Need proof nutrition is a young science? Read up on Flavonoids.

A few quotes from a paper dated 2013 (link below):

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There has been increasing interest in the research on flavonoids from plant sources because of their versatile health benefits reported in various epidemiological studies. Since flavonoids are directly associated with human dietary ingredients and health, there is need to evaluate structure and function relationship.

Flavonoids ...are known to be synthesized by plants in response to microbial infection.

The number of studies has suggested protective effects of flavonoids against many infectious (bacterial and viral diseases) and degenerative diseases such as cardiovascular diseases, cancers, and other age-related diseases.

Flavonoids are the most common and widely distributed group of plant phenolic compounds, occurring virtually in all plant parts. Flavonoids are an integral part of human and animal diet. Being phytochemicals, flavonoids cannot be synthesized by humans and animals. Thus flavonoids found in animals are of plant origin rather than being biosynthesized in situ.

Flavonoids in food are generally responsible for colour, taste, prevention of fat oxidation, and protection of vitamins and enzymes.

Preparation and processing of food may decrease flavonoid levels depending on the methods used.

Accurate estimation of the average dietary intake of flavonoids is difficult, because of the wide varieties of available flavonoids and the extensive distribution in various plants and also the diverse consumption in humans.

Flavonoids have been consumed by humans since the advent of human life on earth, that is, for about 4 million years. They have extensive biological properties that promote human health and help reduce the risk of diseases.

Flavonoids are also known to influence the quality and stability of foods by acting as flavorants, colorants, and antioxidants.

Intake of antioxidant flavonoids has been inversely related to the risk of incidence of dementia.

Lipid peroxidation is a common consequence of oxidative stress. Flavonoid protect lipids against oxidative damage by various mechanisms.

Antibacterial flavonoids might be having multiple cellular targets, rather than one specific site of action.

The immune system can be modified by diet, pharmacologic agents, environmental pollutants, and naturally occurring food chemicals. Certain members of flavonoids significantly affect the function of the immune system and inflammatory cells.

Dietary factors play an important role in the prevention of cancers. Fruits and vegetables having flavonoids have been reported as cancer chemopreventive agents. The critical relationship of fruit and vegetable intake and cancer prevention has been thoroughly documented. It has been suggested that major public health benefits could be achieved by substantially increasing consumption of these foods.

Naturally occurring flavonoids with antiviral activity have been recognized since the 1940s and many reports on the antiviral activity of various flavonoids are available.

Prevention and cure of diseases using phytochemicals especially flavonoids are well known. Fruits and vegetables are natural sources of flavonoids. Variety of flavonoids found in the nature possesses their own physical, chemical, and physiological properties. Medicinal efficacy of many flavonoids as antibacterial, hepatoprotective, anti-inflammatory, anticancer, and antiviral agents is well established. 

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3891543/

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(Me again) How many flavonoids have been discovered to this point? Many thousands and the number is still growing. Now we can wait for the health benefits of fruits and vegetables to be stuffed into pills, but they still won't be in the balances and substrate formats nature intended us to consume. Why wait? Eat your fruits and vegetables now.

Simple prescription for health:
1) skip breakfast extending your natural daily fasting period.
2) break your daily fast with a large fruit meal. (yum!)
3) have a large vegetable meal for dinner.
4) if you need between meal snacks, eat fruit.
5) never cook your fruit, eat many of your vegetables in salads (not cooked).
5) have a handful of nuts and seeds everyday.

In the "Preparation and processing of food" quote section above, not specifically mentioned in this paper is the destructive effect of cooking on flavonoids - 80% reduction in potency is not uncommon!

The "don't eat fruit" meme is propagated by folks who wish to continue consuming an animal heavy diet because it is culturally familiar, and by those who profit from high fat animal food diets. To their credit, "Paleos" have figured out the least harmful way to consume animal products, but it is not optimal for a variety of reasons. One of them is high fat diets cause insulin resistance, which means very moderate consumption of carbs, effectively eliminating fruit as a significant part of the diet...but fruit is one of the two healthiest food groups on the planet.

High fat low carb diets are not optimal...high carb low fat diets comprised of whole plants in variety is optimal.