"Eat more fruits and vegetables."
If I had a dime for every time I heard that recommendation, I'd be a rich man today.
Everyone knows that fruits are healthy... they are the default "health foods."
They come from plants... they're real, whole foods and humans have been eating them for a long time.
Most of them are also very convenient... some people call them "nature's fast food" because they are so easily portable and easy to prepare.
On the surface, they seem like the perfect food.
However... many people have challenged the belief about the health effects of fruit in the past few years.
The main reason is that fruit is relatively high in sugar compared to other whole foods.
This includes table sugar (sucrose) and high fructose corn syrup, which are both about half glucose, half fructose.
The main reason they are harmful, is because of the negative metabolic effects of fructose when consumed in large amounts.
I'm not going to get into the details, but you can read more about the harmful effects of added sugars here.
Many people now believe that because added sugars are bad, the same must apply to fruits, which also contain fructose.
However... this is completely wrong, because fructose is only harmful in large amounts and it is almost impossible to overeat fructose by eating fruit.
Bottom Line:There is a lot of evidence that large amounts of fructose can cause harm when consumed in excess. However, this depends on the dosage and context and does not apply to fruit.
Eating whole fruit, it is almost impossible to consume enough fructose to cause harm.
Fruits are loaded with fiber, water and have significant chewing resistance.
For this reason, most fruits (like apples) take a while to eat and digest, meaning that the fructose hits the liver slowly.
Plus, fruit is incredibly fulfilling. Most people will feel satisfied after one large apple, which contains 23 grams of sugar, 13 of which are fructose (4).
Compare that to a 16oz bottle of Coke... which contains 52 grams of sugar, 30 of which are fructose (5).
A single apple would make you feel quite full, automatically making you eat less of other foods. However, a bottle of soda has remarkably poor effects on satiety and people don't compensate for the sugar in sodas by eating less of other foods (6).
When fructose hits your liver fast and in large amounts (soda and a candy bar) then that can have disastrous consequences... but when it hits your liver slowly and in small amounts (an apple) then your body can easily take care of the fructose.
Also, let's not forget the evolutionary argument... humans and pre-humans have been eating fruit for millions of years. The human body is well adapted to the small amounts of fructose found in nature.
Whereas large amounts of added sugar are harmful to most people, the same can NOT be said for fruit. Period.
Bottom Line: Whole fruits contain a relatively small amount of fructose and they take a while to chew and digest. Humans can easily tolerate the small amounts of fructose found in fruit.
Of course, fruits are more than just watery bags of fructose.There are lots of nutrients in them that are important for health. This includes fiber, vitamins, minerals, as well as a plethora of antioxidants and phytonutrients.
Fiber, especially soluble fiber, has many benefits. This includes reduced cholesterol levels, slowed absorption of carbohydrates and increased satiety. Plus there are many studies showing that soluble fiber can contribute to weight loss ( 7, 8, 9, 10).
Fruits tend to be high in several vitamins and minerals... especially Vitamin C, Potassium and Folate, which many people don't get enough of.
Of course, "fruit" is an entire food group. There are dozens (or hundreds) of different fruits found in nature and the nutrient composition can vary greatly between the different types of fruit.
It makes sense that if you want to maximize the health effects, then focus on the fruit with the greatest amount of fiber, vitamins and minerals compared to the sugar and calorie content.
It is also a good idea to switch things up and eat a variety of fruits, because different fruits contain different nutrients.
Bottom Line: Fruits contain large amounts of important nutrients, including fiber, vitamins, minerals and various antioxidants and phytonutrients.
Multiple observational studies have shown that people who eat more fruits and vegetables have a lower risk of many diseases.
Many of the studies pool together fruits and vegetables, while some look at fruits directly.
One review of 9 studies found that the risk of heart disease reduced by 7% for each daily portion of fruit (11).
