In my preceding post, I was discussing the nature of global agriculture and what we can buy in our local supermarkets. For those of us living a plant-based lifestyle, this is resulting in the lack of diversity in our diets. This is not to say that a plant-based diet is not diverse, but that our options for diversity are limited by the commercial nature of agriculture. What are unclear are the health implications of eating from a commercially driven menu. This is a theme I would like to explore here.
As a summation of world agriculture, this is dominated by very few crops. Cereals account for more than two thirds of the cropland of the World. The FAO (Food and Agriculture Organisation of the United Nations) estimates there are as many as 250-300,000 edible plant species and their estimates are that between 150-200 plant species are used in any frequency.
Further, the FAO observes:
Since the 1900s, some 75 percent of plant genetic diversity has been lost as farmers worldwide have left their multiple local varieties and landraces for genetically uniform, high-yielding varieties. More than 90 percent of crop varieties have disappeared from farmers’ fields.
The full discussion on the environmental and agrobiodiversity implications is discussed in my last post.
Impact of Food Trends
The perception of the marketplace is that there is a lot more choice than there once was; there are new superfoods and superfruits appearing on shelves every day. However, the reality is that this is just another commercial fashion-system, rather than representing a cumulative expansion of the options in a supermarket. Just because paisley or tartan patterns are popular one year, does not mean they stay in stores the following year. Likewise an ingredient becomes a dietary fad, does not make it a staple on the selves. Often these new ‘finds’ are a marketing distraction from the stock standard produce that is always available. Other times we rediscover ingredients, through marketing, such as the popular weight loss Garcinia Cambogia, is really the 1990’s diet supplement Brindleberry, and likewise the Goji Berry are the 1990’s Wolfberry.
With wealthy western cultures creating the new demands for specific crops, there is often an impact of food trends creating an unbalance in the marketplace of crop production.
Recent agricultural waves have been made for the popularity of coconut, the Chia boom: ‘With 239% growth, chia category set to hit $1 bn by 2020’; and Quinoa , Kale amongst others also being fashionable.
Often these crops supplant others in the global market, displacing local produce and changing the environment in ways that are only now becoming apparent.
Is eating seasonally important?
Anyone who has ever had a fish tank, a garden or a worm farm can start to see the parallels between these microbiomes and our own stomachs. These are all balanced environments that need the correct mix of factors to be in healthy balance. In an earlier blog on our gut microbiomes, it is becoming increasingly clear that the status of our gut health is vital to both our mental and physical health.
I’ve often pondered if our relatively recent change from a diet that is based on seasonality (and location) to one where all ingredients are available perennially if this is a positive one. If there is a clear benefit to rotating crops for soil health, does this analogy extend to our own gut health?
There are some views that eating the same foods in repetition is what is driving the higher frequencies of food allergies and intolerances. There is recent evidence that rotating foods will reduce the chances of complications amongst those who are prone to allergies. This lack of diversity has also been linked to the increase of other diseases.
“It has been suggested that the availability of foods all year round has contributed to the increase in food allergies and intolerances, higher levels of obesity and modern chronic diseases such as type-2 diabetes.”
Are cold fruit and vegetables better?
In a modern life what we eat is at the mercy of our supermarkets, our distance from a farmer’s market, or how green a thumb we have. Supermarkets which are driven by the logistical need to centralise large quantities of food that deliver on the commercial objectives of their share-holders are part of the problem here, e.g. there are many examples of this, an Australian supermarket was claiming to sell ‘fresh bread’ daily, but the bread was actually found to be par-baked in Ireland. Probably one of the more carbon-negative mouthfuls you could take.
For anyone eating a lot of fruit or vegetables, the drop in quality over the last decade has been more pronounced as more produce is ‘chilled’ for longer. The result is food that is less healthy than frozen food.
Frozen vegetables can be more nutritious than supposedly fresh supermarket produce, a study has found [note: this research was for a frozen food brand].
