In honor of the food issue this week at Synapse, I compiled a list of ten essential diet and nutrition facts you might not know:

1. “Vitamins” are not the same as whole foods. Instant ramen and a multivitamin is not a healthy meal. There is no substitute for a diet of whole foods rich in vegetables, beans, grains and fish.
2. A healthy diet can prevent or even reverse four out of the six leading causes of death in the US. Evidence indicates that diet is more important than genetics in the vast majority of heart disease, stroke, cancer and type 2 diabetes cases.
3. The thinnest, healthiest people in the world eat “high carb” diets. But they definitely do not eat the processed, refined carbohydrates that flood Western culture. If you want to lose weight and live longer without disease, eat more vegetables and whole grains.
4. You get plenty of calcium. Americans consume more calcium than most countries on earth, yet still sport some of the highest rates of osteoporosis. This debilitating disease is more likely caused by insufficient vitamin D, not enough exercise and/or too much protein. Also, excess calcium is linked to prostate cancer and milk to ovarian cancer. Calcium does not support weight loss either.
5. “Fiber” is not the same as vegetables and grains. Fiber supplements do not offer the same benefits as fiber-filled foods, and do not help with weight loss or protect against disease.
6. The best sources of protein are plants and fish. It is relatively easy to get complete protein (i.e., all the essential amino acids) from a diverse diet. Protein from red meat offers more risk than reward. (Yes, pork is red meat.)
7. Fruits and vegetables protect your vision. Both cataracts and macular degeneration are strongly tied to diet.
8. Fats from factories are dangerous. Processed oils and trans fats (not total dietary fat) are associated with heart disease, type 2 diabetes, cancer and obesity. Replacing them with natural oils could save your life.
9. Fats from plants and fish are essential. Mono- and polyunsaturated fats protect against heart disease, type 2 diabetes and memory loss. In moderation they can also aid in weight loss, since they increase the satiety you feel after a meal.
10. You can lose weight on any short-term diet, but you will probably gain back more than you ultimately lose. This is often true even if you stay on the diet. Focusing on long-term health is the best strategy for sustained weight loss, but it requires patience.

What are other common myths about diet and nutrition?

UPDATE: For more information on the health value of oils from fish, please read my answer in the comments section.
http://forms.aweber.com/form/30/split_210533730.htm

Vitamin D

For the past several years the data in support of increasing vitamin D intake for every living human has been mounting. This week the American Journal of Clinical Nutrition features a collection of new research articles addressing the trends in vitamin D status and optimal dose recommendations.

This week’s take home lesson: While current research indicates we should be getting more vitamin D than is presently recommended, as a whole our vitamin D levels appear to have decreased in the past 15 years. The best way to combat this deficiency is with vitamin D supplements.

Vitamin D is a fat-soluble prohormone and essential nutrient produced when ultraviolet radiation (UVB) contacts our skin. It is probably best known for its role in bone metabolism (it has been shown to be more important than calcium for maintaining bone health), however recent studies indicate that vitamin D is essential for other physiological process as well.

Low blood levels of vitamin D have now been associated with many different chronic diseases including cancer, coronary heart disease, multiple sclerosis, Alzheimer’s disease, tuberculosis, depression, hypertension, periodontal disease, schizophrenia, seasonal affective disorder and type 1 diabetes.

In light of these findings, many nutrition researchers have argued for increasing recommended levels of vitamin D intake, but making population-wide recommendations have proved difficult for world health agencies because of large variability and uncertainty in vitamin D requirements.

There are several things to consider when evaluating vitamin D status in an individual. Latitude (sun exposure) is probably the single best predictor of vitamin D status. Anyone living in San Francisco or further north cannot get enough sun exposure to achieve sufficient vitamin D status, particularly during the winter months.

Because vitamin D is fat-soluble, it is retained in body tissues for several months after sun exposure. For this reason, people living at far north latitudes are particularly vulnerable to vitamin D deficiency because they frequently do not store up sufficient vitamin D during the summer to sustain their needs during the winter.

To further complicate matters, it is incredibly difficult to obtain vitamin D through dietary sources. Fatty fish and eggs are the only natural sources of vitamin D, though they are probably insufficient to achieve optimal status. Milk and soy products are typically fortified with vitamin D, as are some juices.

Skin pigmentation, sun avoidance and body composition (high body fat) are all associated with vitamin D deficiency. Darker skin tones do not convert sunlight to vitamin D as easily as lighter skin tones. Sunscreen blocks virtually all vitamin D synthesis. Body fat reduces bioavailability of vitamin D tissue stores.

This week’s study by Anne Looker et al, suggests that increased body mass as well as awareness of skin cancer risk and use of sunscreen have contributed to a significant decline in vitamin D levels in north America in the past decade.

The good news is that supplementation does appear to be effective at improving vitamin D status. Though there is still some disagreement on what the optimum blood levels of vitamin D are, it is generally agreed that they are much higher than currently recommended by any world health organization. One of the principle motivations of the present studies is to inform new vitamin D recommendations.

Kevin Cashman et al offers estimations of dietary requirements of vitamin D for healthy adults. They performed a randomized, placebo-controlled study testing the effects of different vitamin D doses and how they effect blood vitamin D levels.

The absolute minimum amount of vitamin D supplementation recommended by the study is 8.7 ug/day, or approximately 400 IU. This was to maintain blood serum levels greater than 25 nmol/L, and is double the current FDA recommendation for people under age 50. However, this suggestion is only sufficient to avoid deficiencies associated with bone loss and not other chronic diseases.

“The data from the present study clearly show that vitamin D tissue stores, developed during summer via exposure of skin to sunshine, were not sufficient to maintain serum 25(OH)D concentrations of greater than 25 nmol/L in most of the population [during winter], and that dietary vitamin D is an absolute requirement to maintain status above this minimum threshold.”

But the recommendations do not stop here. To maintain blood serum levels of greater than 50 nmol/L–a range more consistent with lowering risk of chronic disease–the study recommends 28 ug/day or 1100 IU of vitamin D. To keep blood serum above 80 nmol/L (from all I have read this is what I would recommend), 41 ug/day or 1650 IU is needed.

Remember this is most important if you are overweight, live north of San Francisco, get little sun exposure or have darker skin. Very rarely do I recommend vitamin supplements (they are not usually effective and are sometimes dangerous), but in this case the evidence is unequivocal.

Vitamin D supplements are easier to find than in the past, but they are usually packaged with calcium and are insufficient in dosage. Men should be wary of excess calcium supplementation since it is associated with an increased risk of prostate cancer.

I will continue looking for a good vitamin D supplement and will post when I find one I am happy with. If you have any recommendations, please share them with us.

Look for supplements where vitamin D is in the form of cholecalciferol, or vitamin D3.