weeks helped to lower total cholesterol, the harmful LDL cholesterol, triglycerides, and Apo B, the main fat-protein in VLDL and LDL (American Journal of Clinical Nutrition, Nov 11, 2015). Tree nuts include walnuts, pistachios, macadamia nuts, pecans, cashews, almonds, hazelnuts and Brazil nuts. Doubling the amount of nuts to two ounces per day lowered cholesterol and triglycerides even more. NOTE: These studies were done on nuts from trees, but it appears that peanuts confer the same benefits.

How Nuts Lower Cholesterol and Triglycerides
Nuts lower cholesterol and triglycerides because they are good sources of soluble fiber which cannot be absorbed in your upper intestinal tract. The soluble fiber passes unabsorbed to your colon where bacteria ferment it to form short-chain fatty acids that are absorbed from your colon into your bloodstream. Short-chain fatty acids lower cholesterol by traveling to your liver where they prevent your liver from making cholesterol. Nuts lower triglycerides because soluble fiber is a gel that sticks to other components in foods that you eat to reduce the absorption of calories in your upper intestinal tract. All extra calories can be converted by your liver to triglycerides, so reducing calories lowers triglycerides.

Why Nuts Don’t Cause Weight Gain
Nuts are a rich source of fat, but the fat in nuts is absorbed very poorly (Am J Clin Nutr, Jan, 2015;101(1):25-33). For example, the fat in almonds is located inside the cells of the almond kernel. Even after prolonged chewing, most of the almond cells remained intact and the fat is still inside the cells. Humans lack the enzymes to break down these cell walls. You have to liberate fat from inside cells to absorb it into your body. Furthermore, the fats in nuts are coated with proteins called oleosins that help to prevent fat from being absorbed. Since fat is absorbed only after it is released from cells, most of the fat in almonds cannot be absorbed in the upper part of your intestinal tract. Some of the fat that has passed through the upper intestines is absorbed after the nuts reach the colon, where bacteria ferment the cell walls to release some of the fat (Am J Clin Nutr, Sept 2004;80(3):604-13). Cooking helps to break down the cellulose that makes up cell walls, and it also breaks down the oleosins which coat fat, to allow the fat to be absorbed at a higher rate (American Journal of Physical Anthropology, January 2015;56(1):11–18). Grinding to make nut butters and milks also breaks down cell walls to increase available calories.

The calorie count of nuts is really lower than what you read on the label. The calorie counts shown on food labels are computed from how much heat can be produced by the food in a laboratory. However, this method of measuring calories is meaningless for foods that are poorly absorbed. The number of calories listed on the label can be much higher than those a person actually absorbs; many of the potential calories pass through, undigested, in the person’s stool. This explains why blood fat levels are lower than expected after a person eats nuts. More at Why Nuts Won’t Make You Fat

Nuts are Healthful
Epidemiological studies on populations show that eating nuts is associated with reduced risk for heart attacks, gallstones, diabetes and some cancers. Many studies show that eating nuts lowers high blood pressure, cholesterol and belly fat, and that nuts are not associated with gaining weight (Nutrients, July, 2010;2(7):652-82). A new study confirms that eating almonds reduces belly fat, the type of fat that is associated with diabetes and heart attacks (Journal of the American Heart Association, January 11, 2015). This result is likely to apply to other tree nuts as well.