Fresh vegetables can lose up to 45 per cent of important nutrients by the time they reach the dinner table.
Time spent in storage, in transportation and sitting on the shelves means it can be more than two weeks from the vegetables being picked to being eaten.
Goodness draining away: Green beans lose 45 per cent of nutrients in the 11 to 15 days it takes to reach the dinner table, while broccoli typically has a 25 per cent nutrient loss
The reality being that it takes more than two weeks for most produce to hit the supermarket shelves. There are also some unqualified shipping techniques that are used to ‘preserve’ the freshness of these products. Fruit is often exposed to 1-methylcyclopropene (1-MCP) to preserve the shelf life and sprayed with fungicides before it actually hits the shelf.
Benefits of seasonal produce
The opportunity-cost for the convenience of all this cornucopia of ‘preservation’ is the financial cost of eating fresh. It costs more to eat fresh. With this in mind, what is the case for eating seasonally?
There is the environmental benefit of not contributing to a larger than necessary carbon-footprint by consuming unprovinced produce. Although, while we are acculturated to think that local is better – supermarkets do generally buy according to industry codes and standards. We like to think that all local produces are using ‘organic’ and pre-modern farming techniques – but who is accrediting their behaviour? From experience, asking questions is always better than buying into the fun of a farmers market.
In an interview with the Korea Herald, Kim Eun-kyung, president of the Korea Vegetable Sommelier Association, summarises some of the benefits of eating seasonally:
“To me, superfoods are local foods grown in season. They taste better, are cheaper and rich in nutrition,”
The 49-year-old fruit and veggie guru said that fruit and vegetables eaten in season have a higher phytochemical content and contain more nutrients. If consumers buy produce which is not in season, it is likely to have been grown in artificial conditions, or picked prematurely and transported long distances. All these factors not only affect the taste, but also the nutritional content.
The interesting observation here is that seasonality is linked to nutritional content. This appears to be a scientific truth as well. In discussing Vitamin C within horticultural crops, Lee, et al (2000) state:
Vitamin C, including ascorbic acid and dehydroascorbic acid, is one of the most important nutritional quality factors in many horticultural crops and has many biological activities in the human body.
The content of vitamin C in fruits and vegetables can be influenced by various factors such as genotypic differences, preharvest climatic conditions and cultural practices, maturity and harvesting methods, and postharvest handling procedures.
The higher the intensity of light during the growing season, the greater is vitamin C content in plant tissues.
Looking at a different crop, a study on the nutritional content of Spinach has been directly linked to being grown seasonally:
Over-winter spinach, which was planted in late fall and harvested in the spring, had much higher levels of total phenolics and antioxidant capacity than spinach planted in early fall and harvested in late fall, indicating that growing conditions, as well as biotic and abiotic stresses, influenced phenolic metabolism.
It’s not unreasonably to extrapolate out nutritional benefits for all types of plants when they are grown in accordance to how they have evolved.
With the advent of electricity, the digital watch and 24/7/365 shopping, the role of the seasons is the most removed from human life as it ever has been. The majority of human society and culture has been dominated by either the feminine seasonality of the moon or the masculine movement of the sun.
While culture has evolved, we are not too different from our primordial ancestors in biology. Research into the gut microbiome is revealing that we are only just starting to understand the role of our guts on our mental and physical health. In this context, Michael Berk, a professor of psychiatry and medicine, believes that traditional diets are healthier because they are ‘whole, unprocessed and nutrient-dense foods’ compared to modern diets.
The other characteristic for consideration here is that most traditional diets, like that of the Mediterranean etc are all diets that are based around the seasonal rotation of similar foods. This is in stark contrast to the modern supermarket that provides a limited variety of foods every day of the year. Leaves us with questioning the role of the seasonality of foods and the relationship with our microbiome health. Getting to the root of the issue, is the vegan diet diverse enough, if we leave it in the hands of supermarkets.