Healthy Eating: True or false? Find out the real story

Are eggs bad for your heart? How fattening are avocados? Does celery have negative calories? Do grapefruits burn fat? Find out the answers.

eggs in hand 521 (photo credit: Ron Tarver/Philadelphia Inquirer/MCT)
eggs in hand 521
(photo credit: Ron Tarver/Philadelphia Inquirer/MCT)
Healthy Eating: True or False
Are eggs bad for your heart? Are avocados really full of fat? Can too many carrots make you orange? And are negative calories fact or fiction? Find out the truth behind these popular food myths.
True or False: Avocados are the most fattening fruit?
This rumor is technically true. (California) avocados are the highest-calorie fruit in existence – packing just over 300 calories and 29 grams of fat per medium size avocado (200 grams). However, not all fats are created equally – some are actually beneficial for you and the majority of the fat in an avocado falls into this “good” fat category. Only 4 grams are the unhealthy saturated kind; while the rest of the fat content is divided between the heart-healthy monounsaturated fat (66%) and polyunsaturated fat.
Unlike saturated and trans fats, which raise your low-density lipoprotein (LDL) cholesterol, the good fat in avocadoes actually lowers your (bad) LDL cholesterol while raising the good high density-lipoprotein (HDL) cholesterol. Why is that so important? While LDL cholesterol causes plaque to build up on arterial walls, which causes the arteries to narrow, interfering with blood flow, HDL cholesterol helps to remove LDL cholesterol from the blood. In fact, high levels of LDL cholesterol and low levels of HDL cholesterol are associated with increased risk of heart disease and stroke. The goal is to raise the HDL, while lowering the LDL – with an optimal ratio of LDL to HDL of 2 or 3 (definitely less than 4). Substituting harmful saturated fats, such as butter or pastries, with healthy monounsaturated fats, such as an avocado, is an excellent way to start.
Apart from decreasing the risk of heart disease, monounsaturated fats also help to reduce inflammation and to normalize blood sugar levels. Avocadoes are also rich in many essential nutrients including fiber, potassium, Vitamin E and many of the B Vitamins.
True or False: Eggs are bad for your heart?
Many people are afraid to eat more than 1 or 2 eggs a week, why? Because they think that eggs will increase their cholesterol. Now it’s true that eggs are high in dietary cholesterol – more than 200mg, which is more than two-thirds of the American Heart Association's recommended limit of 300 mg a day; however, dietary cholesterol and blood cholesterol are not the same thing. Dietary cholesterol is found in food of animal origin while blood cholesterol is a waxy substance that is produced naturally by the liver. According to the American Heart Association, around only 25% of the cholesterol in our body comes from dietary sources; the rest (75%) is actually manufactured by our liver and other cells.  So does dietary cholesterol increase one’s blood cholesterol levels? While it does increase one’s total and LDL cholesterol, it is not as much as one would think. Other dietary factors specifically saturated and trans fats have a much bigger impact. In fact, studies have shown that over-consumption of both of these “bad” fats can (and does) significantly increases one’s LDL cholesterol, resulting in the buildup of plaque on the arterial walls, which can lead to heart disease. A study (published in the Journal of the American Medical Association) that examined the dietary habits of 117,000 health professionals over a 14-year period found that eating one egg per day is unlikely to increase the risk of coronary heart disease and stroke in healthy adults. So labeling eggs as bad for the heart is essentially connecting the wrong dots. While they may be high in dietary cholesterol, each egg only contains 2 grams of saturated fat as well as no trans fats. What is far worse for your heart is that buttered toast, those chocolate chip pancakes or that cinnamon roll lying next to your eggs.
Now that it has been settled that eggs are not going to be end of your heart, did you know that they are really good for your brain? Apart from being rich protein, eggs are high in choline – a key component of many fat containing structures in the cell membranes. In fact, choline is an important part of two fat-like molecules in the brain (phosphatidylcholine and sphingomyelin) that make up a significant portion of the brain's mass; therefore it is critical for brain function. It is also an integral part of the neurotransmitters which relay messages between the nerves and muscles. Like so many other nutrients, our bodies can only produce tiny amounts of choline, and we must therefore rely on external sources (i.e food) – eggs are one of the highest sources on the planet.