A study on 9,665 adults in the U.S. found that fruit and vegetable intake was associated with a 46% lower risk of diabetes in women, but there was no difference in men (12)
One study that looked at fruits and vegetables separately found that vegetables were associated with a reduced risk of breast cancer, but not fruit (13).
There are many other studies showing that fruit and vegetable consumption is associated with a lower risk of heart attacks and stroke, the two most common causes of death in Western countries (14, 15).
One study looked at how different types of fruit affect the risk of type II diabetes. Those who consumed the most grapes, apples and blueberries had the lowest risk, with blueberries having the strongest effect (16).
However, a problem with these types of studies is that they can not separate correlation from causation... that is, that the fruit caused the lower risk of the disease.
Because everyone "knows" that fruits are healthy, people who eat more of them are going to be more health conscious overall and less likely to smoke, more likely to exercise, etc.
That being said, there are also a few randomized controlled trials (real human experiments) showing that increased fruit intake can lower blood pressure, reduce oxidative stress and improve glycemic control in diabetics (17, 18).
Overall, it seems clear from the data that fruits do have significant health benefits.
Bottom Line: There are many studies showing that fruit intake is associated with a lower risk of serious diseases like heart disease, stroke and type II diabetes.
One thing that is often forgotten when discussing the sugar and carb content of fruit... they are also incredibly fulfilling!
Because of the fiber, the water and all the chewing, fruits are very satiating, calorie for calorie.
The satiety index is a measure of how much different foods contribute to satiety.
What this means, is that if you increase your intake of apples or oranges, chances are that you will feel so full that you will automatically eat less of other foods.
In this study, 9 men were placed on a diet that consisted of nothing but fruit (82% of calories) and nuts (18% of calories) for 6 months.
Not surprisingly, the men lost significant amounts of weight. The men who were overweight lost more than those who were at a normal weight.
Overall, given the strong effects fruits can have on satiety, it seems perfectly logical that replacing other foods (especially junk foods) with fruit could help people lose weight over the long term.
Bottom Line: Fruits like apples and oranges are among the most fulfilling foods you can eat. Eating more of them should lead to an automatic reduction in calorie intake.
Even though fruit is healthy for most people, there are some reasons I can think of not to eat them.One obvious reason is some sort of intolerance. For example, eating fruit can cause digestive symptoms in people with fructose intolerance.
The other reason is being on a very low-carb / ketogenic diet. The main goal of these diets is to reduce carbohydrates sufficiently for the brain to start using mostly ketone bodies instead of glucose for fuel.
For this to happen, it is necessary to restrict carbs to under 50 grams per day, sometimes all the way down to 20-30 grams.
Given that just a single piece of fruit can contain more than 20 grams of carbs, it is obvious that fruits are inappropriate for such a diet. Even just one piece of fruit per day could easily knock someone out of ketosis.
Bottom Line:The main reasons to avoid fruit include some sort of intolerance, or being on a very low-carb / ketogenic diet.
Even though whole fruits are very healthy for most people, the same can NOT be said for fruit juices and dried fruit.
Many of the fruit juices on the market aren't even "real" fruit juices. They consist of water, mixed with some sort of concentrate and a whole bunch of added sugar.
But even if you get 100% real fruit juice, it is still a bad idea.
There is actually a lot of sugar in fruit juice, about as much as a sugar-sweetened beverage.
However, there is no fiber and chewing resistance to slow down consumption, making it very easy to consume a large amount of sugar in a short period of time.
Dried fruits (like raisins) can be a problem as well. They are very high in sugar and it is easy to consume large amounts.
Smoothies are somewhere in the middle. If you put the whole fruit in the blender, then it's much better than drinking fruit juice, but not as good as eating whole fruit.
If you can tolerate fruit and you're not on a low-carb/ketogenic diet, then by all means eat fruit... preferably as parts of a healthy, real food based diet that includes animals and plants.
At the end of the day, fruits are "real" foods. They are highly nutritious and so fulfilling that eating them can help you feel more satisfied with less food.
The majority of people would see great health benefits by replacing some of the crap they are eating with fruit.