True or False: Some foods have negative calories?
You probably heard this one back when you were in high school – whenever that was - as this is one myth that refuses to fade. Some people say “negative calories” are a joke, while others swear by it. So what is the real story here? Do some foods really decrease your caloric intake?
The theory suggests that the energy used to chew, swallow and basically digest certain fruits and vegetables, such as celery, cucumber and broccoli, exceeds the caloric content of the food. For example, one uses up 80 calories digesting a serving of broccoli that contains only 25 calories; so simple math would dictate that this serving of broccoli has negative 55 calories. While this sounds great, and most of wished it were true, it unfortunately is really not the case. The thermic effect of food - the amount of energy used to consume, digest and then eliminate it - has been (scientifically) established to be far less than supporters of this diet claim. In fact, digestion only uses up about 10% of the food’s total calories on average. So that 80 calorie cup of broccoli still leaves you with 70, and this theory goes out the window.
True or False: Grapefruit burns fat?
Another myth that commonly circulates throughout the high school cafeteria (and girl’s locker room) is that grapefruits burn fat. Contrary to what you may have heard, no food itself can burn fat. However, some foods can help you shed a few pounds – grapefruits are one of them. Before the low carb diet, there was the grapefruit “diet”– a fad regime that strictly limited calories and dictated that dieters drink grapefruit juice or eat a half of a grapefruit with every meal. While the diet isn’t particularly healthy, as it severely limits calories to an extremely low unhealthy level, there is some truth about eating a grapefruit with your meal.  Studies have shown that the enzymes found in grapefruits may help to regulate insulin levels, which typically increase after one eats sugar and other carbohydrates. Metabolic studies have shown that high levels of insulin cause more fat to be stored, while chronically high insulin spikes can eventually lead to insulin resistance, resulting in metabolic syndrome.
Aside from helping out your metabolism, this citrus fruit may also reduce the risk of heart disease as they contain pectin - a form of soluble fiber that has been shown (in studies) to slow down the progression of atherosclerosis (build up of plaque on the arterial walls). Red and pink grapefruits are also abundant in the cancer-fighting anti-oxidant – lycopene; all types of grapefruits (including white) are rich in the immune boosting Vitamin C as well as boost the production and activity of liver detoxification enzymes that are responsible for eliminating toxic compounds from the body – which is also beneficial for weight loss.
True or False: Eating too many carrots can make you orange?
As strange as this one sounds, this rumor is so true. Carrots are rich in beta-carotene, a precursor to Vitamin A. There are two sources of dietary vitamin A: active forms and precursors. Active forms of vitamin A are obtained from animal products such as eggs. These are known as retinoids and include retinal and retinol. The other form is carotenoids – photonutrients responsible for the bright colors of fruits and vegetables. Beta-carotene is one of the 600 members of the carotenoid family, and can be found in abundance in carrots, sweet potatoes and pumpkins - basically any fruit or veggie with a yellow orange color. Once consumed, beta-carotene can be converted into Vitamin A, as needed by the body.
As an anti-oxidant, beta-carotene rids the body of harmful free radicals that can cause aging, cardiovascular diseases and even cancer. It also helps to boost the immune system, helps the reproductive system function properly, is vital for our eyes as it protects them for light-induced damage and of course is a source of vitamin A. However, unlike the active form of vitamin A, which can cause toxic effects if taken in large doses, beta-carotene will only convert itself into the vitamin if needed. It is stored in the liver until then. Nonetheless, overeating beta-carotene rich foods, such as carrots, can result in excess carotene in the blood, resulting in yellowing of the skin most often on the palms and bottom of the feet. This condition is referred to as carotenodermia and is harmless; it can easily be reversed.